ITRAQ-Based Analysis of Proteins Co-Regulated by Brassinosteroids and Gibberellins in Rice Embryos during Seed Germination

Qian-Feng Li,Peng Zhou,Li-Chun Huang,Jin-Dong Wang,Xiao-Lei Fan,Ke Wei,Qiao-Quan Liu,Min Xiong,Chang-Quan Zhang

doi:10.3390/ijms19113460

Abstract

Seed germination, a pivotal process in higher plants, is precisely regulated by various external and internal stimuli, including brassinosteroid (BR) and gibberellin (GA) phytohormones. The molecular mechanisms of crosstalk between BRs and GAs in regulating plant growth are well established. However, whether BRs interact with GAs to coordinate seed germination remains unknown, as do their common downstream targets. In the present study, 45 differentially expressed proteins responding to both BR and GA deficiency were identified using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis during seed germination. The results indicate that crosstalk between BRs and GAs participates in seed germination, at least in part, by modulating the same set of responsive proteins. Moreover, most targets exhibited concordant changes in response to BR and GA deficiency, and gene ontology (GO) indicated that most possess catalytic activity and are involved in various metabolic processes. Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis was used to construct a regulatory network of downstream proteins mediating BR- and GA-regulated seed germination. The mutation of GRP, one representative target, notably suppressed seed germination. Our findings not only provide critical clues for validating BR–GA crosstalk during rice seed germination, but also help to optimise molecular regulatory networks.

Highlights

As sessile organisms, plants need to modulate their growth and development constantly to adapt to the changing environment
We generated a series of chromosome segment substitutional lines (CSSLs) using the japonica variety Nip as the recipient parent and indica variety 9311 as the donor parent
Two different rice materials were used for proteomic experiment; japonica cultivar Nipponbare (Nip) that has a functional SD1 (SEMIDWARF1) gene (Nip (SD1)), and a near-isogenic line (NIL) of SD1 locus generated by introduction of a mutated sd1 allele from indica cultivar 9311 into the Nip genetic background, designated Nip

Summary

Introduction

Plants need to modulate their growth and development constantly to adapt to the changing environment. A new BR-responsive miRNA-target module was identified, that is BR could promote the expression of OsGAMYBL2 by suppressing the level of OsmiR159d Both OsGSK2, a key negative player in BR signaling, and SLR1, a rice DELLA protein, could directly interact with OsGAMYBL2 to modulate its stability and activity, respectively, to coordinate the regulation of BR and GA in plant growth and development [26]. It remains obscure whether these proposed models and characterised integrators are suitable for other developmental process, such as seed germination. BR and GA signal transduction and downstream responses are affected by the developmental context

Methods

Results

Conclusion