Table1_Multivariate analysis and genetic dissection of staygreen and stem reserve mobilisation under combined drought and heat stress in wheat (Triticum aestivum L.).docx

Introduction: Abiotic stresses significantly reduce crop yield by adversely affecting many physio-biochemical processes. Several physiological traits have been targeted and improved for yield enhancement in limiting environmental conditions. Amongst them, staygreen and stem reserve mobilisation are two important mutually exclusive traits contributing to grain filling under drought and heat stress in wheat. Henceforth, the present study was carried out to identify the QTLs governing these traits and to identify the superiors’ lines through multi-trait genotype-ideotype distance index (MGIDI)Methods: A mapping population consisting of 166 recombinant inbred lines (RILs) developed from a cross between HD3086 and HI1500 was utilized in this study. The experiment was laid down in alpha lattice design in four environmental conditions viz. Control, drought, heat and combined stress (heat and drought). Genotyping of parents and RILs was carried out with 35 K Axiom® array (Wheat breeder array).Results and Discussion: Medium to high heritability with a moderate to high correlation between traits was observed. Principal component analysis (PCA) was performed to derive latent variables in the original set of traits and the relationship of these traits with latent variables.From this study, 14 QTLs were identified, out of which 11, 2, and 1 for soil plant analysis development (SPAD) value, leaf senescence rate (LSR), and stem reserve mobilisation efficiency (SRE) respectively. Quantitative trait loci (QTLs) for SPAD value harbored various genes like Dirigent protein 6-like, Protein FATTY ACID EXPORT 3, glucan synthase-3 and Ubiquitin carboxyl-terminal hydrolase, whereas QTLs for LSR were found to contain various genes like aspartyl protease family protein, potassium transporter, inositol-tetrakisphosphate 1-kinase, and DNA polymerase epsilon subunit D-like. Furthermore, the chromosomal region for SRE was found to be associated with serine-threonine protein kinase. Serine-threonine protein kinases are involved in many signaling networks such as ABA mediated ROS signaling and acclimation to environmental stimuli. After the validation of QTLs in multilocation trials, these QTLs can be used for marker-assisted selection (MAS) in breeding programs.

引言：非生物胁迫显著降低作物产量，通过不利影响众多生理生化过程来实现。为在限制性环境条件下提高产量，已针对多种生理特性进行靶向和改良。其中，耐旱性和茎储备动员是两个相互排斥的重要特性，它们在小麦遭受干旱和热胁迫时对籽粒充实度作出贡献。因此，本研究旨在识别调控这些特性的数量性状位点（QTLs），并通过多特性基因型-理想型距离指数（MGIDI）识别优质品系。方法：本研究利用由HD3086与HI1500杂交产生的166个重组自交系（RILs）构建的遗传图谱。实验在四种环境条件下进行，即对照、干旱、热和复合胁迫（热和干旱）。采用35K Axiom®阵列（小麦育种阵列）对亲本和RILs进行基因分型。结果与讨论：观察到中等至高遗传力以及性状间中等至高的相关性。通过主成分分析（PCA）从原始性状集中推导出潜在变量，并分析了这些性状与潜在变量之间的关系。本研究共鉴定出14个QTLs，其中11个与土壤植物分析发展（SPAD）值相关，2个与叶片衰老速率（LSR）相关，1个与茎储备动员效率（SRE）相关。SPAD值的QTLs包含诸如Dirigent蛋白6样、蛋白质FATTY ACID EXPORT 3、葡萄糖合酶-3和泛素羧基端水解酶等基因，而LSR的QTLs被发现包含天冬氨酸蛋白酶家族蛋白、钾转运蛋白、肌醇四磷酸1-激酶和DNA聚合酶epsilon亚基D样等基因。此外，SRE的染色体区域与丝氨酸-苏氨酸蛋白激酶相关。丝氨酸-苏氨酸蛋白激酶参与多种信号网络，如ABA介导的活性氧（ROS）信号和适应环境刺激。在多地点试验中对QTLs进行验证后，这些QTLs可用于育种计划中的标记辅助选择（MAS）。