Morphology and SSR markers-based genetic diversity analysis of sesame varieties released in China

doi:10.21203/rs.3.rs-3091046/v1

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Morphology and SSR markers-based genetic diversity analysis of sesame varieties released in China

https://doi.org/10.21203/rs.3.rs-3091046/v1

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Background Sesame, one of the most important oil crops in the world, is rich in sesamol, sesamin, and other antioxidant substances, and can be consumed as oil, food, and vegetable. It has a high nutritional and economic value. To reveal the genetic diversity of the sesame varieties at the molecular and morphological levels, 25 pairs of simple sequence repeat (SSR) primers and 56 biological traits were applied to 101 Chinese sesame varieties released in recent decades, as well as 62 Chinese landraces and 20 alien accessions.

Results The results indicated that a total of 166 SSR bands were detected, with an average of 6.64 per marker; the total alleles were 40.35, with an average of 1.614 per primer pair. Among them, the marker LG141 detected a maximum of 1.85 alleles, and SB393 had a minimum of 1.23 alleles. Shannon’s information index ranged from 0.2732 to 0.6497 with an average value of 0.5292; the polymorphic information index ranged from 0.0859 to 0.6357, with an average value of 0.5254, and the average heterozygosity (He) was 0.3246, suggesting that these sesame accessions have a narrow genetic diversity. The results of the unweighted pair-group method with arithmetic averaging (UPGMA) clustering were consistent with those of the binary principal component analysis, and the 183 sesame lines were categorized into three UPGMA groups. The genetic diversity coefficient of sesame germplasm is generally small, and the genetic relativeness is close. The genetic diversity coefficient of Chinese accessions is not much different from that of foreign resources. Moreover, a DNA fingerprint database of 183 sesame accessions including varieties and germplasm resources was constructed, and a corresponding two-dimensional code was developed.

Conclusion The results of this study provide data reference for the breeding and promotion of new sesame varieties in China, the protection of new variety rights, the inquiry and identification of DNA genetic information of varieties, and the development and utilization of germplasm resources domestically and abroad.

Sesame

SSR marker

Genetic diversity

Fingerprinting

Sesame, also known as liposomes and flax, is an annual herbaceous plant that belongs to the flax family [1, 2]. Sesame is widely cultivated in tropical and subtropical regions from approximately 40°N latitude to 40°S latitude. It is grown in more than 50 countries in the world [3]. The seeds are rich in fat, protein, vitamin E, and other nutrients, as well as sesamol, sesamin, and other antioxidant substances [3, 4]. It is a good antiaging and health product and one of China’s major oil crops [5]. All parts of the sesame plant have a wide range of uses. The oil extracted from sesame seeds has an aromatic smell [6] and can be used as cooking oil and also for medicinal purposes [7, 8]. Pastries made from sesame are traditional snacks and are popular among people [9]. Sesame leaves are rich in vitamins, calcium, magnesium, selenium, and other trace elements. In the Henan province and its neighboring regions of China, people have the habit of consuming sesame leaves. Thus, sesame leaves can be used as vegetables [7]. Sesame leaf is also rich in flavonoids, which have stable composition and are not easy to degrade, making it a good cosmetic additive. Sesame flowers have a bright color and can attract bees to make honey, preventing chilblains and hypoglycemia [10]. Flower tea made from sesame buds has gradually become a healthy food and is highly attractive to young people. A growth/culture medium made from sesame stalks is a good substance for growing mushrooms, and the mature stem has a ripening effect on persimmon. In recent years, some advances have been made in sesame production, processing, trade, and policy support in China. However, the research on machinery for sesame harvesting, and the breeding of new varieties suitable for mechanized harvesting is still lagging, thereby increasing the cost of sesame production and reducing production efficiency, which is greatly affecting the development of the domestic sesame industry. With the increasing demand for edible oil in China, the discrepancy between the supply and demand of domestic edible vegetable oil has become increasingly high. Various measures have been taken to continuously increase the yield per unit and the total yield of sesame, and improving the production efficiency of sesame has gradually become a major target in the sesame community.

Morphological traits, such as growth habit, plant height, plant type, leaf shape, leaf arrangement, flower color, stem color at maturity, capsule color at maturity, hairiness of the stem, number of flowers per leaf axil, number of capsules per leaf axil, number of carpels per capsule, seeds per capsule, days to flower, days to maturity, seed coat color, seed yield, and other agronomical traits, were considered the most representative agro-morphological traits used to estimate the genetic diversity of sesame [11]. However, these agronomical traits are prone to being affected by the environment. The other methods for variety identification using physiological and biochemical measurements are also affected by the environment, making the accuracy and authenticity of identification inefficient. With the development of molecular biology techniques, molecular markers have become powerful tools for identifying the purity and authenticity of varieties because of their outstanding advantages, such as high reliability, rich information, rapid detection, and convenient operation. Uzun et al. [9] employed the Bulked segregant analysis strategy to map the closed capsule trait in an F₂ population derived from crossing the closed-capsular mutant “cc3” with the Turkish variety “Muganli-57”; a total of 72 closed-capsular linked primers were screened and a tightly linked AFLP tag was identified. More recently, Phumichai et al. [12] constructed an F₂ population, and 192 AFLP primers were screened, of which 9 polymorphic AFLP bands were identified. One AFLP molecular marker, Si-SR-32-19, can differentiate between the genotype of a capsule and a closed capsule. In our laboratory, Wu et al. [13] constructed a high-density genetic map in a sesame population containing 224 recombinant inbred lines, 1 QTL for capsule number per plant, and 5 QTLS related to capsule length were identified using multiple interval mapping and mixed linear complex interval mapping, respectively. Wei et al. [14] used genome-wide association analysis to locate an SNP site that was closely linked to the number of axillary capsules per leaf and found that it was a dominantly inherited trait.

In this study, DNA fingerprinting of Chinese sesame varieties, landraces, and alien lines was performed using gene-based SSR markers. The genetic diversity was further evaluated by combining the SSR markers and agronomical traits, aiming to provide insight into the genetic structure affected by the breeding selection of sesame in the past decades and valuable molecular markers for the authentic identification and protection of sesame varieties.

