Genetic variants of OsWRKY70 modulate ROS levels to improve rice stress adaptation

Abstract

OsWRKY70 modulates ROS levels in rice to enhance tolerance to cold and salt stress. OsWRKY70^HapI reduces ROS and improves cold and salt tolerance, while OsWRKY70^HapII regulates ROS to increase salt tolerance and cold sensitivity, making OsWRKY70 a key target for improving rice stress resilience. Reactive oxygen species are essential in plant responses to abiotic stresses like drought, salinity, and extreme temperatures. In rice, the transcription factor OsWRKY70 plays a pivotal role in regulating ROS levels to enhance stress tolerance. This study examines two haplotypes of OsWRKY70, OsWRKY70^HapI and OsWRKY70^HapII, and their effects on rice resilience to cold and salt stress. Overexpression of OsWRKY70^HapI resulted in lower ROS accumulation, significantly improving cold tolerance by upregulating the antioxidant gene OsMYB4 and maintaining ion balance through OsMYB21 and OsAMTR1. In contrast, OsABA8ox1 led to higher ROS levels in OsWRKY70^HapII and increased sensitivity to cold stress, while still enhancing salt tolerance similar to OsWRKY70^HapI by regulating OsMYB21 and OsAMTR1. Haplotype analysis identified specific SNPs in OsWRKY70 that are critical for its transcriptional activity and stress response functions. Subcellular localization confirmed that OsWRKY70 operates as a nuclear transcription factor. These findings highlight the potential of OsWRKY70 haplotypes in genetic strategies to improve rice resilience to adverse environmental conditions by precisely modulating ROS and stress-responsive genes.