Transcriptome Analyses Reveal the Key Regulators of Tomato Compound Leaf Development

Abstract

Leaves are one of the organs involved in plant assimilation and transpiration. Different leaf development processes can result in different leaf shapes. Tomato plants have typical compound leaves. It is helpful to explore the regulatory factors affecting the leaf development and morphogenesis of tomatoes to cultivate varieties with high photosynthetic efficiency. We used the typical tomato leaf shape mutants Petroselinum (Pts), Trifoliate (tf2), and Entire (e), which showed a gradual decrease in leaflet number and compound leaf complexity. Transcriptome sequencing was performed to analyze the key differentially expressed genes (DEGs) among the 3 groups, which revealed 2393, 1366, and 1147 DEGs in Pts/VF36, tf2/CR, and e/AC, respectively. We found 86 overlapping DEGs among the 3 groups. In addition, we found that the mutation of Pts, tf2, and e affected not only leaf morphology but also the wax, fatty acid, and abscisic acid pathways during growth and development. An RT-qPCR analysis during leaf primordium development revealed three transcription factors (bHLH079, WRKY44, and WRKY76) and three hormone-regulated genes (IAA-amino acid hydrolase, Gibberellin2ox7, and Gibberellin20ox) that were differentially expressed in the transcriptome. Using virus-induced gene silencing (VIGS), we observed the leaf shape of VIGS plants and found that bHLH079, IAA-amino acid hydrolase, Gibberellin2ox7, Gibberellin20ox, WRKY44, and WRKY76 were the endogenous regulators influencing tomato compound leaf development. This study provides a promising direction for revealing the molecular regulation mechanism underlying compound leaf development in tomatoes.