Rice Calcineurin B-Like Protein-Interacting Protein Kinase 31 (OsCIPK31) Is Involved in the Development of Panicle Apical Spikelets.

Yongbin Peng,Yongxiang Liao,Que Bai,Chaojian Gu,Xiaoqiong Chen,Xianjun Wu,Peizhou Xu,Tingkai Wu,Asif Ali,Hongyu Zhang,Xiaoshu Deng,Feixue Hou

doi:10.3389/fpls.2018.01661

Abstract

Panicle apical abortion (PAA) causes severe yield losses in rice production, but details about its development and molecular basis remain elusive. Herein, a PAA mutant, paa1019, was identified among the progeny of an elite indica maintainer rice line Yixiang 1B (YXB) mutagenized population obtained using ethyl methyl sulfonate. The abortion rate of spikelets in paa1019 was observed up to 60%. Genetic mapping combined with Mutmap analysis revealed that LOC_Os03g20380 harbored a single-bp substitution (C to T) that altered its transcript length. This gene encodes calcineurin B-like protein-interacting protein kinase 31 (OsCIPK31) localized into the cytoplasm, and is preferentially expressed in transport tissues of rice. Complementation of paa1019 by transferring the open reading frame of LOC_Os03g20380 from YXB reversed the mutant phenotype, and conversely, gene editing by knocking out of OsCIPK31 in YXB results in PAA phenotype. Our results support that OsCIPK31 plays an important role in panicle development. We found that dysregulation is caused by the disruption of OsCIPK31 function due to excessive accumulation of ROS, which ultimately leads to cell death in rice panicle. OsCIPK31 and MAPK pathway might have a synergistic effect to lead ROS accumulation in response to stresses. Meanwhile the PAA distribution is related to IAA hormone accumulation in the panicle. Our study provides an understanding of the role of OsCIPK31 in panicle development by responding to various stresses and phytohormones.

Highlights

Plant architectural features (Wang and Li, 2008), especially panicle structure, size, and shape (Sakamoto and Matsuoka, 2004), are the major factors influencing grain yield, and improving panicle architecture is an important goal in rice (Oryza sativa) breeding programs (Sakamoto and Matsuoka, 2008)
Unlike WT plants in which all spikelets were developed normally, the development of more than 60% of apical spikelets growth was arrested in paa1019 (Figure 1C and Supplementary Figure S1D)
Panicle development is crucial for grain yield in rice, and Panicle apical abortion (PAA) often causes yield losses during rice production

Summary

Introduction

Plant architectural features (Wang and Li, 2008), especially panicle structure, size, and shape (Sakamoto and Matsuoka, 2004), are the major factors influencing grain yield, and improving panicle architecture is an important goal in rice (Oryza sativa) breeding programs (Sakamoto and Matsuoka, 2008). RCN1 and RCN2, rice homologs of TERMINAL FLOWER/CENTRORADIALIS (TFL/CEN) that promote indeterminate inflorescence on branch and spikelet meristems in Arabidopsis and Antirrhinum, respectively (Bradley et al, 1996, 1997), lead to indeterminate inflorescence and a more branched panicle when ectopically expressed (Nakagawa et al, 2002). These indeterminacy inhibiting and promoting factors interact with each other (Bradley et al, 1996)

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Results

Conclusion