Cloning and High Temperature Tolerance Analysis of the Thermal Response Related Gene KcRCB in Karelinia caspia (Pall.) Less

Wenlong Li^*Wanyi HuangYanhai ZhaoGuoqiang LiShuguang LiYanqin Wan^*

• Tarim University, Aral, China

The REGULATOR OF CHLOROPLAST BIOGENESIS (RCB) is a novel protein component in plant temperature signaling that functions by synergizing with HEMERA (HMR) to initiate thermomorphogenesis by stabilizing PHYTOCHROME INTERACTING TRANSCRIPTION FACTOR 4 (PIF4) during the day. In this study, we successfully cloned the heat-responsive gene KcRCB from Karelinia caspia, a desert-adapted plant species. KcRCB transcript levels were significantly elevated when the plants were exposed to high temperatures. Furthermore, KcRCB demonstrated differential expression in the Karelinia caspia roots, stems, and leaves, with optimal expression in the leaves. Subsequently, KcRCB transgene was overexpressed in Arabidopsis thaliana and cotton plants to characterize its thermomorphogenesis effects. In comparison with the wild-type Arabidopsis thaliana plants, KcRCB-overexpressing Arabidopsis thaliana plants exhibited reduced incidence of leaf damage and enhanced capacity to withstand elevated temperatures. KcRCB-overexpressing cotton plants subjected to elevated temperatures also exhibited reduced leaf damage. Physiological assays demonstrated that KcRCB expression enhances plant resilience to high-temperature stress by maintaining cell membrane stability and reducing the accumulation of reactive oxygen species (ROS). Moreover, we observed increased stomatal density and opening in the leaves of the KcRCB overexpressing lines compared to the control group when exposed to high temperatures. Subcellular localization experiments showed that KcRCB was localized to the stomatal guard cell membranes. This suggested that KcRCB protects plant cells from high-temperature-related damage by regulating stomatal openness, increasing the transpiration rate, and improving the efficiency of heat dissipation, thereby. These findings enhance the understanding of the mechanisms underlying high-temperature tolerance in the desert plant species. Specifically, this study expands our understanding regarding the biological roles of KcRCB and the molecular regulatory networks underlying heat stress responses in Karelinia caspia.