How does population outcrossing rate influence seed quality? Evidence from a 58-year-old seed tree stand of Pinus massoniana

doi:10.21203/rs.3.rs-2132364/v1

Download PDF

Research Article

How does population outcrossing rate influence seed quality? Evidence from a 58-year-old seed tree stand of Pinus massoniana

https://doi.org/10.21203/rs.3.rs-2132364/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

Inbreeding is thought to be a key adverse factor impacting the genetic quality of seeds in seed production populations and the inbreeding degree (i.e., selfing or outcrossing rate) of seed production populations have been extensively assessed through mating system analysis. The depression effect of inbreeding on seed quality traits in seed production populations under open-pollination conditions has not yet been clearly described. In this study, the open-pollinated seeds were collected from 26 mother trees in a 58-year-old seed tree stand. Three seed quality traits, including thousand-seed weight (TSW), germination rate (GR) and germination potential (GP), were measured, and the seeds from eight of 26 families with significant differences in seed quality traits were genotyped through twelve microsatellite markers. In addition, the seeds and sprouts (germinated seeds) from six families were genotyped to reveal the effect of inbreeding on seed germination. The three seed quality traits significantly differed among families (p<0.001). The multilocus outcrossing rate (t_m= 0.889) and single-locus outcrossing rate (t_s = 0.648) of overall seeds indicated apparent selfing (11.1%) and biparental inbreeding (24.0%). The outcrossing rate in the sprout group (t_m= 0.919, t_s= 0.788) was higher than that in the seed group (t_m = 0.833, t_s = 0.646), and the difference in t_s between groups was different from zero under the 95% confidence interval (0.024-0.260), suggesting that inbreeding negatively affected seed germination. Linear regression demonstrated that TSW was positively correlated with t_m and t_s, while GR was negatively related to t_m-t_s and positively related to t_s, implying that seed mass (development) was probably more affected by self-fertilization, but germination capacity was more influenced by biparental inbreeding. Roughly, the inbreeding depression (ID) of TSW was 26.3% with a 0.1 decrease in t_m, while GR was 8.4% with a 0.1 decrease in t_s. In summary, these results suggest that the IDs during seed development and the germination stage of Masson pine were nonignorable and that more attention should be given to the establishment and management of Masson pine seed production.

inbreeding depression

seed viability

outcrossing rate

Pinus massoniana Lamb

Self-pollination and mating among relatives can depress offspring fitness traits and population viability in natural outcrossing species. These effects are known as inbreeding depression (ID). There are five categories of mating patterns (predominantly selfing, predominantly outcrossing, mixed selfing and outcrossing, apomixis and intragametophytic selfing) in plants under natural conditions(Brown 1990). Of these, mixed mating systems are relatively common(Griffin et al. 2019). Mainly long-lived perennials, such as coniferous tree species(Mitton 1992), have mixed mating systems. Inbreeding depression prevalently occurs in mixed mating species(Williams and Savolainen 1996; Nakanishi et al. 2015). The ID arises at the stages of seed production of the parent, seed development and germination, juvenile survival, and growth(Husband and Schemske 1996). Many studies in tree species reported variable levels of ID among phenotypic traits during juvenile survival and growth(Duminil et al. 2016; Moraes et al. 2018; Pupin et al. 2019; Takeuchi et al. 2020). In Eucalyptus globulus, the average ID of selfing progenies was detected from 22 to 27% on growth in the first 4 years(Nickolas et al. 2019). There was a 19.6% biomass reduction in inbred individuals of white bark pine (Pinus albicaulis)(Bower and Aitken 2007) and an approximately 8.1–12.4% ID on root collar circumference and plant height of full-sib offspring in Balfourodendron riedelianum(Aguiar et al. 2020). The ID levels of seed quality traits (percentage of full seeds, seed weight, germination rate, germination potential, etc.) were studied in some species through controlled mating among individuals with different siblings (i.e., self, full-sib, half-sib, cousins and unrelated mating)(Mullin et al. 2019), and many tree species appeared to have severe effects of ID during seed development(Husband and Schemske 1996; Stacy 2001; Salzer and Gugerli 2012).

