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Plants with purple leave attain interest because of their biological importance. A new rice mutant, purple leaf (pl) was isolated from an indicia cultivar Zhenong 34, which was induced by ethyl methane sulfonate (EMS) mutagenesis. The genetic analyses substantiated that pl was corroborated by one recessive allele and confirmed by map based cloning using Insertion-Deletion (InDel) markers located on the long arm of chromosome 5. DNAseq data of the candidate part showed one bp insertion (‘C’ insertion) at +901 bp position in the 3rd exon of OsPL gene. The pl was characterized as purple leaves, sheaths and leaf senescence phenotype at late grain filling stage of growth cycle. It possessed abnormal cell with distorted chloroplasts, less chlorophyll, and increased anthocyanin content in leaves. The anthocyanin biosynthesis genes, OsPAL, OsCHS, OsANS, and OsMYB55 showed up-regulation in pl plants compared to wild type (WT). High super oxide dismutase enzyme (SOD), catalase enzyme activity (CAT), total soluble sugar (TSS) and malondialdehyde activity (MDA) were detected in the pl; contrastingly, photosynthesis linked genes were down-regulated. The germinated pl seeds showed comparatively higher temperature stress tolerance than WT. The phytohormones abscicic acid (ABA), jasmonic acid (JA) and indole acetic acid (IAA) content were increased significantly in the pl plants. This research work will be provided information on better understanding of the molecular mechanism toward the anthocyanin biosynthetic pathway in rice. Therefore, OsPL gene could be a good genetic tool in marker aided backcrossing or gene editing for improving the rice cultivation in future.

A new mutant named sdl (stripe and drooping leaf) was characterized from indica cultivar Zhenong 34 by ethylmethane sulfonate (EMS) mutagenesis. The mutant sdl exhibited development defects including stripe and drooping leaf, dwarfism and deformed floral organs. The gene SDL was found allelic to RNRS1 by map-based cloning, which was homologous to Arabidopsis TSO2 encoding the small subunit of ribonucleotide reductase. The gDNA sequencing results of sdl in mutant showed that there was a repetitive sequence insertion of 138-bp at the 475th bp in the exon. The redundant sequence was conserved in SDL homologous proteins, which contained the active site (tyrosine), as well as two amino acids glutamate and histidine involved in the binding of iron. There were fewer chloroplasts and grana lamellas in sdl leaf compared with those of wild-type. Additionally, the stripe leaves of sdl seedlings were highly sensitive to temperature, since the chlorophyll content was increased with the temperature rising. The drooping leaf of sdl might be resulted from the disappearance of vascular bundles and mesophyll cells in both leaf midrib and lateral veins. Fittingly to the phenotypes of mutant sdl, the expression levels of genes associated with photosynthesis and chlorophyll synthesis were found to be down- or up-regulated at different temperatures in mutant sdl. Also, the transcriptional levels of genes related to plant height and floral organ formation showed obvious differences between wild-type and sdl. The "SDL/RNRS1" was, hence, required for the chlorophyll biosynthesis and also played pleiotropic roles in the regulation of plant development.