Genetic Analysis And Molecular Mapping Of Mutants Sd-z(t) And Pse-z(t) In Rice

Dwarfism is one of the most important yielding traits in rice. Utilization of dwarf rice varieties was one of the greatest achievements in rice breeding in the 20^th century. Identification and utilization of non-sd1 gene are among major topics in rice genetic and breeding research. Study and utilization of dwarf mutants timely in rice would help us resolve the genetic frangibility caused by simplification of the use of dwarf gene in rice breeding. In the present study, by genetic analysis and genetic background improvement, a new semi-dwarf gene, which would be useful in rice breeding, was found from semi-dwarf mutants from ZH11. Genetic analysis of a premature senescence mutant Pse-z(t) was made, and the gene Pse-z(t) was preliminary mapped onto chromosome 11.1. The agronomic traits and genetic character of dwarfism of XHA and AZH were studied. The results showed that the dwarfism was controlled by single recessive gene in those two mutants. The semi-dwarf gene in AZH was allelic to sdl, while the one in XHA was non-allelic to sd1, Maybe sdl is down -regulated by sd-z(t) in metabolism pathway of GAs.2. Allelism tests between sd-z(t) and several other semi-dwarf genes indicated that sd-z(t) was non-allelic to sd-g, sd-q, d-59, sd-6. XHA showed responsiveness to GA3 and PP333 at seeding stage. The result of photomorphogenic reaction showed sd-z(t) was consistent with dwarfism that resulted from a deficiency in gibberellin (GA) plant hormones.3. Character expressions of sd-z(t) were studied. XHA has excellent agronomic traits. Also there are good combination of large grain size with semi-dwarfism controlled by sd-z(t) and good associations between the semi-dwarfism and grain number per panicle and the semi-dwarfism and high seed setting rate. The side effect such as the reduction of panicle and grain number per panicle can be changed by the improvement of genetic background. All those suggested that sd-z(t) can be utilized in rice breeding.4. Genetical analysis and preliminary mapping of the mutant "ZH-premature senescence " were conducted. Results showed that the premature senescence trait was controlled by single dominant gene. With SSR markers and wild type plants from F2 population, the Pse-z(t) was located on the short arm of chromosome 11,about 1.9 cM genetic distance between marker RM5128 and RM116.