Morphological and agronomical diversity of the sesame accessions

To assess the phenotypic diversity of the 183 sesame cultivars (Table 1), we investigated 56 qualitative and quantitative morphological and agronomical characteristics related to growth, branching, leaf, stem, nectary, flower, capsule, and seed traits as well as the time of the beginning of flowering, time of final flowering, seed maturity time, growth period, drought resistance, tolerance to waterlogging, and disease resistance (Supplementary Table S1). The sesame cultivars showed extensive diversity in the morphological traits with the most prominent ones being corolla length, leaf blade length, carpopodium length, leaf blade length/width ratio, plant height, capsules per plant, seed protein content, seeds per capsule, number of nodes to first flower, void axis length, first capsule height, growth period, time of the beginning of flowering, time of final flowering, internode length, petiole length, leaf blade width, capsule length, yield per hectare, seed oil content, and 1,000-seed weight (Fig. 1).

Table 1

Variety name and origin of sesame accessions used in the present study
Code	Variety	Origin
TP00	Zhongzhi No.1	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP01	Zhongzhi No.2	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP02	Zhongzhi No.3	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP03	Yiyangbai	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP04	Zhongzhi No.5	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP05	Zhongzhi No.7	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP06	Zhongzhi No.8	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP07	Zhongzhi No.10	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP08	Zhongzhi No.11	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP09	Zhongzhi No.12	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP10	Zhongzhi No.13	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP11	Zhongzhi No.14	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP12	Zhongzhi No.15	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP13	Wulonghei	Local resources in Jiangxi province
TP14	Wan9013-4	Nanyang Academy of Agricultural Science
TP15	Zhongzhi No.16	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP16	Zhongzhi No.17	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP17	Zhongzhi No.18	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP18	Zhongzhi No.21	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP19	Zhongzhi No.22	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP20	Zhongzhi No.23	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP21	Xiangzhi No.2	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP22	Ezhi No.1	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP23	Ezhi No.2	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP24	Ezhi No.3	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP25	Ezhi No.4	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP26	Ezhi No.5	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP27	Ezhi No.6	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP28	Ezhi No.7	Xiangyang Academy of Agricultural Science, Hubei Province, China
TP29	Xiezhi No.1	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP30	Hangzhi No.2	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP31	Xiongzhi No.1	Xiongkou Commune Agricultural Science Experimental Station of Qianjiang County, China
TP32	Xin No.5	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP33	Wanzhi No.1	AnHui Academy of Agricultural Sciences, China
TP34	Wanzhi No.2	AnHui Academy of Agricultural Sciences, China
TP35	Wanzhi No.3	AnHui Academy of Agricultural Sciences, China
TP36	Ganzhi No.1	Jiangxi Academy of Agricultural Sciences, China
TP37	Ganzhi No.3	Jiangxi Academy of Agricultural Sciences, China
TP38	Ganzhi No.4	Shangrao County Agricultural Science Institute of Jiangxi province, China
TP39	Yuzhi No.4	Zhumadian Academy of Agricultural Sciences, China
TP40	Yuzhi No.7	Zhumadian Academy of Agricultural Sciences, China
TP41	Yuzhi No.10	Zhumadian Academy of Agricultural Sciences, China
TP42	Zhuzhi No.2	Zhumadian Academy of Agricultural Sciences, China
TP43	Zhuzhi No.3	Zhumadian Academy of Agricultural Sciences, China
TP44	Zhuzhi No.4	Zhumadian Academy of Agricultural Sciences, China
TP45	Zhuzhi No.11	Zhumadian Academy of Agricultural Sciences, China
TP46	Zhuzhi No.14	Zhumadian Academy of Agricultural Sciences, China
TP47	Zhuzhi No.15	Zhumadian Academy of Agricultural Sciences, China
TP48	Zhuzhi No.16	Zhumadian Academy of Agricultural Sciences, China
TP49	Zhuzhi No.18	Zhumadian Academy of Agricultural Sciences, China
TP50	Zhuzhi No.19	Zhumadian Academy of Agricultural Sciences, China
TP51	Shangzhi 429	Persistent Sesame Research Institute of Shangcai County, Henan Province, China
TP52	Yuzhi 18	Pingyu County Agricultural Science Station, Henan Province, China
TP53	Luo 12	Luohe Academy of Agricultural Sciences, Henan Province, China
TP54	Luozhi No.15	Luohe Academy of Agricultural Sciences, Henan Province, China
TP55	Zheng98N09	Henan Academy of Agricultural Sciences, Henan Province, China
TP56	Luoyouzhi G2-1	Luohe Academy of Agricultural Sciences, Henan Province, China
TP57	Jizhi No.1	Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, China
TP58	Jizhi No.3	Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, China
TP59	Jihangzhi No.1	Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, China
TP60	Ningzhi No.1	Nanjing Institute of Agricultural Sciences in Jiangsu Hilly Area, ,China
TP61	Shan’zhi No.3	Institute of Industrial Crops Northwest Sci-Tech University of Agriculture and Forestry, China
TP62	Fenzhi No.7	Shanxi Academy of Agricultural Sciences,China
TP63	Zhongfengzhi No.1	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP64	Zhongzhi No.30	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP65	08A11	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP66	08D17	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP67	Zhu 92701	Zhumadian Academy of Agricultural Sciences, China
TP68	Zhu 86–207	Zhumadian Academy of Agricultural Sciences, China
TP69	Yuzhi 07610	Pingyu County Agricultural Science Station
TP70	Xiniujiao	Local resources from Gucheng County, Hubei province, China
TP71	Zhushanbai	Local resources from Zhushan County, Hubei province, China
TP72	Hongmaoqiu	Local resources from ZhongXiang County, Hubei province, China
TP73	Jiugentou	Local resources from Wuchang County, Hubei province, China
TP74	Bagucha	Local resources from Mianyang County, Hubei province, China
TP75	Dawuzhima	Local resources from Dawu County, Hubei province, China
TP76	Miaoqianzhima	Local resources from Qingyang County, Anhui province, China
TP77	Fozuo	Local resources from Ji’an County, Jiangxi province, China
TP78	Jiangxifengchengbaizhima	Local resources from Fengcheng County, Jiangxi province, China
TP79	Lushibaizhima	Local resources from Lushi County, Henan province, China
TP80	Jiangkoubai	Local resources from Shixing County, Guangdong province, China
TP81	Laibinbaizhima	Local resources from Laibin City, Guangxi province, China
TP82	Wangmobaizhima	Local resources from Wangmo County, Guizhou province, China