The open-pollination seed production population (such as seed orchards and seed-tree stands) is a common approach for commercial seed supply in many countries to date. The inbreeding levels of such seed production populations are affected by many factors in tree species, including the variation in female and male fertility with year and tree ages, variation in reproductive phenology(Muñoz-Gutiérrez et al. 2019), pollen dispersal distance(Duminil et al. 2016), and population size(Castilleja Sánchez et al. 2016). Although it is generally believed that inbreeding (especially selfing) in seed production populations affects the genetic quality of seeds, few studies have directly investigated the correlations between inbreeding degree (selfing or outcrossing rate) and seed quality. The effect of inbreeding on seed quality traits in seed production stands of many tree species is still unclear. Bridging the knowledge gap between seed quality traits and inbreeding (or outcrossing) levels of seed production populations is undoubtedly essential to seed yield and quality management.

Masson pine (Pinus massoniana Lamb.) is a commercially and ecologically important coniferous tree species for timber production, carbon storage, and other ecological services and is geographically widely distributed in central and southern China. The genetic variation and mating system of Masson pine seed production populations (e.g., seed orchards) have been analysed(Ai et al. 2006; Zhang et al. 2008; Tan 2011). A seed orchard of 16-year-old Masson pine was found to exhibit high outcrossing rates, and both the parental and progeny populations showed high genetic diversity(Zhang et al. 2008). It was reported that biparental inbreeding was not significant and that outcrossing was the primary mating mode in a clonal seed orchard of Masson pine(Feng et al. 2017). A seed-tree stand of Masson pine and its four progeny populations generated at 37–55 years showed similar genetic diversity, while the differentiation seemed to be increased by nonrandom mating (inbreeding and pollen contamination, etc.)(Bai et al. 2021). However, all of the above results were detected in seedlings rather than seeds, and the inbreeding effect during seed development and germination was largely neglected. The ID in the seed development and germination phases unavoidably influences the actual yield of the seed production population. Here, we assessed the quality of open-pollinated seeds from a 58-year-old Masson pine seed-tree stand. The seeds were genotyped using microsatellite markers to analyse (1) the seed quality variation between seed trees; (2) the mating system of the current seed-tree stand; and (3) the correlation between outcrossing rates and the seed quality indicators (seed weight and viability). We aimed to investigate whether the variations in seed quality were influenced by the outcrossing (or selfing) rate, which provides implications for the establishment and management decision-making of seed production populations.

Plant material

A total of 26 seed trees were randomly sampled from a 58-year-old seed tree stand of Masson pine. The establishment information of this stand was elaborated in Bai et al. (2021). Thirty mature cones were randomly collected from the upper crown of each mother tree in mid-November 2018. The cones were exposed to sunlight, and the shed seeds were collected and dewinged and then stored at 4°C for further analysis. All voucher specimens were preserved in the Forestry College of Guangxi University.

Seed quality measurement

Three predominant indicators, thousand-seed weight (TSW), germination rate (GR) and germination potential (GP), were measured to evaluate the seed quality of the mother tree. Four replicates of 200 seeds were randomly taken from each seed tree and weighed separately to calculate the TSW. Four replicates of 100 seeds were selected and sterilized with a potassium permanganate solution of 0.05% for 12 h. After rinsing in distilled water several times, seeds were evenly laid in germination boxes lined with two sheets of filter paper, moistened with deionized water, and then placed in an incubator. The incubator programs were changed between daytime and nighttime. The night temperature was set at 20 ± 1℃ with an illumination intensity of 0 Lux, while the daytime temperature was 22 ± 1℃, with 1000 Lux. Daily observations and recordings were made for the calculation of GR. The germination testing lasted 25 days (from March 3, 2019, to March 28, 2019). GR and GP were calculated according to the following formulas:

GR (%) = (number of seeds germinated/total number of seeds tested) ×100

GP (%) = (number of seeds germinated when germination reached its peak/total number of seeds tested) ×100

After germination, the germinated seeds (sprouts) of each family were collected into 1.5 ml PE tubes and stored at -80°C for further genotyping.

