Potential role of the regulatory miR1119-MYC2 module in wheat (Triticum aestivum L.) drought tolerance

MicroRNA (miRNA)-target gene modules are essential components of plants' abiotic stress signalling pathways Little is known about the drought-responsive miRNA-target modules in wheat, but systems biology approaches have enabled the prediction of these regulatory modules and systematic study of their roles in responses to abiotic stresses. Using such an approach, we sought miRNA-target module(s) that may be differentially expressed under drought and non-stressed conditions by mining Expressed Sequence Tag (EST) libraries of wheat roots and identified a strong candidate (miR1119-MYC2). We then assessed molecular and physiochemical differences between two wheat genotypes with contrasting drought tolerance in a controlled drought experiment and assessed possible relationships between their tolerance and evaluated traits. We found that the miR1119-MYC2 module significantly responds to drought stress in wheat roots. It is differentially expressed between the contrasting wheat genotypes and under drought versus non-stressed conditions. We also found significant associations between the module's expression profiles and ABA hormone content, water relations, photosynthetic activities, H2O2 levels, plasma membrane damage, and antioxidant enzyme activities in wheat. Collectively, our results suggest that a regulatory module consisting of miR1119 and MYC2 may play an important role in wheat's drought tolerance.

Automated summary

MicroRNA (miRNA)-target gene modules are crucial for plants' response to abiotic stress. In this study, we used a systems biology approach to predict and study the role of a drought-responsive miRNA-target module (miR1119-MYC2) in wheat. We identified differential expression of this module between wheat genotypes with contrasting drought tolerance and under drought versus non-stressed conditions. Furthermore, we found significant associations between the module's expression profiles and various physiological and molecular traits related to drought tolerance in wheat. These findings suggest the importance of miR1119-MYC2 module in wheat's adaptation to drought stress.