Physio-morphological and biochemical trait-based evaluation of Ethiopian and Chinese wheat germplasm for drought tolerance at the seedling stage

For Ethiopia’s wheat production, drought is a major natural disaster. Exploration of drought-resistant varieties from a bulk of wheat germplasm conserved in the gene bank is of paramount importance for breeding climate change-resilient modern cultivars. The present study was aimed at identifying the best performing drought-resistant genotypes under non-stress and polyethylene glycol simulated (PEG) stress conditions in a growth chamber. Forty diverse Ethiopian bread and durum wheat cultivars along with three Chinese bread wheat cultivars possessing strong drought resistance and susceptibility were evaluated. After acclimation with the natural environment, the seedlings were imposed to severe drought stress (20% PEG6000), and 15 seedling traits including photosynthetic and free proline were investigated. Our findings indicated that drought stress caused a profound decline in plant water consumption (83.0%), shoot fresh weight (64.9%), stomatal conductance (61.6%), root dry weight (55.2%), and other investigated traits except root to shoot length ratio and proline content which showed a significant increase under drought stress. A significant and positive correlation was found between photosynthetic pigments in both growth conditions. Proline exhibited a negative correlation with most of the investigated traits except root to shoot length ratio and all photosynthetic pigments which showed a positive and non-significant association. Our result also showed a wide range of genetic variation (CV) ranging from 3.23% to 47.3%; the highest in shoot dry weight (SDW) (47.3%) followed by proline content (44.63%) and root dry weight (36.03%). Based on multivariate principal component biplot analysis and average sum of ranks (ASR), G12, G16 and G25 were identified as the best drought tolerant and G6, G42, G4, G11, and G9 as bottom five sensitive. The potential of these genotypes offers further investigation at a molecular and cellular level to identify the novel gene associated with the stress response.

针对埃塞俄比亚小麦生产而言，干旱是一种主要的自然灾害。从基因库保存的大量小麦种质资源中发掘抗旱品种，对于培育适应气候变化的现代栽培品种至关重要。本研究旨在生长室环境下，探究非胁迫及聚乙二醇（Polyethylene glycol，PEG）模拟胁迫条件下的最优抗旱基因型。本试验共评估了40份多样化的埃塞俄比亚普通面包小麦与硬粒小麦品种，以及3份兼具强抗旱性或高抗旱敏感性的中国普通面包小麦品种。经自然环境驯化后，对幼苗施加重度干旱胁迫（20% PEG6000），并测定了包括光合性状与游离脯氨酸在内的15项幼苗相关性状。研究结果表明，干旱胁迫会使植株耗水量（降幅达83.0%）、地上部鲜重（降幅64.9%）、气孔导度（降幅61.6%）、根系干重（降幅55.2%）及其他多数测定性状出现显著下降；唯有根冠长度比与脯氨酸含量在干旱胁迫下呈现显著上升。两种生长条件下的光合色素间均存在显著正相关关系。脯氨酸与多数测定性状呈负相关，但与根冠长度比及所有光合色素呈正相关且关联不显著。本研究结果还显示，群体遗传变异系数（CV）的分布范围为3.23%至47.3%，其中地上部干重（SDW）的变异系数最高（47.3%），其次为脯氨酸含量（44.63%）与根系干重（36.03%）。基于多变量主成分双标图分析与平均秩和（ASR）法，本研究鉴定出G12、G16与G25为最优抗旱基因型，而G6、G42、G4、G11与G9为抗旱性最差的5个敏感基因型。这些基因型的应用潜力为后续在分子与细胞水平开展研究、发掘与胁迫响应相关的新基因提供了重要支撑。