TP83	Fufengzhima	Local resources from Fufeng County, Shanxi province, China
TP84	Aizibai	Local resources from Wuxi County, Hubei province, China
TP85	Kaixianbaizhima	Local resources from Kai County, Sichuan province, China
TP86	Yunnanhonghebaizhima	Local resources from Honghe County, Yunnan province, China
TP87	Songyangliulengzhima	Local resources from Songyang County, Zhejiang province, China
TP88	Shanghailiujiaobaizhima	Local resources from Chuansha town, Shanghai City, China
TP89	Beijingbawangbian	Local resources from the suburban areas of Beijing, China
TP90	India C-50	Variety introduced from India
TP91	India SVPR1	Variety introduced from India
TP92	Soviet tashigan 122	Variety introduced by the former Soviet Union
TP93	Cuba-3	Variety introduced from Cuba
TP94	Mozambique Oro 9/71	Varieties introduced from Mozambique
TP95	Zhongzhi No.9	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP96	Xiangheizhi2078	Xiangyang polytechnical college, Hubei Province, China
TP97	Lezhi08	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP98	Ganzhi No.2	Shangrao County Agricultural Science Institute of Jiangxi province, China
TP99	Ganzhi No.5	Agricultural Bureau of Jiangxi County, China
TP100	Ganzhi No.6	Jiangxi Academy of Agricultural Sciences, China
TP101	Ganzhi No.7	Jiangxi Institute of Red Soil, China
TP102	Ganzhi No.8	Jiangxi Institute of Red Soil, China
TP103	Ganzhi No.9	Jiangxi Academy of Agricultural Sciences, China
TP104	Zhuzhi No.10	Zhumadian Academy of Agricultural Sciences, China
TP105	Ji 9014	Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, China
TP106	Jiheizhi No.1	Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, China
TP107	Tanma	Local resources from Anlu County, Hubei province, China
TP108	Wuninghei	Local resources from Wuning County, Jiangxi province, China
TP109	Qingma	Local resources from Jinxian County, Jiangxi province, China
TP110	Aijiaojinhunagma	Local resources from Jinxian County, Jiangxi province, China
TP111	Jingchaima	Local resources from Jinxian County, Jiangxi province, China
TP112	Jiangxijinxian NA1	Local resources from Jinxian County, Jiangxi province, China
TP113	Xinheheizhima	Local resources from Congzuo City, Guangxi province, China
TP114	Heizhima	Local resources from Laibin County, Guangxi province, China
TP115	Xiadianheizhima	Local resources from Congzuo City, Guangxi province, China
TP116	Guangxi N.A1	Local resources from Guangxi province, China
TP117	Guangxi N.A2	Local resources from Guangxi province, China
TP118	Vietnam NA1	Varieties introduced from Vietnam
TP119	Vietnam NA2	Varieties introduced from Vietnam
TP120	Myanmar N.77.7	Varieties introduced from Myanmar
TP121	Jiguang No.2	Haikou Sesame Breeding Assistance Group, China
TP122	Zhuxizhima	Local resources from Zhuxi County, Hubei province, China
TP123	Fazhima	Local resources from Tianmen City, Hubei province, China
TP124	Linxianzhima	Local resources from Lin County, Henan province, China
TP125	Jinzhaizhima	Local resources from Jinzhai County, Anhui province, China
TP126	Feixiyouzhima	Local resources from Feixi County, Anhui province, China
TP127	Tieqingzhima	Local resources from Baihe County, Shanxi province, China
TP128	Zihuayeersan	Local resources from Shangcai County, Henan province, China
TP129	Erlanghuazhima	Local resources from Xiping County, Henan province, China
TP130	Silengcao	Local resources from Fuyang City, Anhui province, China
TP131	Duganzhan	Local resources from Linquan County, Anhui province, China
TP132	Japan 3(32)	Varieties introduced from Japan
TP133	American U.C.R/82N	Varieties introduced from the United States
TP134	Vietnam N	Varieties introduced from Vietnam
TP135	Myanmar N.77	Varieties introduced from Myanmar
TP136	Qixianbaizhima	Local resources from Qi County, Henan province, China
TP137	Raofengbaizhima	Local resources from Raofeng Kenzhichang of Boyang County, Jiangxi province, China
TP138	Wuqingbawangbianxuan	Local resources from Wuqing County, Tianjin City, China
TP139	Cangxiansitongxuan	Local resources from Hejian City, Hebei province, China
TP140	Linyijiliganxuan	Local resources from Linyi City, Shandong province, China
TP141	Yingshangzhima-1	Local resources from Yingshang County, Anhui province, China
TP142	Xianghebawangbianxuan-1	Local resources from Xianghe County, Hebei province, China
TP143	777nongyanfa	Local resources from Guangxi province, China
TP144	Huanyuandiezhima	Local resources from Huaiyuan County, Anhui province, China
TP145	Xuanchengheizhima	Local resources from Xuancheng City, Anhui province, China
TP146	Wupuheizhima	Local resources from Wubu County, Shanxi province, China
TP147	Linxianheizhima	Local resources from Lin County, Shanxi province, China
TP148	Jixianheizhima	Local resources from Ji County, Shanxi province, China
TP149	Vietnam heizhima	Varieties introduced from Vietnam
TP150	Heizhima-2	Varieties introduced from Vietnam
TP151	CLSU-5	Varieties introduced from Philippines
TP152	T-6	Varieties introduced from India
TP153	MI-2	varieties introduced from Sri Lanka
TP154	S.K.T-20	varieties introduced from Sri Lanka
TP155	Jinzhimaxuan	Varieties introduced from Japan
TP156	Luozhi No.16	Luohe Academy of Agricultural Sciences, China
TP157	Luozhi No.18	Luohe Academy of Agricultural Sciences, China
TP158	Luozhi No.21	Luohe Academy of Agricultural Sciences, China
TP159	Zhuzhi No.1	Zhumadian Academy of Agricultural Sciences, China
TP160	Zhuzhi No.12	Zhumadian Academy of Agricultural Sciences, China
TP161	Zhongzhi No.19	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, China
TP162	Zhongzhi No.20	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, China
TP163	Zhongzhi No.24	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, China
TP164	Liutiaoji	Local resources from Zhoukou City, Henan province, China
TP165	Funanzhima No.1	Local resources from Funan County, Anhui province, China
TP166	Yingshangzhima No.1	Local resources from Yingshang County, Anhui province, China
TP167	Duijiaoma	Local resources from Wuchang County, Hubei province, China
TP168	Dutai	Local resources from Xiangyang County, Hubei province, China
TP169	Qingpinai	Local resources from Xiangyang County, Hubei province, China
TP170	Zhaogongbian	Local resources from Nanchang County, Jiangxi province, China
TP171	Yizhi No.1	Wuhan CPC Technology and New Industry Co., Ltd., China
TP172	Ethiopia baizhima	Varieties introduced from Ethiopia
TP173	Yuzhi No.11	Sesame Research Center, Henan Academy of Agricultural Sciences, China
TP174	Guozhi 235	Hefei Daguo Agricultural Biology Institute, Anhui Province, China
TP175	Jizhi No.2	Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, China
TP176	Jihangzhi No.2	Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, China
TP177	Yuzhi No.8	Henan Academy of Agricultural Sciences, China
TP178	Zhongzhi No.38	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP179	Zhongzhi No.39	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP180	Zhongzhi No.40	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP181	Zhongzhi No.42	Oil Crops Research Institute of Chinese Academy of Agricultural Sciences
TP182	Zhengzhi No.12	Henan Academy of Agricultural Sciences, China

