Genome-wide identification and analysis of the evolution and expression pattern of the HVA22 gene family in three wild species of tomatoes

Wild tomato germplasm is a valuable resource for improving biotic and abiotic stresses in tomato breeding. The HVA22 is widely present in eukaryotes and involved in growth and development as well as stress response, such as cold, salt, drought, and biotic stress. In the present study, we identified 45 HVA22 genes in three wild species of tomatoes. The phylogenetic relationships, gene localization to chromosomes, gene structure, gene collinearity, protein interactions, and cis-acting element prediction of all 45 HVA22 genes (14 in Solanum pennellii, 15 in S. pimpinellifolium, and 16 in S. lycopersicoides) were analyzed. The phylogenetic analysis showed that the all HVA22 proteins from the family Solanaceae were divided into three branches. The identified 45 HVA22 genes were grouped into four subfamilies, which displayed similar number of exons and expanded in a fragmentary replication manner. The distribution of HVA22 genes on the chromosomes of the three wild tomato species was also highly similar. RNA-seq and qRT-PCR revealed that HVA22 genes were expressed in different tissues and induced by drought, salt, and phytohormone treatments. These results might be useful for explaining the evolution, expression patterns, and functional divergence of HVA22 genes in Lycopersicon.