Identification of Green-Revertible Yellow 3 (GRY3), encoding a 4-hydroxy-3-methylbut-2-enyl diphosphate reductase involved in chlorophyll synthesis under high temperature and high light in rice

Chlorophyll, a green pigment in photosynthetic organisms, is generated by two distinct biochemical pathways, the tetrapyrrole biosynthetic pathway (TBP) and the methylerythritol 4-phosphate (MEP) pathway. MEP is one of the pathways for isoprenoid synthesis in plants, with 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR) catalyzing its last step. In this study, we isolated a green-revertible yellow leaf mutant gry3 in rice and cloned the GRY3 gene, which encodes a HDR participating in geranylgeranyl diphosphate (GGPP) biosynthesis in chloroplast. A complementation experiment confirmed that a missense mutation (C to T) in the fourth exon of LOC_Os03g52170 causes the gry3 phenotype. Under high temperature and high light, transcript and protein abundances of GRY3 were reduced in the gry3 mutant. Transcriptional expression of chlorophyll biosynthesis, chloroplast development, and genes involved in photosynthesis were also affected. Excessive reactive oxygen species accumulation, cell death, and photosynthetic proteins degradation were occurred in the mutant. The content of GGPP was reduced in gry3 compared with Nipponbare, resulting in a stoichiometric imbalance of tetrapyrrolic chlorophyll precursors. These results shed light on the response of chloroplast biogenesis and maintenance in plants to high-temperature and high-light stress.