Jasmonic acid deficiency leads to scattered floret opening time in cytoplasmic male sterile rice Zhenshan 97A.

Hanlai Zeng,Chan Xia,Michael Riemann,Changxi Yin,Li Liu,Xie Zhou,Zhengshan Zou,Ying He,Ke Qian

doi:10.1093/jxb/erx251

Abstract

Cytoplasmic male sterile (CMS) rice has been widely used for hybrid rice seed production in China. However, CMS rice suffers from undesirable flowering habits including scattered floret opening time (FOT), which causes different FOTs among parental rice plants and greatly reduces hybrid rice seed production. Little is known about the mechanism of scattered FOT in CMS rice. Our results demonstrate that scattered FOT in CMS rice Zhenshan 97A (ZS97A) resulted from the lack of a driving force to open florets, which was directly caused by retarded lodicule expansion. Our results indicate that retarded lodicule expansion in ZS97A was caused by reduced water accumulation due to retarded accumulation of osmotic regulation substances (ORSs). Further, the retardation in accumulation of ORSs and water were caused by jasmonic acid (JA) deficiency, resulting from down-regulation of OsAOC expression. Applying JA restored scattered FOT in ZS97A by promoting ORS and water accumulation, and inducing the expansion of the lodicules. Taken together, JA deficiency inhibited lodicule expansion by retarding the accumulation of ORSs and water, leading to scattered FOT in CMS rice ZS97A.

Highlights

Rice (Oryza sativa L.) is a major staple food that feeds more than half of the human population (Delseny et al, 2001)
Our results demonstrate that scattered floret opening time (FOT) in Cytoplasmic male sterile (CMS) rice Zhenshan 97A (ZS97A) resulted from the lack of a driving force to open florets, which was directly caused by retarded lodicule expansion
We provide evidence that scattered FOT in CMS rice ZS97A was caused by retarded expansion of lodicules via reduced water accumulation, which resulted from retarded osmotic regulation substance (ORS) accumulation caused by jasmonic acid (JA) deficiency in the lodicules

Summary

Introduction

Rice (Oryza sativa L.) is a major staple food that feeds more than half of the human population (Delseny et al, 2001). Hybrid rice takes advantage of heterosis (hybrid vigor), which has been successfully utilized in many countries, leading to 10–20% yield increase over inbred varieties (Cheng et al, 2007). Cultivating hybrid rice is an effective approach to significantly increase grain yield (Zhang et al, 2013). During hybrid rice seed production, floret opening time (FOT) of almost all cytoplasmic male sterile (CMS) rice is scattered, whereas FOT of male fertile rice (maintainer and restorer lines) is centralized, with all florets opening during a particular time of day. The different FOTs among parental rice plants generally lead to a low rate of cross-pollination and low yield of hybrid rice seed production

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Results

Conclusion