This study bred 2 new cultivated potato varieties, Q9 and X65, with high-yielding and high-resistance properties in Qinghai, China. We have a tendency to in the main targeted on the constitution traits and correlate genetic data within the roots, shoots, and leaves of Q9 and X65 underneath N deficiency and sufficiency. RNA-Seq associate degree alysis is an economical technique to check genome-wide changes in factor transcription and screen existing factor resources in response to totally different N concentrations (Tiwari et al. 2020; Zhang et al. 2020; Ueda et al. 2020; Sultana et al. 2020). Previous studies known N-responsive genes by 2 approaches: one involves reducing and/or depletion of N within the growth media, work low-N stress (N starvation). The opposite is achieved by resupplying traditional N to seedlings mature in media with no or very little N, targeted on NUE. Key genes functioning in plant survival were concerned in response to N starvation, as well as those concerned within the overall stress response, pigment synthesis, and N assimilation.
Furthermore, N absorption and assimilation genes were upregulated throughout N supplementation (Balazadeh et al. 2014; Sun et al. 2017; Yang et al. 2015; Chandran et al. 2016). To enhance NUE, it's essential to grasp the plant response to N treatments, particularly to N limitation at each the physiological and transcriptomic levels. During this study, the candidate genes were selected supported the previous studies, which can have a potential role in rising NUE (Tiwari et al. 2020; Tiwari et al. 2020; Zhang et al. 2020).
Multiple responsive mechanisms to N treatment are known in crop plants. Among these, photosynthesis, as well as PS I and PS II, N metabolism, transcription factors, and secretion sign, were screened because the main mechanisms of N treatment and tolerance (Subudhi et al. 2020; Ueda et al. 2020; Ma et al. 2021; Wang et al. 2021; Chen et al. 2020; Liu et al.2021). However, our study integrated all hub genes related to traits that occurred in the roots, shoots, and leaves of potatoes (Figs. 2, 4, 5). We tend to first obtained the potato plant heights, chlorophyll contents, dry matter levels, and N accumulation contents (Fig. 1). Each potato cultivars square measure sensitive to N deficiency conditions. This ends up in a smaller plant height, lower leaf chlorophyll contents, and fewer dry matter weight and N accumulation, particularly in roots and shoots. These results square measure in accordance with those of a previous study (Tiwari et al. 2020; Zhang et al. 2020; Ueda et al. 2020; Sultana et al. 2020; Mu et al. 2017; Guo et al. 2020; Perchlik and Tegeder 2018). In plants, chemical action plays a decisive role in carbon fixation and biomass accumulation. In higher plants, the sunshine reaction of chemical action is accomplished by the two photosystems PS I and PS II. These two photosystems add series through the photosynthetic energy transport chain. They're concerned in the light-dependent reactions of carbon fixation (Gururani et al. 2015). In the present study, nineteen genes involved in the photosynthesis pathway were downregulated below N deficiency (Table 1, Fig. 5B and S2). All nineteen were enriched in the light-harvesting chlorophyll protein complex (LHC), such as Lhca/b1, Lhca/b 2, Lhca/b 3, Lhca/b 4, and Lhcb6, which bind to PS I and PS II. The results that N nutrition and NUE enhance the photosynthetic pathways. Besides, those genes also are enriched in GO terms "phosphate and containing compound metabolic process," "photosynthesis," "membrane," and "binding" (Fig. 3). All results show the interconnected relationship between photosynthesis and N metabolism.
Previous studies equipped potential roles of those N metabolism-associated genes, particularly transporters underneath N stress tolerance in potato (Tiwari et al. 2020; Afzal et al. 2016; Wang et al. 2012). DEGs happiness the NRT gene family were involved in nitrogen transport from the living thing to intracellular method. NRTs square measure liable for the absorption of nitrate from soil and translocation among completely different components of plants. They deliver nitrate where needed and square measure concerned in addressing adverse environmental conditions (Zhang et al. 2018).
Moreover, as per the previous report, the NRT family was found to be concerned in root growth, flowering time, and transcriptional regulation of multiple physiological processes, secretion and nitrate sign (Bouguyon et al. 2016; Teng et al. 2019; Zhang et al. 2019). The upregulated DEGs, the member of NIR and NRT gene families, increased crop nutrient uptake (Fang et al. 2016). We found several NRT gene families (Fig. 5C and 6, Table S4). Interestingly, the expression of NRT gene family members in N-deficient potato groups was upregulated in root and shoot. Besides, we tend to conjointly found that the aminoalkanoic acid, organic compound transporters, and basic principle transporters play key roles in N uptake and transformation from potato root to shoot, and lastly, to leaf (Table 1). The best enrichment score of those metabolic pathways in potato cultivars below N0 and N1 treatment indicated that multiple transcription differences strongly influenced the root, shoot, and leaf nitrogen metabolism.
Furthermore, the plant hormone Auxin is critical for plant growth and development processes. It plays its regulatory role primarily by inducing the expression of early auxin response genes. The source of auxin or auxin transport discovered a task for growth regulator in regulation N remobilization (Hu et al. 2020; Li et al. 2020). Using WGCNA and co-expression methodology, we tend to known many DEGs involved in Auxin-induced and Auxin-regulated (Figs. 4 and 6). We've got obtained several DEGs associated with the photosynthetic pathway and Nitrogen metabolism pathway. Finally, to identify the expression level and patterns, we selected fourteen DEGs from the 116, which were extremely co-expressed and connected with the traits. The NRTs, Auxin-induced, Auxin-regulated, NRT1.1, chloroplast pigment-binding, chlorophyll a-b binding, ATP synthase, wall-associated kinase, and NADPH genes kept consistent between RNA-Seq and qPCR detection. The candidate genes could be used for genetic manipulation for increasing NUE in potatoes via transgenic or CRISPR/Cas9 or base-editing technologies (Tiwari et al. 2020). We speculate that exploring the molecular functions of these genes requires further experimental verification.
This study has several limitations: (i) This study did not conduct multiple growth stages rather one growth stage. (ii) The genetic correlation among multiple crop plants could not be conducted in this present study. (iii) The cultivar-specific expression pattern of genes and corresponding mutants’ performance throughout N deficiency were not presented in this present study. (iv) The newest potato database DMv 11.6, was not used in this present study which might be useful for distinguishing the isoforms. Therefore, we tend to shall use these in our future study of this subject with extended experiments.