Many cultivars exhibited a large variation for specific traits. For instance, an erect or curved capsule was observed for the cultivars ‘Zhongzhi No.12,’ ‘Xiniujiao,’ ‘Xinheheizhima,’ ‘Raofengbaizhima,’ and ‘777nongyanfa.’ For the above cultivars, the number of carpels that produced the erect type was 2 or 4, but occasionally there was 1 carpel showing the curve type. Furthermore, ‘xiangheizhi2078’ and ‘zihuayeersan’ showed the highest values in another trait, i.e., septum color. The same pattern was observed among the 183 accessions for the number of flowers per leaf axil, capsules per leaf axil, and nectary. Notably, two alien lines, i.e., ‘NA1’ from Vietnam and ‘C-50’ from India were regarded as outliners, which showed a distinct pattern in the morphological variables (Fig. 1).

A Spearman correlation matrix analysis revealed a wide range of positive and negative correlations among the studied traits (Supplementary Table S2). Strong positive or negative correlations were observed between the 1,000-seed weight and many other traits such as yield per hectare (-0.9309), stem branching pattern (-0.9552), petiole length (-0.9517), corolla length (0.9078), number of carpels (0.9096), and number of capsules per leaf axil (0.9432). The most significant negative correlations were observed among the nectary, the number of capsules per leaf axil (-1.0000), and the number of flowers per leaf axil (-0.9725). The correlation coefficient between the nectary and other characters is opposite to those for leaf axillary and other characters. The plant growth type was also positively correlated with the number of primary branches (0.8988) and stem branching pattern (0.8889). The time of flower beginning was also positively correlated with the time of terminal flowering (0.8163) and growth period (0.8808). Other significant correlations included (i) the time of final flowering was positively correlated with the growth period (0.8324); (ii) the 1,000-weight was positively or negatively correlated with protein content (− 0.8955), number of primary branches (0.8925), capsule shape (− 0.9096), presence/absence of nectary (0.8842), and seed coat texture (− 0.8539); (iii) the leaf margin was positively correlated with basal leaf degree of lobing (0.8544); the capsule thickness was associated with capsule width (0.8889) (Supplementary Table S2).

Polymorphism of the SSR markers

The number of genotypes, as detected using 25 pairs of SSR primers in the 183 sesame lines, ranged from 4 to 8, yielding a total of 166, with an average of 6.64 per primer pair (Table 2). The number of alleles detected ranged from 1.23 to 1.85, and the total number of alleles detected was 40.35, with an average of 1.614. Of these, the primer LG141 detected the largest number of alleles (1.85), while SB393 detected the least (1.23 alleles). The polymorphic information content (PIC) values varied from 0.0859 to 0.6357, with an average of 0.5254; most of the values fell within the range of 0.50–0.63. The discrimination power (DP) value indicates the ability of a primer pair to differentiate the sesame lines tested; the higher the value, the stronger the DP. The DP value of the 25 SSR primers ranged from 0.4562 to 0.8128 (mainly between 0.70 and 0.80), with an average value of 0.7205 (Table 3). The frequency of the major alleles ranged from 0.24 to 0.49 (mostly between 0.27 and 0.43), with an average of 0.34 (Table 3).

