OsIAA7 enhances heat stress tolerance by inhibiting the activity of OsARF6 in rice

Abstract

Heat stress (HS) severely affects the growth and yield of rice, necessitating a clear understanding of the molecular mechanisms underlying HS tolerance. In this study, we report that the Aux/IAA family gene, OsIAA7, whose expression is induced by HS and positively regulates HS tolerance in rice (Oryza sativa L.). The osiaa7 mutant exhibits reduced HS tolerance, whereas overexpression of OsIAA7 enhances it. Our findings suggest that OsIAA7 contributes to HS tolerance by reducing hydrogen peroxide accumulation and cell death. Physiological analysis indicates that OsIAA7 influences the levels of malondialdehyde, catalase, and chlorophyll A concentration in plants under HS conditions. RNA-seq analysis suggests that OsIAA7 modulates the expression of heat-responsive genes, contributing to HS tolerance. Further, biochemical analyses demonstrate a physical interaction between OsIAA7 and OsARF6, with OsIAA7 inhibiting the activity of OsARF6. RT-qPCR results support the notion that the positive regulatory factor OsIAA7 and the negative regulatory factor OsARF6 control HS tolerance by regulating the transcript levels of OsTT1 and OsTT3.1. Together, our results reveal the role of OsIAA7 in controlling HS tolerance through the modulation of physiological processes and the inhibition of OsARF6 activity, suggesting that some Aux/IAA family genes play a role in heat tolerance in rice.

Keywords: Auxin signaling pathway; Heat stress; OsARF6; OsIAA7; Rice.