MiR156a-targeted SBP-Box transcription factor SlSPL13 regulates inflorescence morphogenesis by directly activating SFT in tomato.

Long Cui,Jie Ye,Zhibiao Ye,Fangyan Zheng,Fangming Xiao,Changxing Li,Junhong Zhang,Chunli Zhang,Jiafa Wang

doi:10.1111/pbi.13331

Abstract

The inflorescences and lateral branches of higher plants are generated by lateral meristems. The structure of the inflorescence has a direct effect on fruit yield in tomato (Solanum lycopersicum). We previously demonstrated that miR156a plays important roles in determining the structures of the inflorescences and lateral branches in tomato by suppressing the expression of the SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) transcription factor gene family. However, information on regulatory pathways associated with inflorescence morphogenesis is still lacking. In this study, we demonstrate that SPL13 is the major SPL involved in miR156a‐regulated tomato inflorescence structure determination and lateral branch production. Suppressing the expression of SPL13 in tomato increases the number of inflorescences on vegetative branches and lateral branches, decreases the number of flowers and fruit, and reduces fruit size and yield. Genetic and biochemical evidence indicate that SPL13 controls inflorescence development by positively regulating the expression of the tomato inflorescence‐associated gene SINGLE FLOWER TRUSS (SFT) by directly binding to its promoter region. Thus, our findings provide a major advance to our understanding of the miR156a‐SlSPL‐based mechanism that regulates plant architecture and yield in tomato.

Highlights

Plant architecture is an important determinant of crop yield
We found that the suppression of the SPL13 gene by RNA interference (RNAi) and the overexpression of miR156a in tomato plants produced similar phenotypes (Figure 1, Figure S1a)
The number of lateral branches produced by the SPL13-RNAi and 35S-miR156a lines was about twofold more than the wild-type (WT) plants (Ailsa Craig) (Figure 1g)

Summary

Introduction

Plant architecture is an important determinant of crop yield. The architecture of higher plants is established by lateral meristems, which fundamentally influences the lives of plants (Gallavotti et al, 2004; Martin-Trillo et al, 2011). The SPL transcription factor IPA1 regulates plant architecture by influencing rice tillering (Jiao et al, 2010; Lu et al, 2013; Miura et al, 2010). The miR156-TaSPL3/17 module can regulate plant architecture in bread wheat (Liu et al, 2017). The miR156-SPL4 module predominantly regulates axillary bud formation (Gou et al, 2017). SBP-box transcription factor genes UNBRANCHED3 (UB2) and UNBRANCHED3 (UB3) affect yield traits by regulating the rate of lateral primordia initiation (Chuck et al, 2014; Du et al, 2017, 2017). The SPL genes encode important regulators of plant architecture traits in crop plants

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Conclusion