Table 2

Polymorphism of 25 SSR primer pairs in 183 sesame accessions
Primer	Polymorphic bands	I	He	HeFr	PIC	No. of genotypes	No. of alleles	DP	Major allele and its frequency	h
SB393	3	0.4986	0.3423	0.2368	0.5734	6	1.23	0.7187	130, 0.24	0.3311
LG03	3	0.6396	0.0082	0.4135	0.6156	8	1.81	0.8128	227, 0.41	0.4476
LG21	3	0.5542	0.3388	0.2841	0.5901	7	1.65	0.7676	156, 0.28	0.3742
LG22	3	0.5917	0.3144	0.3606	0.5903	8	1.74	0.7748	198, 0.36	0.4074
LG28	3	0.5709	0.3164	0.2823	0.5949	6	1.67	0.7603	155, 0.28	0.3870
LG31	3	0.5535	0.3591	0.2696	0.6007	8	1.62	0.7621	148, 0.27	0.3701
LG56	3	0.6346	0.0117	0.3370	0.6258	8	1.80	0.7632	185, 0.34	0.4429
LG57	3	0.6338	0.017	0.3625	0.6357	7	1.80	0.7819	199, 0.36	0.4425
LG40	3	0.6307	0.0171	0.3843	0.6288	7	1.79	0.7905	211, 0.38	0.4394
LG46	3	0.5554	0.3317	0.2659	0.6173	7	1.62	0.7491	146, 0.27	0.3712
LG64	3	0.5641	0.3123	0.3024	0.5718	7	1.65	0.7632	166, 0.30	0.3795
LG108	3	0.2732	0.6802	0.2568	0.0859	6	1.26	0.4562	141, 0.26	0.1659
LG111	3	0.5811	0.3315	0.4189	0.5728	7	1.73	0.7904	230, 0.42	0.3997
LG115	3	0.4500	0.4299	0.2933	0.3856	6	1.49	0.6809	161, 0.29	0.2950
LG116	3	0.4068	0.3755	0.2896	0.3570	4	1.49	0.6686	159, 0.29	0.2802
LG123	3	0.4959	0.336	0.2933	0.5097	6	1.62	0.7285	161, 0.29	0.3380
LG141	3	0.6497	0.0062	0.4372	0.6325	4	1.85	0.6981	240, 0.44	0.4573
LG131	3	0.5064	0.3337	0.3515	0.5070	7	1.67	0.7598	193, 0.35	0.3507
LG144	3	0.5407	0.4422	0.2896	0.5145	8	1.61	0.7122	159, 0.29	0.3601
LG139	3	0.6105	0.1301	0.3206	0.6313	8	1.75	0.8027	176, 0.32	0.4214
LG140	3	0.5260	0.5397	0.2586	0.5702	7	1.58	0.7168	142, 0.26	0.3472
LG148	3	0.3707	0.7948	0.3898	0.2955	6	1.29	0.5218	214, 0.39	0.2186
LG147	3	0.5430	0.3733	0.4317	0.4735	6	1.60	0.7521	237, 0.43	0.3611
LG151	3	0.3845	0.6384	0.4918	0.4778	6	1.42	0.5525	270, 0.49	0.2511
LG153	3	0.4651	0.3348	0.3698	0.4787	6	1.61	0.7279	203, 0.37	0.3237

Note: I, Shannon’s index; PIC, Polymorphic information content; He, Heterozygosity, HeFr, Heterozygous gene frequency, DP, Discrimination power; h, Gene diversity.

DNA fingerprinting of 183 accessions

The frequency of heterozygous genotypes in the sesame lines varied from 0.05 to 0.51, with an average of 0.34, and the frequency of the heterozygous genotypes ranged from 0.31 to 0.46. There were 53 (28.96%) lines with heterozygotic genotype frequency of < 0.31, 115 (62.84%) lines between 0.31 and 0.46, and only 15 (8.20%) lines of > 0.46 (Fig. 2).

There was a total of 1,6653 line-by-line comparisons, of which the number of different sites within two given lines ranged from 4 to 44, and 90.35% of the number of different sites ranged from 15 to 34 (Fig. 3). There were only 8 pairs of lines with different site numbers smaller than 5. In addition, 4, 1, and 3 pairs of lines had different site numbers of 3, 4, and 5, respectively. Moreover, 37 pairs of lines had different site numbers that were more than 40, and 20, 11, 5, 0, and 1 pair showed 40, 41, 42, 43, and 44 different sites, respectively. Finally, there were at least three different loci for any two lines, indicating that this set of SSR markers has the power to differentiate any of the 183 lines tested.

Genetic diversity analysis of sesame lines with different origins

To explore the genetic architecture of the 183 lines, we first empirically divided them into three groups based on their origins, i.e., Chinese cultivars (CC) released in the past decades, Chinese landraces (CL), and alien accessions from other countries (AA). Then the genetic diversity parameters for each group were analyzed (Table 3). For each group, the total number of genotypes ranged from 129 to 130, and the total number of alleles from 117 to 121. The number of lines in the AA and CL groups was significantly less than those of the CC group, but the total number of alleles was comparable to or slightly higher than those of the CC group. The number of lines in the CC group was as high as 101, accounting for 55.19% of all lines, but the total number of genotypes and alleles detected was lower than those in the CL group. The average frequency of the heterozygous genotypes in the three groups ranged from 0.3219 to 0.3667, with the highest frequency of heterozygotic genotypes observed in the AA group (0.3667) and the lowest in the CL group (0.3219). Genetic diversity is the sum of the genetic variation detected using 25 pairs of SSR primers for different lines within a group, which was used as an index reflecting the differences in terms of genetic diversity among the different groups. The results showed that gene diversity varied from 0.3454 to 0.3515, and the CL group was slightly higher than the CC and AA groups.

