Autophagy Related Gene <i>CaATG6</i> Positively Regulates Heat Stress in Pepper

ABSTRACT High temperatures can harm the growth and development of plants. Autophagy, as a conserved degradation system in eukaryotic cells, is essential for plant response to stress. However, the role of CaATG6 under heat stress is unclear. In this research, we discovered that CaATG6 contains a conserved APG6 domain, and CaATG6 had a closer phylogenetic relationship to other Solanaceae homologues. Silencing of CaATG6 reduced pepper heat tolerance, while overexpression of CaATG6 in Arabidopsis enhanced the heat tolerance. CaATG6 can improve heat tolerance in plants by upregulating the expression of CaHsfA2 , CaHSP16.4 , CaHSP25.9 and CaHSP70.1 , as well as enhancing autophagy levels. Moreover, we discovered that CaATG6 interacts with CaSKIP34 , an F‐box protein of the E3 ubiquitin ligase SCF complex. Interestingly, both silencing and overexpression of CaSKIP34 reduced heat tolerance in plants. We also observed that the protein level of CaSKIP34 decreased after heat stress treatment, but this reduction was inhibited by autophagy and proteasome inhibitors. Therefore, we hypothesise that CaATG6 may regulate plant heat tolerance by modulating CaSKIP34 stability. This study offers fresh perspectives on the role of the autophagy core gene CaATG6 in thermotolerance in pepper.