Comparative analysis of physiological, agronomic and transcriptional responses to drought stress in wheat local varieties from Mongolia and Northern China.

Drought is one of the major abiotic stresses that threaten wheat production worldwide, especially in the Mongolian Plateau and adjacent regions. This study aims to find local wheat varieties with high yields and drought resistance at various developmental stages based on agronomic traits and drought resistance indices analysis and explore the underlining molecular mechanisms by transcriptome analysis. Our results revealed that drought stress started at the seedling stage has a greater impact on crop yields. Four types of drought responses were found among the tested varieties. Type 1 and type 2 show low tolerance to drought stress despite high or low yield in control condition, type 3 exhibits high yield under control condition but dropped significantly after drought, and type 4 displays relatively high and stable yields under control and drought conditions. Transcriptome analysis performed with the representative varieties of the four types revealed GO terms and KEGG pathways enriched among drought-triggered differential expressed genes (DEGs). A network containing 18 modules was constructed using weighted gene co-expression analysis (WGCNA). Ten modules were significantly correlated to yield by module-trait correlation, and 3 modules showed Darkhan 144 specific gene expression patterns. C2H2 zinc finger factor-recognized motifs were identified from the promoters of genes in these modules. qRT-PCR confirmed several key DEGs with specific expression patterns and physiological measurements validated the relatively low oxidative damage and high antioxidant capacity in the drought tolerant variety Dankhan 144. These findings provide an important basis for local agriculture and breeding of drought-tolerant high yield wheat varieties.