Rice stripe1-2 and stripe1-3 Mutants Encoding the Small Subunit of Ribonucleotide Reductase Are Temperature Sensitive and Are Required for Chlorophyll Biosynthesis.

Xiaoqiong Chen,Kangxi Du,Peizhou Xu,Xiaoyun Cui,Ling Zhu,Xianjun Wu,Xiuhua Ran,Quanju Xiang,Long Xin,Hongyu Zhang

doi:10.1371/journal.pone.0130172

Xiaoqiong Chen, Kangxi Du + Show 8 more

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https://doi.org/10.1371/journal.pone.0130172

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Abstract

We induced mutants, stripe1-2 (st1-2) and stripe1-3 (st1-3), from rice (Oryza sativa L.) Indica 9311 using Ethyl methanesulfonate (EMS). Both st1-2 and st1-3 mutants encoded the small subunit of ribonucleotide reductase 1 (RNRS1), differed in the location of the mutated base, and displayed white-stripe from the L2 stage through maturity. The mutants were sensitive to temperature, and their chlorophyll content increased with the increase in temperature; however, they did not revert to normal green leaf phenotype under field conditions. The mutant st1-2 showed loosely arranged thylakoid lamellar structure as compared with wild-type (WT) plants. Contrastingly, st1-3 displayed normal thylakoid lamellar structure, good agronomic traits, and higher yield than st1-2 but lower yield than WT. Three-dimensional structure prediction for RNRS1 indicated that the mutation in Val-171 residue in st1-2 influenced the connection of RNRS1 to iron, causing abnormal development of chloroplasts. Real-time PCR analysis showed that the expression levels associated with chlorophyll biosynthetic pathway and photosynthesis were affected in st1-2 and st1-3 at different temperatures and different developmental stages.

Highlights

Plastid and nuclear genes regulate the transformation of proplastids to photosynthetically active chloroplasts during plastid development
Different mutants show different degrees of sensitivities to temperatures, for example: v3 encoding mutant of RNRL1 is more sensitive to temperature than st1 encoding ribonucleotide reductase 1 (RNRS1)
Our study showed that rice stripe1- 3 mutant is more sensitive to temperature than rice stripe 1–2 mutant

Summary

Introduction

Plastid and nuclear genes regulate the transformation of proplastids to photosynthetically active chloroplasts during plastid development. Chloroplast protein in the plant cell is mainly encoded by nuclear genes while less than 5% is encoded by cytoplasmic genes [1, 2]. Mutations in these genes or chloroplast associated mutations cause leaf discoloration and affect seedling viability. The resulting mutants have diverse phenotypes and are variously referred to as virescent (v), stripe (st), albino, chlorina, zebra, and yellow variegated [3]. PLOS ONE | DOI:10.1371/journal.pone.0130172 June 23, 2015

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