Heat shock factors in tomatoes: genome-wide identification, phylogenetic analysis and expression profiling under development and heat stress.

The HSF (heat shock factor) gene family contains highly conserved plant-specific transcription factors that play an important role in plant high-temperature stress responses. The present study aimed to characterize the HSF transcription factor genes in tomato (Solanum lycopersicum), which is an important vegetable crop worldwide and the model plant for fruit development studies. Twenty-six SlyHSF genes were identified in tomato, and the phylogenetic analysis showed the possible evolution profile of subgroups among in the plant kingdom. A new group O was identified that involved HSF genes in primitive plant species, like in the green algae, mosses and lycophytes. The gene structure and motifs of each SlyHSF were comprehensively analyzed. We identified orthologous, co-orthologous and paralogous HSF gene pairs in tomato, Arabidopsis and rice, and constructed a complex interaction network among these genes. The SlyHSF genes were expressed differentially in different species and at a higher level in mature fruits. The qPCR analysis was performed and showed SlyHSF genes greatly participate in plant heat tolerant pathways. Our comprehensive genome-wide analysis provided insights into the HSF gene family of tomatoes.