Table 3

Comparison of genetic diversity among three different origin groups
Groups	Number of lines	Number of genotypes	Number of alleles	Heterozygous genotype rate	Gene diversity
Chinese varieties	101	130	120	0.3379	0.3454
Chinese landraces	62	130	121	03219	0.3515
exotic accessions	20	129	117	0.3667	0.3499

Systematic cluster analysis of 183 sesame varieties

A systematic cluster analysis was performed using SSR markers for the 183 sesame accessions (Fig. 4), which generated three major classes. Class I consisted of 68 lines including AA and CL from north China, all of which have black or brown grain color, a single flower in the leaf axils, easy branching, and low yield. The growth period of these lines was either too long or too short, and thus not very suitable for cultivation in the major sesame-producing areas in China, i.e., Jianghuai Area (downstream of the Yangtzi and Huihe rivers). Although these lines are resilient to waterlogging, they are very sensitive to drought and heat stresses, which can lead to premature aging. They are easily infected by stem point blight and blight in rainy years, which in turn affects their yield potential. Class II comprised 73 CC in the ‘Zhongzhi,’ ‘Ezhi,’ ‘Luozhi,’ and ‘Zhuzhi’ series, and some CL collected from Jiangxi, Anhui, and other provinces in China. These lines exhibit single stems, three flowers per leaf axilla, white grains, and moderate growth periods, which makes them very suitable for cultivation in the Jianghuai area in China. The tolerance to waterlogging, drought, and biotic stresses has greatly improved in these lines, so they produce the highest yield per unit area in China. Class III consisted of 42 CC, including the ‘Zhongzhi,’ ‘Wanzhi,’ and ‘Ganzhi’ series cultivars, and several CL from the Yunnan and Guangxi provinces in China, most of which have a single stem, three flowers per leaf axilla, white grains, and slightly longer growth periods, and are suitable for cultivation in the Jianghuai Valley and Southern China. They are strongly tolerant to rain but poorly tolerant to drought, making them more suitable for cultivation in poor fields, but with moderately high yields.

Principal coordinate analysis of 183 sesame lines

To show the relationships among each group of varieties more clearly, the principal coordinates of the 183 sesame varieties were analyzed based on the clustering results (Fig. 5). According to the distribution of each group of varieties in Fig. 4, the PCA plot was divided into four areas, namely I, II, III, and IV. The main distribution quadrant I represented CC of the ‘Zhongzhi,’ ‘Ezhi,’ ‘Luozhi,’ and ‘Zhuzhi’ series, and some CL from the Jiangxi and Anhui provinces in China, and can be separated from the other two classes. The genetic distance among such genotypes is close, as indicated by high similarity coefficients and small kinship values. Meanwhile, the cultivars of the ‘Zhongzhi,’ ‘Wanzhi,’ and ‘Ganzhi’ series were mainly distributed in the quadrant IV area. CL and AA with long or short growth periods, axillary single flowers per leaf, and easy branching were mainly distributed in the quadrant II and III regions. The distribution of the varieties in quadrant I was relatively concentrated, indicating that the genetic differences among these lines are small, and most of them are cultivars released in recent decades. Since several common elite lines have been used as parents in breeding practice, the resultant cultivars showed a close genetic relationship with each other, as reflected by the small genetic differences. Most of the CL were located in the quadrant II area, and the AA were assigned to the quadrant III area, with a few lines distributed across the quadrant IV area.

The base components, sequence, and length of the genetic material DNA of different varieties of the same crop are different and show their unique DNA sequence characteristics. As they have the same specificity as human fingerprints, their identification ability is comparable to fingerprints; therefore, they are also called DNA fingerprints. The establishment of a comprehensive and accurate fingerprint database of cultivated varieties can provide unique and specific identification data support for the trial approval of varieties and the protection of new plant variety rights, provide real and reliable identification and comparison data for seed market monitoring, and have a certain guiding effect on the adjustment of breeding strategies. China is one of the major producers of sesame, and the yield per unit area is ranked high in the world. Before 2015, only a few new cultivars were released each year in China. However, after the promulgation of the new Seed Law in China in 2015, the number of registered varieties increased rapidly to 60 or more each year, which led to chaos in the sesame seed market due to variety infringement. To protect the legitimate rights and interests of breeders, this study aimed to construct a fingerprint database of sesame cultivars in China to provide data and identification basis for the protection, registration, management, and market monitoring of new varieties. Compared with the results of the sesame variety analysis by Liu et al. [15], the number of alleles, genotype numbers, PIC values, and gene diversity improved in this study. There are several explanations for this. First, to construct and analyze the difference in the number of varieties, this study constructed a fingerprint database of 183 varieties, which is double the number of lines in previous studies [15]. Second, the number and class of primers adopted had many differences. In this study, 25 pairs of SSR primers were used, while 10 pairs of AFLP primers were used by Liu et al. [15], Third, the genetic background of the sesame genotypes in this study was richer, which included AA, CL, and released cultivars. The utilization of genetic stocks from China and foreign countries has further broadened the genetic diversity of CC. The average frequency of the total heterozygous genotype of the tested lines was 0.3357, and that of the cultivars was 0.3379. The average frequency of the heterozygous genotypes of all lines was less than 0.5, indicating that the cultivars were mostly configurated cross combinations with relatively close relatives. The differences between the 183 lines were statistically analyzed. The results indicated that the number of different sites among cultivars was ≥ 4, mainly concentrated between 15 and 34, and only 8 pairs of combinations had 4–5 differential loci. With the rapid increase in cultivars released, similar varieties and derived varieties are also gradually increasing. Therefore, the number of markers and the standardization of DNA fingerprints are also required to be significantly improved. SSR markers are abundant and randomly distributed in the genome; they show codominance, high allelic variation, simple operation, and good stability, and have been used successfully in the identification of soybean [16], apple [17], grape [18], and other varieties. However, with the increased number of cultivars needed to be tested, more markers, and higher detection throughput, integration and sharing of fingerprint data should be implemented. SNP is a third-generation marker, which can be arrayed in a chip with 50,000–90,000 markers; it can greatly improve the accuracy of the authenticity identification of crop varieties, detect thousands of samples simultaneously, make it easier to perform data integration analysis, and greatly reduce detection costs. Therefore, the SNP marker should be developed and applied to sesame variety identification.

