Receptor-like kinases (RLKs) play vital roles in development, stress perception and signal transduction, acting as core components in abiotic stress responses in plants. As important regulators of plant adaptation to harsh environments, RLKs are particularly critical for extremophytes surviving extreme cold, drought, and high-UV stress. However, the RLK gene family in extremophytes, such as Orinus species distributed in Qinghai-Xizang (Tibet) Plateau (QTP), remains largely uncharacterized. Given the unique adaptation of Orinus to the extreme QTP habitat, investigating the RLK gene family is essential to uncover the molecular basis of its stress tolerance and high-altitude adaptation. Here, we performed a comprehensive genome-wide analysis of RLK genes in Orinus (ORLKs) to identify a total of 647 ORLK candidates classified into 52 subfamilies. Phylogenetic and synteny analyses revealed a close evolutionary relationship between Orinus and wheat (Triticum aestivum), with extensive collinearity detected among five core subfamilies. Moreover, the ORLKs exhibited an uneven chromosomal distribution, accompanied by tandem duplication events. To assess the potential function of these ORLKs, we compared the expression profiles between two species of Orinus (O. thoroldii and O. kokonoricus) and identified 120 differentially expressed ORLK genes (DEGs). Cis-acting element analysis of DEG promoters revealed a significant enrichment of hormone-responsive, stress-responsive and light-responsive elements, indicating the complexity of their regulatory networks. This study provides insights into the molecular mechanisms of adaptation to extreme environments in Orinus on QTP, revealing evolutionary innovations in RLKs that could inform strategies for engineering stress-tolerant crops, and our findings establish a functional genomic foundation for RLK-mediated signaling in extremophytes.
Fang et al. (Wed,) studied this question.