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Leaf-color mutants in rice (Oryza sativa L.) are excellent models for studying chlorophyll biosynthesis and chloroplast development. In this study, a yellow-green-leaf mutant generated by 60Co irradiation, ygl9311, was isolated: it displayed a yellow-green leaf phenotype during the complete growth cycle. Compared with the wild type, the photosynthetic pigment contents of leaves in ygl9311 were significantly reduced, and chloroplast development was retarded. Genetic analysis indicated that the ygl9311 phenotype was controlled by a single recessive nuclear gene. Map-based cloning and transcriptome sequencing analysis suggested that the candidate gene was OsChlC1 (BGIOSGA012976), which encodes a Mg-chelatase I subunit. The results of CRISPR/Cas9 system and RNAi knockout tests show that mutation of OsChlC1 could reproduce the phenotype of yellow-green leaves of the mutant ygl9311. In conclusion, the novel rice leaf-color gene OsChlC1 affects the content of chlorophyll in rice, showing a relatively conserved function in indica and japonica rice cultivars. [ABSTRACT FROM AUTHOR]

Fatty acids (FAs) have been implicated in signaling roles in plant defense responses. We previously reported that mutation or RNAi-knockdown (OsSSI2-kd) of the rice OsSSI2 gene, encoding a stearoyl acyl carrier protein FA desaturase (SACPD), remarkably enhanced resistance to blast fungus Magnaporthe oryzae and the leaf-blight bacterium Xanthomonas oryzae pv. oryzae (Xoo). Transcriptomic analysis identified six AAA-ATPase family genes (hereafter OsAAA-ATPase1–6) upregulated in the OsSSI2-kd plants, in addition to other well-known defense-related genes. Here, we report the functional analysis of OsAAA-ATPase1 in rice's defense response to M. oryzae. Recombinant OsAAA-ATPase1 synthesized in Escherichia coli showed ATPase activity. OsAAA-ATPase1 transcription was induced by exogenous treatment with a functional analogue of salicylic acid (SA), benzothiadiazole (BTH), but not by other plant hormones tested. The transcription of OsAAA-ATPase1 was also highly induced in response to M. oryzae infection in an SA-dependent manner, as gene induction was significantly attenuated in a transgenic rice line expressing a bacterial gene (nahG) encoding salicylate hydroxylase. Overexpression of OsAAA-ATPase1 significantly enhanced pathogenesis-related gene expression and the resistance to M. oryzae; conversely, RNAi-mediated suppression of this gene compromised this resistance. These results suggest that OsAAA-APTase1 plays an important role in SA-mediated defense responses against blast fungus M. oryzae. [ABSTRACT FROM AUTHOR]