DNA extraction and genotyping

In total, 220 offspring from eight of the 26 aforementioned mother trees, including six trees with 15 seeds plus 15 sprouts per tree and two trees with 20 seeds, were used for DNA extraction. Only seeds were used for the latter two mother trees because their germination was very low. The DNA in each seed was isolated according to the method of Kuang et al. (2010). Twelve microsatellite markers from Bai (2013) were selected for genotyping. The primer information is provided in the Supplemental material I.

PCR was performed in a total volume of 10 µL containing 50 ng of DNA, 10 mM 10 × buffer (containing Mg²⁺) and 0.25 mM dNTPs, forward and reverse primers at 0.3 µM, 0.5 U of Taq polymerase (Takara Biomedical Technology Co., Ltd, Beijing), and ultrapure water was added to bring the total to 10 µl. All amplification reactions were performed in a Biometra TGradient PCR 96 instrument (Germany) by using a modified touchdown protocol according to Ni et al. (2015): 94°C for 5 min; 10 cycles of 94°C for 30 s; touchdown at 60°C decreasing to 51°C at 1°C per cycle for 30 s; 30 s at 72°C; 20 cycles of 30 s at 94°C, 30 s at 52°C, and 30 s at 72°C; and a final extension at 72°C for 5 min then final storage at 4°C. The PCR product was separated by an 8% denatured polyacrylamide gel, detected and genotyped by using GelJ software (HERAS J. et al., 2015) and then manually adjusted for analysis.

Data analysis

Analysis of variance (ANOVA) was performed on seed quality indicators (TSW, GR, and GP) using R 3.4.1(R Core Team 2020), and the percentages were transformed to arcsine square root values before analysis to make a normal error distribution (Sabin et al. 1990). The mating system was analysed by MTLR 3.4 software (Ritland 2002) under mixed mating systems, and the estimated parameters included the multilocus outcrossing rates (t_m), single-locus outcrossing rates (t_s), single-locus (r_p(s)) and multilocus (r_p(m)) correlation among parental trees, correlation of selfing among families (r_s), and mating among relatives (t_m – t_s). All parameters were estimated by the expectation-maximization (EM) algorithm. The standard error of these estimators was evaluated through 1000 bootstrap replicates. Linear regression analysis was performed to explore the effect of t_m, t_s and t_m – t_s on TSW, GR and GP. Logistic regression analysis, which is more suitable for biological data, was also performed between seed quality traits and t_m, t_s, and t_m – t_s using the R package drc (Ritz et al. 2015). The percentage of inbreeding depression (ID) of seed quality indicators due to outcrossing rate decline was estimated as:

ID (%) = 100⋅ b ⋅\(\frac{1-t}{{\stackrel{-}{x}}_{t=1}}\)

where b is the slope of the linear regression equation, t is the value of the outcrossing rate (t_m or t_s), and \({\stackrel{-}{x}}_{t=1}\) is the expected value of a given trait estimated through the regression equation under the hypothesis of no inbreeding (i.e., the outcrossing rate equal to one).

Seed quality variation

The average thousand-seed weight (TSW), germination rate (GR), and germination potential (GP) were 8.49 g, 69.77%, and 44.77%, respectively. The TSW, GR and TSW were variable and significantly different among the seed trees (families) according to the ANOVA results (Fig. 1). Of the 26 families, FM078 had the highest TSW (12.66 g), GR (91.50%) and GP (68.50%). FM112 had the lowest TSW (4.75 g), and FM002 had the lowest GR (34.00%) and GP (12.50%).

Mating system

A total of 220 offspring (containing 130 seeds and 90 sprouts) from eight families (red colour in Fig. 1) were genotyped. The multilocus outcrossing rates (t_m) were 0.889 (Table 1), implying that some seeds (10.8%) were inbred due to self-fertilization. The mating among relatives (t_m-t_s), selfing correlation (r_s), and multilocus correlated paternity (r_p(m)) was 0.240, 0.594, and 0.617, respectively, indicating a nonnegligible proportion of biparental inbreeding, and a few male parents supplied a large number of pollen to the same mother trees, resulting in a high proportion of full sibling offspring.

