Overexpression of SlPRE5, an atypical bHLH transcription factor, affects plant morphology and chlorophyll accumulation in tomato

Abstract

The basic helix–loop–helix (bHLH) transcription factors play vital regulatory roles in a series of metabolic, physiological, and developmental processes of plants. Here, SlPRE5, an atypical bHLH gene, was isolated from tomato. SlPRE5 was noticeably expressed in young leaves, sepals, and flowers. SlPRE5-overexpressing plants exhibited rolling leaves with reduced chlorophyll content, increased stem internode length, leaf angle, and compound leaf length. The water loss rate of mature leaves and the content of starch were significantly reduced, while the content of gibberellin was significantly increased in transgenic plants. Yeast two-hybrid and bimolecular fluorescence complementation (BiFC) showed that SlPRE5 could interact with SlAIF1, SlAIF2, and SlPAR1. qRT-PCR and RNA-seq results revealed that the expression levels of genes related to chloroplast development, chlorophyll metabolism, gibberellin metabolism and signal transduction, starch, photosynthesis, and cell expansion were significantly altered in SlPRE5-overexpression plants. Collectively, our results suggest that SlPRE5 is a crucial transcription factor involved in plant morphology and chlorophyll accumulation in tomato leaves.