Correspondence: dwwang@henau.edu.cn (D. W.)

Drought stress severely limits worldwide wheat productivity. Consequently, studying and improving wheat drought tolerance and water use efficiency (WUE) are an urgent need for securing sustainable wheat production. However, drought tolerance and WUE are complex quantitative traits, which are difficult to dissect especially in polyploid wheat. In previous studies, we found that the wheat gene TaXTH13, encoding xyloglucan endotransglucosylase/ hydrolase, was induced by water stress, and could enhance drought tolerance when overexpressed in wheat.

Further research revealed that TaXTH13 improves the drought tolerance of wheat by promoting ABA synthesis, reducing stomatal opening and enhancing reactive oxygen species (ROS) scavenging. Interestingly, we found that TaXTH13-B has two haplotypes, namely Hap1TaXTH13-B and Hap2TaXTH13-B. The promoter activity of Hap2TaXTH13-B was significantly stronger than that of Hap1TaXTH13-B, which correlated with higher drought tolerance index values exhibited by the cultivars carrying Hap2TaXTH13-B.

Altogether, our results suggest that TaXTH13 plays an important role in shaping wheat drought tolerance via its impact on ABA biosynthesis and signaling and that marker-assisted selection of Hap2TaXTH13-B is valuable for breeding more drought tolerant wheat cultivars in the future.