To explore whether the outcrossing rate has an effect on the germination ability of seeds, the outcrossing rates of seeds (without performing the germination test, Group I) and sprouts (germinated seeds, Group II) from six common families were compared. The t_m (0.833) and t_s (0.646) of seeds were lower than those of sprouts (t_m = 0.919 and t_s = 0.788) (Table 1), although there was no statistically significant difference in t_m and a weakly significant difference in t_s between the two groups under 95% confidence intervals (t_m:-0.032 to 0.204; t_s: 0.024 to 0.260). The value of mating among relatives (t_m-t_s) in the two groups was significantly larger than zero, and that value of the sprouts was marginally lower than that of seeds (0.056). Similarly, the values of r_s and r_p(m) in sprouts were slightly smaller than those in seeds. This result was consistent with the expectation that the sprout group was more from outcrossing seeds and had a larger effective number of pollen donors due to eliminating the ungerminated seeds from inbreeding (selfing and mating among relatives).

Table 1

Mating system parameters of eight Masson pine families using 12 microsatellite loci
Index	Overall	Seeds (Group I)	Sprouts (Group II)	Difference between group I and II
Number of families (seeds/sprouts)	8 (220)	6 (90)	6 (90)
Multilocus outcrossing rates (t_m)	0.889 (0.028)	0.833 (0.046)	0.919 (0.038)	0.086 (0.060)
Single outcrossing rates (t_s)	0.648 (0.028)	0.646 (0.040)	0.788 (0.040)	0.142 (0.060)
Mating among relatives (t_m-t_s)	0.240 (0.020)	0.187 (0.029)	0.131 (0.031)	-0.056 (0.044)
Correlation of selfing among families (r_s)	0.594 (0.082)	0.474 (0.111)	0.235 (0.101)	-0.240 (0.152)
Multilocus correlated paternity (r_p(m))	0.617 (0.046)	0.713 (0.089)	0.625 (0.085)	-0.088 (0.134)
Single locus correlated paternity (r_p(s))	0.484 (0.052)	0.363 (0.059)	0.495 (0.069)

The values in brackets are the standard error estimated with 1000 bootstrap replicates.

Relationship between the outcrossing rate and seed quality.

Linear regression demonstrated that the TSW increased remarkably with increasing t_m and t_s. The GR increased with t_s and decreased with t_m-t_s (Fig. 2). Roughly, the predicted value of TSW would be reduced by 2.89 g (ID = 26.3%) and by 1.50 g (ID = 12.6%) with the 0.1 decrease in t_m and t_s. Correspondingly, there were ID values of 8.4% and 16.4% on GR, with t_s and t_m-t_s decreasing by 0.1. Logistic regression also detected a significant positive effect of t_m on TSW (PseudoR² = 0.78) and a negative effect of t_m-t_s on GR (PseudoR² = 0.29) (Supplemental material II), suggesting, again, that TSW and GR were negatively influenced by selfing or biparental inbreeding.

