Genetical Analysis And Molecular Mapping Of Beneficial Genes In Rice

Genetical analysis and molecular mapping for beneficial genes in rice are among major topics in rice genetic and breeding research. In the present study, two new semidwarf genes were found from Chinese local rice varieties Qian-nong (QN) and Te-ai (TA), respectively, and a new gene Wbph6(t) from Yunnan landrace Gui-yi-gu (GYG) conferring resistance to whitebacked planthopper was mapped onto the short arm of Chromosome 11.1. Genetical analysis of dwarfism in two local varieties. Results indicated that the dwarfism in QN and TA were controlled by two recesive dwarf genes, respectively, of which one was allelelic to sd-1 and the other was non-allelic to sd-1. Two lines XQA (Xin-qian-ai) and XTA (Xin-te-ai) possessing new semi-dwarf genes sd-q(t) and sd-t(t) from QN and TA, respectively, were selected.2. Allelism test between sd-q(t) and other genes conferring dwarfism or semi-dwarfism indicated that sd-q(t) was non-allelic to d-29, d-32, d-59, sd-g, sd-6 and d-1.3. The response to gebberellic acid (GA3) of rice lines carrying different dwarf genes and gene combinations were studied at seedling and shooting stages. Among the dwarf genes tested, the new semi-dwarf gene sd-g(t) was insensitive to GAa, whereas most of the others were sensitive. The sensitivety to GAs from the higher to the lower ranked as : d-59, D-53, sd-1 (/nd/ca) , sd-1 and sd-t(t) combination (TA), d-29, multi-gene combination, d-1, Sd-1, sd-6,d-32, sd-g, sd-1 andsd-q(t) combination (QN) and sd-q(t) (XQA).4. XQA carrying the new semi-dwarf gene sd-qr(t) was shown to have promising characterises on agronomic traits such as fertility, grain weight and grain number per panicle, suggesting that sd-q(t) might be utilized in rice breeding in replacement of sd-1 gene.5. A rice population consisting of 90 TN1 / GYG F3 lines was employed to analyze linkage between DMA markers and a new gene Wbph6(t) conferring resistance to the whitebacked planthopper. By employing the mapping approach of bulked extremes and recessive class, Wbph6(i) was mapped onto the short arm of Chromosome 11 with a genetic distance of 21.2 cM to SSLP marker RM167.