OsPLS4 Is Involved in Cuticular Wax Biosynthesis and Affects Leaf Senescence in Rice

Junru Fu,Ziyang Qu,Dahu Zhou,Zhishu Jiang,Liyuan Peng,Haohua He,Xiaoli Lin,Linjuan Ouyang,Changlan Zhu,Wenbang Tang,Xiaosong Peng,Yaolong Yang,Ting Li,Jianmin Bian,Jie Xu

doi:10.3389/fpls.2020.00782

Junru Fu, Ziyang Qu + Show 13 more

Open Access

https://doi.org/10.3389/fpls.2020.00782

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Abstract

Leaf senescence is one of the most common factors that affects the growth and yield of rice. Although numerous genes affecting leaf senescence have been identified, few involved in cuticular wax synthesis have been described for rice premature leaf senescence. Here, we cloned and characterized Premature Leaf Senescence 4 (PLS4) in rice (Oryza sativa), which encodes a putative 3-oxoacyl-reductase in the fatty acid biosynthetic pathway. Subcellular localization of OsPLS4 was observed in the chloroplast. A single nucleotide substitution in OsPLS4 reduced leaf cuticular wax, and the expression levels of most wax biosynthesis-associated genes were downregulated. TEM showed chloroplast development were defective in the pls4 mutant. Further investigation revealed that the chlorophyll (Chl) content was reduced in the pls4 mutant compared with the WT and that the photosynthesis rate was lower, which caused ROS dramatic accumulation at the heading stage. These results confirmed premature leaf senescence in pls4 plants. Cold treatment indicated that the mutant was more sensitive than the WT was to cold stress. Together, all the above results indicate that the OsPLS4 mutation affects cuticular wax biosynthesis and chloroplast development in rice, causing reduced cuticular wax and premature leaf senescence.

Highlights

Rice (Oryza sativa) is one of the most important cereal crop species worldwide and is consumed by more than half of the global population
We isolated a premature leaf senescence mutant described as pls4 from a mutant library of the japonica rice variety Zhong Hua 11 (ZH11), which was generated by ethyl methyl sulfonate (EMS) treatment
After heading, the leaves color changed from green to yellow and some brown spots were visible (Figures 1B,C), and the Chl content rapidly decreased in pls4 (Figure 1D)

Summary

Introduction

Rice (Oryza sativa) is one of the most important cereal crop species worldwide and is consumed by more than half of the global population. Premature leaf senescence affects rice yields and quality by reducing photosynthetic efficiency and the accumulation of nutrients (Yang et al, 2016; Mao et al, 2017). A large number of genes involved in either Chl biosynthesis or degradation have been verified to respond to leaf senescence (Horie et al, 2009; Sato et al, 2009; Yamatani et al, 2013; Yasuhito et al, 2013). The pls mutant presents a reduced Chl content and an increased H2O2 content, the OsMTS1 encodes a methyltransferase, is required for melatonin biosynthesis in rice, and disruption of OsMTS1 can trigger premature leaf senescence (Hong et al, 2018)

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