Regulatory Role of OsMADS34 in the Determination of Glumes Fate, Grain Yield, and Quality in Rice.

Deyong Ren,Dali Zeng,Li Zhu,Zizhuang Li,Zhennan Qiu,Yujia Leng,Longbiao Guo,Yuchun Rao,Guang Chen,Dawei Xue,Liwen Wu,Guangheng Zhang,Qiankun Xu,Qian Qian,Zhenyu Gao,Guojun Dong,Jiang Hu

doi:10.3389/fpls.2016.01853

Abstract

Grasses produce seeds on spikelets, a unique type of inflorescence. Despite the importance of grass crops for food, the genetic mechanisms that control spikelet development remain poorly understood. In this study, we used m34-z, a new mutant allele of the rice (Oryza sativa) E-class gene OsMADS34, to examine OsMADS34 function in determining the identities of glumes (rudimentary glume and sterile lemma) and grain size. In the m34-z mutant, both the rudimentary glume and sterile lemma were homeotically converted to the lemma-like organ and acquired the lemma identity, suggesting that OsMADS34 plays important roles in the development of glumes. In the m34-z mutant, most of the grains from the secondary panicle branches (spb) were decreased in size, compared with grains from wild-type, but no differences were observed in the grains from the primary panicle branches. The amylose content and gel consistency, and a seed-setting rate from the spb were reduced in the m34-z mutant. Interesting, transcriptional activity analysis revealed that OsMADS34 protein was a transcription repressor and it may influence grain yield by suppressing the expressions of BG1, GW8, GW2, and GL7 in the m34-z mutant. These findings revealed that OsMADS34 largely affects grain yield by affecting the size of grains from the secondary branches.

Highlights

In most flowering plants, flowers consist of sepals, petals, stamens, and pistils, which are arranged in concentric whorls (Ohmori et al, 2009)
These results suggest that OsMADS34 may be a regulatory factor that modulates grain size in the spb in rice
No difference in cell number was found between the wild-type and the m34-z mutant. qPCR analyses showed that OsMADS34 regulated the expression of cell expansion-related genes, in agreement with the phenotypic observations

Summary

Introduction

Flowers consist of sepals, petals, stamens, and pistils, which are arranged in concentric whorls (Ohmori et al, 2009). Arabidopsis thaliana has four functionally redundant E-class genes (SEP1, SEP2, SEP3, and SEP4) that determine floral meristem fate and floral organ identity (Pelaz et al, 2000; Ditta et al, 2004; Li H. et al, 2010). LHS1/OsMADS1 determines the identities of four whorls of floral organs and affects the determinacy of the floral meristem (Jeon et al, 2000; Hu Y. et al, 2015). The osmads mutant displays an abnormal inflorescence with an elongated sterile lemma, suggesting that OsMADS34 controls spikelet and inflorescence morphology mainly by mainly regulating the identity of the sterile lemma and number of branches of the panicle (Gao et al, 2010; Kobayashi et al, 2010; Lin et al, 2014; Zhang and Yuan, 2014)

Methods

Results

Conclusion