Synergistic Interaction Between PbbZIP88 and PbSRK2E Enhances Drought Resistance in Pear Through Regulation of PbATL18 Expression and Stomatal Closure.

ABSTRACT

Drought poses significant challenges to agricultural production, ecological stability and global food security. While wild pear trees exhibit strong drought resistance, cultivated varieties show weaker drought tolerance. This study aims to elucidate the molecular mechanisms underlying pear trees' response to drought stress. We identified a drought resistance-related transcription factor, PbbZIP88, which binds to and activates the expression of the drought-responsive gene PbATL18. Overexpression of PbbZIP88 in Arabidopsis and pear seedlings resulted in enhanced drought resistance and significantly improved physiological parameters under drought stress. We discovered that PbbZIP88 interacts with the key protein PbSRK2E in the ABA signalling pathway. This interaction enhances PbbZIP88's ability to activate PbATL18 expression, leading to higher levels of PbATL18. Furthermore, the PbbZIP88 and PbSRK2E interaction accelerates the regulation of stomatal closure under ABA treatment conditions, reducing water loss more effectively. Experimental evidence showed that silencing PbbZIP88 and PbSRK2E genes significantly decreased drought resistance in pear seedlings. In conclusion, this study reveals the synergistic role of PbbZIP88 and PbSRK2E in enhancing drought resistance in pear trees, particularly in the upregulation of PbATL18 expression, and the accelerated promotion of stomatal closure. These findings provide new candidate genes for breeding drought-resistant varieties and offer a theoretical foundation and technical support for achieving sustainable agriculture.