Variation in seed quality among seed trees

Seed quality is essential for seedling establishment and reforestation. To date, studies referring to seed quality assessment for Masson pine seed production populations are scarce (Xu et al. 2004). Our study displayed a great deal of heterogeneity in seed quality traits (TSW, GR and GP) among mother trees within a 58-year-old Masson pine seed stand. Seed mass and germination capacity are considered important indicators of seed quality (Mamo et al. 2006; Prochazkova 2009; Oliver and Borja 2010; Tumpa et al. 2021). The seed mass of many species was positively correlated with germination time and early seedling performance (Loha et al. 2006; Gomaa and Picó 2011; Suárez-Vidal et al. 2017), and heavy seeds exhibited greater adaptability to environmental stress than lighter seeds (Pringle et al. 2007; Calvo et al. 2016; Muñoz et al. 2017), even though contrary results were reported in some species (Mamo et al. 2006; Baskin and Baskin 2015). The seed morphometric and quality traits of many tree species are variable between (provenances) and within populations (Andersen et al. 2008; Oliver and Borja 2010; Calvo et al. 2016; Suárez-Vidal et al. 2017). The variation in seed quality traits within a seed production population is probably more influenced by genetic factors (inbreeding, interior pollen contamination, and genetic heterogeneity among seed trees) than by the environment (habitat stress) because the seed stand is in a relatively similar environment and under uniform management. Inbreeding due to pollen shortage, variation in fertility, asynchronism in reproductive phenology, and the relationship among neighbouring trees have been reported in some species (Hirayama et al. 2005; Gonzaga et al. 2016; Muñoz-Gutiérrez et al. 2019; Pupin et al. 2019). In addition, the reproductive capacity of forest trees varies with tree age, and if the seed trees are too old, the yield and quality of seeds produced will be negatively affected (Ganatsas et al. 2008; Callejas-Díaz et al. 2022). The seed stand in our study is 58 years old, older than most of the reported Masson pine seed production populations thus far (Ai et al. 2006; Zhang et al. 2008; Tan 2011). Its reproductive capacity probably declines and thus intensifies nonrandom mating, even though the actual age of the blooming reproduction period of Masson pine is still unknown (Bai et al. 2021).

Mating system and inbreeding depression

The evaluation of inbreeding degree and effect is crucial for seed production population management. Our observations demonstrated significant selfing and biparental inbreeding in Masson pine seed tree stands (t_m = 0.889, t_s = 0.648, t_m-t_s = 0.240). This result is similar to previous reports in other conifers (Kaya et al. 2006; Bower and Aitken 2007; Korshykov et al. 2016) but inconsistent with the results of nearly no inbreeding (t_m ≥ 1) in other Masson pine seed production populations (Zhang et al. 2008; Tan 2011; Feng et al. 2017). We inferred that all those studies derived from seedlings rather than seeds were unable to detect the proportion of selfed zygotes killed by recessive lethal genes during the stage of embryo development and germination (Kärkkäinen and Savolainen 1993); thus, the inbreeding level of Masson pine seed production populations is probably underestimated. Another isozyme result of open-pollinated seeds from a Masson pine seed orchard displayed a relatively low outcrossing rate (t_m = 0.792)(Lai and Wang 1997), indirectly supporting our speculation.

If inbreeding had a depression effect on seed development and germination, the seed mass and germination rate should be correlated (at least partially) with mating system parameters (i.e., inbreeding or outcrossing rate). As expected, the t_m and t_s of the sprout group were obviously higher than those of the seed group (Table 1). In turn, the mating among relatives of sprouts was slightly lower than that of seeds. This implied that partially inbred seeds may fail to germinate and thus be excluded from sprouts, which would explain the increase in the outcrossing rates of sprouts. The seeds group means all seeds with germinating and nongerminating capacity, and without doubt, the low outcrossing rate of seeds (compared with sprouts) was mainly caused by the latter. In other words, ID eliminates some inbred offspring from the germination stage.

Interestingly, regression analysis showed that the TSW was significantly affected by t_m and t_s, while the GR was mainly affected by t_m-t_s and t_s, not by t_m (Fig. 2). This implied that the ID of Masson pine was present not only during seed development but also during the germination phase. Moreover, the TSW seems to be more affected by self-fertilization than biparental inbreeding, while the GR is more influenced by the latter. One reason for this result is likely that some self-fertilized seeds, although relatively light in weight, still have the ability to germinate, which partly masked the influence of selfing (1-t_m) on the germination rate. These germinated selfing seeds may be due to weakly deleterious mutations and are very difficult to purge at the germination stage (Husband and Schemske 1996). Selfing seeds with equal or even higher germination ability relative to outcrossing seeds have been reported in some species, and approximately 50% (31 of 62) of species in Pinaceae have equal germination ability between inbred and outcross seeds (Baskin and Baskin 2015). The estimated percentage of ID on TSW due to selfing (26.3%) was larger than that of GR due to biparental inbreeding (16.4%), indicating that ID during seed development is more severe than that in the germination stage. This result is similar to previous results in other conifers studies (Husband and Schemske 1996; Mullin et al. 2019; Ahlinder et al. 2021). It should be noted that the real ID in TSW is probably higher than our estimate because some selfed but nondeveloped embryos cannot be genotyped (Salzer and Gugerli 2012).

