Genome-wide identification of FCS-Like Zinc finger (FLZ) genes in four Solanaceae plant species and functional characterization of SlFLZ2 and SlFLZ18 in tomato under heat stress

Members of the FCS-Like Zinc finger proteins (FLZs) are involved in energy homeostasis and stress signaling in Arabidopsis thaliana, maize (Zea mays), and rice (Oryza sativa) by forming a complex with SnRK (sucrose non-fermenting 1 related protein kinase). Nevertheless, a comprehensive analysis of the FLZ gene family in Solanaceae species is absent. In this study, the structure, and evolutionary characteristics of FLZs were revealed in four economically important Solanaceae plant species. A total of 78 FLZs were identified in four Solanaceae species, including 19 in tomato (Solanum lycopersicum), 19 in pepper (Capsicum annuum), 18 in potato (S. tuberosum), and 22 in eggplant (S. melongena). The FLZs of Solanaceae species and the other three model plant species (Arabidopsis, rice, and maize) were classified into four classes. For the four Solanaceae species, 63 collinear gene pairs were identified. There were 26, 11 and 13 orthologous gene pairs between tomato and the other three model plants species. SnRKs are involved in abiotic stress responses in plant. Yeast two-hybrid assays showed that SlFLZ2 interacts with SlSnRK2.6, SlSnRK2.7 or SlSnRK2.8, and both SlFLZ8 and SlFLZ14 can interact with SlSnRK2.3. The expression of SlFLZ2 and SlFLZ18 increased following heat treatment and silencing of SlFLZ2 or SlFLZ18 impaired the heat stress tolerance, suggesting that these genes may positively regulate tolerance to heat stress in tomato. Taken together, these findings improve our current understanding of the evolution, structure, and function of FLZs in Solanaceae and provide framework for further exploration of the regulatory mechanisms of FLZ-mediated stress tolerance in Solanaceae crops.