Purine nucleotide biosynthetic gene GARS controls early chloroplast development in rice (Oryza sativa L.)
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GARS encodes an enzyme catalyzing the second step of purine nucleotide biosynthesis and plays an important role to maintain the development of chloroplasts in juvenile plants by affecting the expression of plastid-encoded genes.
A series of rice white striped mutants were previously described. In this research, we characterized a novel gars mutant with white striped leaves at the seedling stage. By positional cloning, we identified the mutated gene, which encodes a glycinamide ribonucleotide synthetase (GARS) that catalyzes the second step of purine nucleotide biosynthesis. Thylakoid membranes were less abundant in the albinic sectors of mutant seedling leaves compared to the wild type. The expression levels of genes involved in chlorophyll synthesis and photosynthesis were changed. Contents of ATP, ADP, AMP, GTP and GDP, which are crucial for plant growth and development, were decreased in the mutant seedlings. Complementation and CrispR tests confirmed the role of the GARS allele, which was expressed in all rice tissues, especially in the leaves. GARS protein displayed a typical chloroplast location pattern in rice protoplasts. Our results indicated that GARS was involved in chloroplast development at early leaf development by affecting the expression of plastid-encoded genes.
KeywordsRice (Oryza sativa L.) Purine nucleotide biosynthesis Chloroplast development GARS
This research was supported by Key Laboratory of Biology, Genetics and Breeding of Japonica Rice in Mid-lower Yangtze River, Ministry of Agriculture, P.R.China, and Jiangsu Collaborative Innovation Center for Modern Crop Production, and grants from the National Key Research and Development Program of China (2016YFD0100101-08), National Transgenic Research Key Project (2016ZX08001006), and Jiangsu Science and Technology Development Program (BE2017368).
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Conflict of interest
The authors declare that they have no conflict of interest.