Phytohormone Sensitivity Analysis And Genetic Mapping Of A New Leaf Angle Gene In Rice (Oryza Sativa L.)

Rice (Oryza sativa L.) is the stable food for world and plays an important role in China. High and stable yield of rice is an important guarantee for food security in our country. An ideal plant architecture is the key factor for rice high yield. Having smaller leaf angle and erecter functional leaf in later growing stage are required in rice, which is benefit for photosynthesis and yield.1. A short-erect leaf rice mutant (ser) isolated from a mutant pool generated from Thai aromatic rice "Khao Dawk Mali 105" (KDM105) by radiation mutagenesis was used to identify the agronomic traits, and test the phytohormone sensitivity and genetic mapping. Compared with the wild type, ser had shorter leaf and smaller leaf angle. The mutant had a small angle between the flag leaf and culm,104.6° smaller than the wild type. During the whole growing stage of ser, it had a dynamic leaf angle. It had loose leaf, before 5-leaf stage, and smaller angle and upright leaf after that. Most of traits such as length and width of leaf, height of sulm during later growing stage of ser were similar to that of D1, however, result of phytohormone sensitivity tests showed that it was sensitive to Gibberellic acid (GA), and insensitive to Brassinolide (BR) which is different from that of Dl.2. Classical genetic analysis on F2 populations derived from ser/L604 and ser/08CR578 indicated that the short-erect leaf phenotype of ser was controlled by a single recessive gene, ser. Allelic tests between ser and other mutants indicated that ser was a previously unknown locus involved in rice leaf inclination regulation.3. The ser gene was firstly identified with 500 pairs of simple sequence repeat (SSR) markers covering the whole genome by BSA with F2 populations which derived from F1s of ser/08CR578 and ser/L604. In F2 population of ser/08CR578, ser gene was located on the long arm of Chromosome 5 between RM3437 and RM5454, with genetic distance of 5.3 cM and 1.5 cM respectively, and co-segregated with RM18532. In F2 population of ser/L604, ser gene was located on the long arm of Chromosome 5 between RM18504 and RM1237, with genetic distance of 1.5 cM and 2.1 cM respectively, and co-segregated with RM18532 as well.The study laid a foundation for further fine-mapping and cloning of ser gene, and would be contributed to the clarification of regulation mechanism of leaf angle, and supply genetic resource for breeding high-yielding rice.