Implications for seed production population management

In this study, mating system analysis of Masson pine seed tree stands revealed significant variation in three seed quality traits (TSW, GR, and GP) among seed trees, and the variation in TSW and GR was remarkably attributed to the inbreeding effect. The ID on TSW and GR of Masson pine is so unignorable that more attention should be given to the inbreeding statuses of the Masson pine seed production populations. Supplementary pollination during the reproductive season of Masson pine seed production populations is necessary to ensure a sufficient yield of noninbred seeds.

Funding

This work was supported by the National Natural Science Foundation of China (No. 32160381; No. 31400575) and the Natural Science Foundation of Guangxi (No. 2018GXNSFBA281110). We thank Jin-pei Ye and other staff members from Tianhongling State-Owned Forest Farm, Cangwu, Guangxi, for assistance in seeds collection. We also thank anonymous reviewers and editors for their helpful suggestions and comments.

Conflicts of interest

The authors declare that they have no conflict of interest.

Ethics approval

This article does not contain any studies involving animals or human participants performed by any of the authors.

Consent for publication (include appropriate statements)

The authors consent for publication.

Availability of data and material (data transparency)

Unavailable.

Code availability

Not applicable.

Authors' contributions

Wei Wei wrote the first manuscript. Mei-Xi Chen and Xian-Qin Li performed the experiments. Wei-Xin Jiang and Tian-Dao Bai revised and edited the manuscript. Wei-Xin Jiang and Tian-Dao Bai received and supervised the research project.