An assessment of the genetic diversity of sesame varieties in China can objectively and comprehensively reflect the research status of sesame varieties in China and is of great significance for the cultivation of new varieties and the innovative utilization of germplasm. In this study, germplasm resources and cultivated varieties in China and foreign lands were analyzed from the aspects of genetic parameter statistics, systematic clustering, and principal coordinate distribution. The clustering results showed that resource aggregation in different regions intersected with each other and was not directly related to geographical distribution, which was consistent with the results of domestic and foreign studies [19], and the genetic diversity of germplasm resources was relatively rich. The results of this study show that the genetic distance range of the tested plant materials was from 0.1278 to 0.8400. Of these, the genetic distance between the new variety ‘Zhongzhi No. 18’ bred by the Oil Crops Research Institute of CAAS, and the variety ‘Xiangzhi No. 2’ by Xiangyang Polytechnical College was the smallest. The genetic distance between the landraces from Wulonghei of Jiangxi Province and the variety ‘Zhongzhi No.13’ bred by the Oil Crops Research Institute of CAAS was the largest. The results of the binary principal coordinate analysis showed that the varieties of the ‘Zhongzhi’, ‘Ezhi’, ‘Luozhi’, and ‘Zhuzhi’ series were gathered in one group, which means that they have closer genetic distance and relatively narrow genetic basis with the landraces collected in Jiangxi and Anhui provinces of China.

In this study, we also found that among the varieties release in China, the ‘Ganzhi’ series varieties were more concentrated together, indicating that the parental materials used by breeders are closely related, and the genetic basis of the new varieties is narrow. The reason may be that ‘Ganzhi No.2’, ‘Ganzhi No.5’, ‘Ganzhi No.6’, ‘Ganzhi No.7’, ‘Ganzhi No.8’, and’ Ganzhi No.9’ are all black sesame, and they were all selected or mutagenic from black seed-coat sesame landrace from Jiangxi Province, China. For example, ‘Ganzhi No.2’ was selected from the black sesame series of Boyang landrace, ‘Ganzhi No.5’ was selected from the Jiangxi local resource ‘Jinhuangma’ series, ‘Ganzhi No.7’ was selected from the Jinxian local resource ‘Zhaogongbian’ series, ‘Ganzhi No.8’ was selected from the Jinxian local resource ‘Jingchaima’ series, and ‘Ganzhi No.9’ was mutagenic from the Jiangxi local resource ‘Wuningheijing’ by ⁶⁰Co-γ. Sesame is a self-pollinating crop, but it has a natural outcrossing rate: the natural outcrossing rate of foreign sesame range from 1–65% [20–22], and the natural outcrossing rate of Chinese domestic sesame range from 5.13–23.35% [23]. These local resources may have cross-pollinated from each other due to years of cultivation together, and some genes are introgressed into the modern varieties. Some of the ‘Zhongzhi’ series varieties are clustered together with the ‘Wanzhi’ series varieties, such as ‘Zhongzhi No.11’, ‘Zhongzhi No.12’, ‘Zhongzhi No.13’, ‘Yuzhi No.7’, ‘Wanzhi No.1’, and ‘Wanzhi No.2’, which are all derived from ‘Yiyangbai’ or the derivative variety of ‘Yiyangbai’; this result is highly consistent with that of Yue et al. [19]. Therefore, to promote the breeding progress of sesame varieties in China, the rich sesame resources preserved in China should be exploited as parents for cross-breeding, and at the same time, the crossing between varieties collected from different geographic regions should be strengthened to expand the genetic diversity of breeding lines.

This study shows that the genetic diversity of germplasm resources in China is relatively higher than that of foreign germplasm resources, which may be related to the small number of foreign materials selected in this study. The geographical sources of the 20 foreign resources are mainly concentrated in Asia and Africa. The lack of regional resources, such as resources from Europe and the Americas, and the closeness of the geographical location resulted in the resources not showing good characteristics of genetic diversity. Comparing the genetic distance between the foreign and domestic resources, the results show that China’s sesame landrace ‘Lushibaizhima’ and ‘Beijingbawangbian’ have the closest genetic relationship with the Indian SVPR1. Therefore, it can be concluded that Chinese sesame may have been introduced from India, while China’s sesame resources are ‘Zhushanbai’, ‘Xiniujiao’, ‘Hongmaoqiu’, ‘Vietnam NA1’, ‘Kaixianbaizhima’, Yunnan ‘Honghebaizhima’, and Japan 3(32). The genetic relationship between ‘Hongmaoqiu’ and ‘Wangmobaizhima’ and T-6 is the furthest. Hence, we can conclude that most of the Chinese sesame resources are not from Vietnam and Japan. This result is inconsistent with that of Yue et al. [19], who indicated that Chinese sesame may have been introduced from America. This could be due to the lack of materials in this study. China’s sesame germplasm resources medium-term bank (Oil Crops Research Institute of the CAAS, Wuhan) has preserved 8,960 sesame germplasm resources; the domestic resources also have rich genetic diversity. In conclusion, we recommend that China should strengthen the introduction of foreign resources and the distribution and utilization of domestic resources to promote the breeding and popularization of new sesame varieties in China in the future.

At present, about 8960 sesame germplasm resources have been preserved in China. Therefore, the development of the sesame industry needs to explore and utilize excellent germplasm resources. A DNA fingerprint database of 183 sesame varieties and germplasm resources was constructed, and a corresponding two-dimensional code was developed. The polymorphic information index ranged from 0.0859 to 0.6357, with an average value of 0.5254, and the average heterozygosity (He) was 0.3246. The 183 sesame accessions were categorized into three UPGMA groups. The genetic diversity coefficient of sesame germplasm is generally small, and the genetic relativeness is close. The genetic diversity coefficient of Chinese accessions is not much different from that of foreign resources.

Plant materials used in this study

The plant materials used in this study comprised 101 cultivated sesame varieties and 62 landraces from China, as well as 20 accessions from Asia, Africa, and America (Table 1). All these sesame lines were obtained from the Chinese Midterm Oil Crops GenBank attached to the Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences (CAAS) and the Xiangyang Academy of Agricultural Sciences in China.

