Integrated multi-omics analysis reveals how PdMYB44 enhances drought tolerance in Pugionium dolabratum by activating the ascorbate-glutathione cycle.

BACKGROUND AND AIMS: Oxidative damage caused by drought stress is a key factor limiting crop survival and distribution. The desert plant Pugionium dolabratum exhibits extreme drought tolerance, but its intrinsic antioxidant regulatory mechanism remains unclear.

METHODS

In this study, a progressive soil drought treatment was used systematically to evaluate the growth status of P. dolabratum seedlings and the dynamic response of the ascorbate-glutathione (AsA-GSH) cycle.

KEY

RESULTS

Integrated transcriptomic and proteomic analyses identified a set of genes significantly and concordantly regulated at both transcriptional and translational levels under drought stress. From these, PdMYB44, a gene encoding a MYB44 transcription factor with conserved roles in stress responses, was prioritized for functional analysis. Overexpression of PdMYB44 in Arabidopsis conferred enhanced drought tolerance in comparison to the wild-type plants, evidenced by a 12.50 % increase in seed germination rate, elevated leaf relative water content and proline content, coordinated decreases in stomatal conductance and transpiration, and enhanced ROS scavenging capacity via the AsA-GSH cycle, as indicated by increased AsA and GSH pools (by 69.92 and 19.13 %, respectively) and elevated ascorbate peroxidase and glutathione reductase activities. Notably, in non-stress conditions, PdMYB44 overexpression promoted early flowering. To explore the molecular mechanism, we performed yeast two-hybrid assays, which revealed a direct interaction between PdMYB44 and glutathione S-transferase PdGST.

CONCLUSIONS

This study reveals that a direct interaction between PdMYB44 and PdGST enhances the AsA-GSH cycle efficiency, thereby promoting reactive oxygen species scavenging and significantly improving plant drought tolerance. To our knowledge, this is the first report to unveil the direct 'MYB44-GST' regulatory module in a desert plant, providing an important theoretical basis and a genetic resource for improving crop stress resistance.