Aguiar BI, Freitas ML, Zannato AS, et al (2020) The effects of pollen dispersal and mating pattern on inbreeding depression and hybrid vigor in Balfourodendron riedelianum (Engl.) Engl.(Rutaceae). Conservation Genetics 21:305–317
Ahlinder J, Giles BE, García-Gil MR (2021) Life stage-specific inbreeding depression in long-lived Pinaceae species depends on population connectivity. Scientific Reports 11:8834
Ai C, Xu LA, Lai H, et al (2006) Genetic diversity and paternity analysis of a seed orchard in Pinus massoniana. Scientia Silvae Sinicae 42:146–150
Andersen US, Córdova JP, Nielsen UB, Kollmann J (2008) Provenance variation in germination and seedling growth of Abies guatemalensis Rehder. Forest Ecology and Management 255:1831–1840
Bai T (2013) Construction of second generation breeding population from open-pollinated progeny tests of Pinus massoniana seed orchard. PhD Thesis, Nanjing Forestry University
Bai T-D, Chen M-X, Ye J-P, et al (2021) Similar genetic diversity but increased differentiation revealed among a 58-year-old Pinus massoniana seed-tree stand and its progenies generated at different ages. Eur J Forest Res 140:649–656. https://doi.org/10.1007/s10342-021-01353-4
Baskin JM, Baskin CC (2015) Inbreeding depression and the cost of inbreeding on seed germination. Seed Science Research 25:355–385
Bower AD, Aitken SN (2007) Mating system and inbreeding depression in whitebark pine (Pinus albicaulis Engelm.). Tree Genetics & Genomes 3:379–388
Brown AH (1990) Genetic characterization of plant mating systems. In: Plant Population Genetics, Breeding, & Genetic Resources. Publisher: Sinauer Associates Inc., pp 145–159
Callejas-Díaz M, Chambel MR, San-Martín-Lorén J, et al (2022) The role of maternal age, growth, and environment in shaping offspring performance in an aerial conifer seed bank. American Journal of Botany 109:366–376
Calvo L, Hernández V, Valbuena L, Taboada A (2016) Provenance and seed mass determine seed tolerance to high temperatures associated to forest fires in Pinus pinaster. Annals of Forest Science 73:381–391
Castilleja Sánchez P, Delgado Valerio P, Sáenz-Romero C, Herrerías Diego Y (2016) Reproductive success and inbreeding differ in fragmented populations of Pinus rzedowskii and Pinus ayacahuite var. veitchii, two endemic Mexican pines under threat. Forests 7:178
Duminil J, Abessolo DTM, Bourobou DN, et al (2016) High selfing rate, limited pollen dispersal and inbreeding depression in the emblematic African rain forest tree Baillonella toxisperma – Management implications. Forest Ecology and Management 379:20–29. https://doi.org/10.1016/j.foreco.2016.08.003
Feng Y, Yang Z, Jia J, et al (2017) Temporal variation of mating system in a seed orchard of Pinus massoniana. Journal of Northeast Forestry University 45:1–4,11
Ganatsas P, Tsakaldimi M, Thanos C (2008) Seed and cone diversity and seed germination of Pinus pinea in Strofylia Site of the Natura 2000 Network. Biodiversity and Conservation 17:2427–2439
Gomaa NH, Picó FX (2011) Seed germination, seedling traits, and seed bank of the tree Moringa peregrina (Moringaceae) in a hyper-arid environment. American Journal of Botany 98:1024–1030
Gonzaga J, Manoel R, Sousa A, et al (2016) Pollen contamination and nonrandom mating in a Dehnh seedling seed orchard. Silvae Genetica 65:1–11
Griffin AR, Potts BM, Vaillancourt RE, Bell JC (2019) Life cycle expression of inbreeding depression in Eucalyptus regnans and inter-generational stability of its mixed mating system. Annals of Botany 124:179–187
Hirayama K, Ishida K, Tomaru N (2005) Effects of pollen shortage and self-pollination on seed production of an endangered tree, Magnolia stellata. Annals of Botany 95:1009–1015
Husband BC, Schemske DW (1996) Evolution of the magnitude and timing of inbreeding depression in plants. Evolution 50:54–70
Kärkkäinen K, Savolainen O (1993) The degree of early inbreeding depression determines the selfing rate at the seed stage: model and results from Pinus sylvestris (Scots pine). Heredity 71:160–166
Kaya N, Isik K, Adams W (2006) Mating system and pollen contamination in a Pinus brutia seed orchard. New Forests 31:409–416
Korshykov I, Kalafat L, Vynogradova O, Podgornyi D (2016) Genetic variability of maternal plants and embryos of their seeds in the populations of Pinus kochiana Klotzsch ex Koch in Crimea. Cytology and Genetics 50:110–115
Kuang M, Yang W, Xu H, et al (2010) A rapid method of DNA extraction from single cotton seed. Molecular Plant Breeding 8:827–831
Lai H, Wang M (1997) Research on mating systems in man-made populations of Masson pine. Scientia Silvae Sinicae 33:219–224
Loha A, Tigabu M, Teketay D, et al (2006) Provenance variation in seed morphometric traits, germination, and seedling growth of Cordia africana Lam. New forests 32:71–86
Mamo N, Mihretu M, Fekadu M, et al (2006) Variation in seed and germination characteristics among Juniperus procera populations in Ethiopia. Forest Ecology and Management 225:320–327