Morpho-physiological analysis of sesame

For the morpho-physiological analysis of the 183 lines, field experiments were carried out for two consecutive growing seasons at the experimental station of CAAS. Plants were grown in 2.4 m plots with a row-to-row spacing of 0.4 m and plant-to-plant spacing of 0.15 m. Five plants were randomly selected and tagged in each plot to determine the agronomical traits. A total of 56 morphological and agronomical characteristics related to growth, branching, leaf and stem morphology, flower, capsule, and seed traits, as well as flowering time and seed maturity were recorded for each plant based on the descriptors and data standard for sesame [24]. The raw data of the qualitative characteristics are presented in Supplementary Table S1.

Total DNA extraction

Sesame seeds were cultivated and grown in a plant growth chamber at 25°C for 10 days. Fifteen seedlings per line were collected for total DNA extraction using the CTAB method [25]. In brief, 1.0 mL extraction buffer was added to a grinding bowl and quickly ground the seedlings into a homogenate, and kept in a water bath at 60°C for 1 h. Next, an equal volume of chloroform: isopropanol mixture (24:1) was added, reversely mixed several times, and then centrifuged at 1,2000 r/min for 15 min to collect the supernatant. Afterward, frozen absolute ethanol was added to precipitate the DNA. Finally, the DNA precipitate was rinsed l–2 times with 76% ethanol, dried at about 25°C, and dissolved with TE buffer. Two microliters of the mixture were used for electrophoresis to measure its mass and concentration, and then the DNA concentration was uniformly adjusted to 25 ng/µL.

Simple sequence repeat (SSR) primer sequences and PCR amplification

Twenty pairs of SSR primers were selected from previous studies [26, 27] and synthesized by Sangon Biotech (Shanghai) Co., Ltd (Supplementary Table S3). PCR amplifications were carried out in a 10-µL reaction volume containing 2.5 µL of genomic DNA (25 ng/µL), 0.9 µL each of forward and reverse primers (50 ng/µL), 1.2 µL of Mg²⁺ (25 mmol/L), 0.3 µL of dNTPs (10 mmol/L), 0.3 µL of Taq enzyme (5 U/µL), 0.7 µL of 10× reaction buffer, and 4.1 µL of ddH₂O. The PCR reactions were performed in an MJ PTC100 Thermocycler (Thermo Fisher Scientific Inc., USA) using the following procedure: one cycle of 3 min at 94°C followed by 40 cycles of 30 s at 94°C, 30 s at 60°C, 45 s at 72°C, and a final incubation at 72°C for 5 min and 4°C thereafter. The PCR products were size-separated on 6% denaturing polyacrylamide gels and visualized using silver staining.

PCR amplification was performed for the 183 sesame lines, and each primer was amplified at least three times. To prevent the phenomenon of inconsistent data reading due to high or low and continuous peaks, each group of experimental data was read by two people independently. The comparison of the experimental data and manual proofreading was then carried out. Finally, a set of fingerprint data with 100% integrity was formed.

Data analysis

The morpho-physiological data were analyzed using HEMI software [28] and the web tool ClustVis for the hierarchical clustering heatmap. For the classification of accessions based on the qualitative traits, principal component analysis (PCA) was applied after the standardization of the variables, and the Spearman coefficient was used to assess the correlation among the variables. The covariance matrix was then used to determine the principal components of the data. Within the PCA, factor loadings higher than 0.55 were regarded as significant, and biplots were constructed about the first two most important principal components. In addition, Ward’s method was used for agglomerative hierarchical clustering [29].

The electrophoresis bands were read manually. The clear bands at the same position were recorded as 1 and those without bands as 0. Based on the morphological traits and SSR marker data, the following indexes were calculated: (1) The number of alleles, polymorphism information content value, the distinguishing ability of the primer, and the Shannon index of each primer pair; (2) the frequency of the heterozygous genotypes and the number of different sites between pairs; (3) the number of lines assigned to the three groups, and the total number of alleles, average frequency of heterozygous genes, and gene diversity values for each group. The above data were statistically analyzed using Popgene32 software [30].

To further study the genetic relationship between sesame germplasm and the Chinese cultivated varieties, the genetic distance, systematic clustering, and principal coordinate analysis were carried out for the 183 lines. NTSYSpc 2.1 was used to build an unweighted pair-group method with arithmetic averaging clustering tree and the binary principal component was analyzed. By combining the above genetic distance matrix and systematic clustering results, coordinate analysis of the 183 sesame lines was carried out in R language, and scatter plots were drawn.

Acknowledgments

We thank the editors and reviewers for their careful reading and valuable comments. We apologize to researchers whose studies are not cited due to space limitations.

Author’s contributions

ZW and FZ performed the investigation and analyzed data and draft the manuscript. XT, YY and TZ provided resources and carried out experiments and data analysis. HL contributed to conceptualization, supervision, funding acquisition, and manuscript editing.

Funding

This study was supported by funds from the National Natural Science Foundation of China (Grant No. 31771877), the Agriculture Research System of China (Grant No. CARS-14), and the Agricultural Science and Technology Innovation Program, CAAS (Grant No. CAAS-ASTIP-2013-OCRI).

Data Availability

The datasets supporting the conclusions of this article are included within the article and its additional files.

Declarations

Ethics approval and consent to participate

All plant materials used in this study were grown and collected according to institutional and national guidelines. All methods complied with relevant institutional, national, and international guidelines and legislation.

Consent for publication

Not applicable.

Competing Interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Morphology and SSR markers-based genetic diversity analysis of sesame varieties released in China

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Abstract

Figures

Background

Results

Morphological and agronomical diversity of the sesame accessions

Polymorphism of the SSR markers

DNA fingerprinting of 183 accessions

Genetic diversity analysis of sesame lines with different origins

Systematic cluster analysis of 183 sesame varieties

Principal coordinate analysis of 183 sesame lines

Discussion

Conclusion

Materials and methods

Plant materials used in this study

Morpho-physiological analysis of sesame

Total DNA extraction

Simple sequence repeat (SSR) primer sequences and PCR amplification

Data analysis

Declarations

References

Additional Declarations

Supplementary Files

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