ZjSEP3 modulates flowering time by regulating the LHY promoter

Weilin Gao,Zhiguo Liu,Chaoling Xue,Jin Zhao,Jiurui Wang,Yao Zhang,Liman Zhang,Mengjun Liu

doi:10.1186/s12870-021-03305-x

Abstract

BackgroundSEPALLATA3 (SEP3), which is conserved across various plant species, plays essential and various roles in flower and fruit development. However, the regulatory network of the role of SEP3 in flowering time at the molecular level remained unclear.ResultsHere, we investigated that SEP3 in Ziziphus jujuba Mill. (ZjSEP3) was expressed in four floral organs and exhibited strong transcriptional activation activity. ZjSEP3 transgenic Arabidopsis showed an early-flowering phenotype and altered the expression of some genes related to flowering. Among them, the expression of LATE ELONGATED HYPOCOTYL (AtLHY), the key gene of circadian rhythms, was significantly suppressed. Yeast one-hybrid (Y1H) and electrophoretic mobility shift assays (EMSAs) further verified that ZjSEP3 inhibited the transcription of AtLHY by binding to the CArG-boxes in its promoter. Moreover, ZjSEP3 also could bind to the ZjLHY promoter and the conserved binding regions of ZjSEP3 were found in the LHY promoter of various plant species. The ectopic regulatory pathway of ZjSEP3-AtLHY was further supported by the ability of 35S::AtLHY to rescue the early-flowering phenotype in ZjSEP3 transgenic plants. In ZjSEP3 transgenic plants, total chlorophyll content and the expression of genes involved in chlorophyll synthesis increased during vegetative stages, which should contribute to its early flowering and relate to the regulatory of AtLHY.ConclusionOverall, ZjSEP3-AtLHY pathway represents a novel regulatory mechanism that is involved in the regulation of flowering time.

Highlights

SEPALLATA3 (SEP3), which is conserved across various plant species, plays essential and various roles in flower and fruit development
Phylogenetic tree construction and conserved motifs of ZjSEP3 To better understand the relation of ZjSEP3 and SEP proteins from other plant species, a phylogenetic tree was constructed in this study (Fig. 1A), showing that ZjSEP3 clustered with the SEP3 proteins of other species
Multiple sequence alignment of ZjSEP3 and its homologs from eight other species revealed that these proteins contained highly conserved MADS and K domains (Fig. 1B), indicating that SEP3 is conserved in the evolution of plants

Summary

Introduction

SEPALLATA3 (SEP3), which is conserved across various plant species, plays essential and various roles in flower and fruit development. The regulatory network of the role of SEP3 in flowering time at the molecular level remained unclear. Researchers have subsequently discovered that floral organs are regulated by E-class genes [3]. E-class (SEPALLATA, SEP) genes play essential and various roles in reproductive organ development [4,5,6]. The effects of SEP-class genes on the regulation of flowering time vary. SEP3 genes of some other species have been found to regulate flowering time [11,12,13,14]. Little is known about the regulatory network of the role of SEP3 in flowering time at the molecular level

Methods

Results

Conclusion