Transcriptome Analysis Identifies OsWRKY26 as a Key Regulator for Cold Tolerance at the Seedling Stage in Rice

TL;DR

This study identifies OsWRKY26 as a key gene that helps rice seedlings tolerate cold stress, offering insights into rice adaptation and breeding for cold environments.

Contribution

The study reveals OsWRKY26 as a novel regulator of cold tolerance in rice and explores its evolutionary role in domestication.

Findings

OsWRKY26 is significantly upregulated under cold stress and localized in the nucleus.

Transgenic experiments show OsWRKY26 enhances seedling cold tolerance in rice.

OsWRKY26 and OsMYB2 diverged in wild rice and were selected during domestication in cold regions.

Abstract

Cold stress poses a major threat to rice productivity and grain quality. WRKY transcription factors, one of the largest plant-specific gene families, play crucial roles in plant responses to abiotic stress. However, their functions in cold responses and the evolutionary mechanisms underlying cold adaptation during the long-term domestication of cultivated rice remain poorly understood. Here, we identified OsWRKY26 as an important regulator of cold adaptation in japonica subspecies through transcriptome sequencing (RNA-seq). Subcellular localization analysis showed that the OsWRKY26 protein is localized to the nucleus under both normal and cold-stress conditions. Expression analysis indicated that OsWRKY26 is significantly upregulated at low temperature. Moreover, transgenic validation and measurements of multiple physiological traits demonstrated that OsWRKY26 positively regulates seedling cold tolerance in rice. Evolutionary analyses of OsWRKY26 and OsMYB2, a previously reported positive regulator of rice cold tolerance, suggested that these two genes diverged in wild rice and subsequently experienced directional selection in temperate japonica cultivated in high-altitude and high-latitude regions. Together, these findings provide a theoretical foundation for dissecting cold-tolerance mechanisms in rice, as well as promising genetic resources for molecular breeding in low-temperature environments.

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