Mitton J (1992) The dynamic mating systems of conifers. New Forests 6:197–216
Moraes MA, Kubota TY, Rossini BC, et al (2018) Long-distance pollen and seed dispersal and inbreeding depression in Hymenaea stigonocarpa (Fabaceae: Caesalpinioideae) in the Brazilian savannah. Ecology and Evolution 8:7800–7816
Mullin TJ, Persson T, Abrahamsson S, Andersson Gull B (2019) Effects of inbreeding depression on seed production in Scots pine (Pinus sylvestris). Canadian Journal of Forest Research 49:854–860
Muñoz MC, Schaefer HM, Böhning-Gaese K, Schleuning M (2017) Importance of animal and plant traits for fruit removal and seedling recruitment in a tropical forest. Oikos 126:823–832
Muñoz-Gutiérrez L, Vargas-Hernández JJ, López-Upton J, et al (2019) Variation in reproductive phenology in a Pinus patula seed orchard and risk of genetic contamination from nearby natural stands. New Forests 50:1027–1041
Nakanishi A, Yoshimaru H, Tomaru N, et al (2015) Inbreeding depression at the sapling stage and its genetic consequences in a population of the outcrossing dominant tree species, Castanopsis sieboldii. Tree Genetics & Genomes 11:1–10
Ni ZX, Bai T, Cai H, et al (2015) The transferability of Pinus massoniana SSR in other Pinus species. Molecular Plant Breeding 13:2811–2817
Nickolas H, Harrison PA, Tilyard P, et al (2019) Inbreeding depression and differential maladaptation shape the fitness trajectory of two co-occurring Eucalyptus species. Annals of Forest Science 76:1–13
Oliver PAT, Borja MEL (2010) Seed mass variation, germination time and seedling performance in a population of Pinus nigra subsp. salzamannii. Forest Systems 19:344–353
Pringle EG, Alvarez-Loayza P, Terborgh J (2007) Seed characteristics and susceptibility to pathogen attack in tree seeds of the Peruvian Amazon. Plant Ecology 193:211–222
Prochazkova Z (2009) Quality assessment methods for Picea abies seeds. Dendrobiology 61:111–115
Pupin S, Sebbenn AM, Cambuim J, et al (2019) Effects of pollen contamination and non-random mating on inbreeding and outbreeding depression in a seedling seed orchard of Eucalyptus urophylla. Forest Ecology and Management 437:272–281
R Core Team (2020) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria
Ritland K (2002) Extensions of models for the estimation of mating systems using n independent loci. Heredity 88:221–228
Ritz C, Baty F, Streibig JC, Gerhard D (2015) Dose-Response Analysis Using R. PLOS ONE 10:e0146021
Sabin TE, Stafford SG, others (1990) Assessing the need for transformation of response variables. Forest Research Laboratory, Oregon State University
Salzer K, Gugerli F (2012) Reduced fitness at early life stages in peripheral versus core populations of Swiss stone pine (Pinus cembra) is not reflected by levels of inbreeding in seed families. Alpine Botany 122:75–85
Stacy EA (2001) Cross-fertility in two tropical tree species: evidence of inbreeding depression within populations and genetic divergence among populations. American Journal of Botany 88:1041–1051
Suárez-Vidal E, Sampedro L, Zas R (2017) Is the benefit of larger seed provisioning on seedling performance greater under abiotic stress? Environmental and Experimental Botany 134:45–53
Takeuchi Y, Kikuchi S, Diway B (2020) Albinism and inbreeding depression in seedlings of the tropical tree, Shorea laxa. Journal of Forest Research 25:413–419
Tan X (2011) study on the selection of second generation breeding parents and the mating system of seed orchard in Pinus massoniana. PhD Thesis, Chinese Academy of Forestry
Tumpa K, Vidaković A, Drvodelić D, et al (2021) The effect of seed size on germination and seedling growth in sweet chestnut (Castanea sativa Mill.). Forests 12:858
Williams CG, Savolainen O (1996) Inbreeding depression in conifers: implications for breeding strategy. Forest Science 42:102–117
Xu J, Wang Z, Chen Y, Qiu J (2004) An analysis of genetic parameters, characters of seed and cone, and cone yield of clone grown in a seed orchard for Pinus massoniana. Scientia Silvae Sinicae 40:201–205
Zhang W, Gong J, Ji K (2008) Genetic diversity for seedling orchard of Masson’s pine. Molecular Plant Breeding 6:717–723

No competing interests reported.

SupplementalmaterialII.pdf

Download PDF

Version 1

posted

You are reading this latest preprint version

How does population outcrossing rate influence seed quality? Evidence from a 58-year-old seed tree stand of Pinus massoniana

Status:

Version 1

Abstract

Figures

Introduction

Material And Methods

Plant material

Seed quality measurement

DNA extraction and genotyping

Data analysis

Results

Seed quality variation

Mating system

Discussion

Variation in seed quality among seed trees

Mating system and inbreeding depression

Implications for seed production population management

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1