Genetic Analyses And Gene Tagging Of Two Plant Height Mutants In Rice And New Methods Controlling Rice Kernel Smut Disease

Plant height was one of the important agronomic traits of rice. In this thesis, two new plant height mutants of rice were analyzed genetically, and mutant genes were tagged by using microsatellite markers, which results were as the following:SSR Polymorphic analysis demonstrated that a small grain dwarf mutant 162d derived from a semidwarf variety Shuhui 162 through gene mutation. The mutant had about a quarter of normal plant height and a quarter of normal grain size, compared with the near isogenic line Shuhui 162. Genetic analysis showed that the small grain dwarfism of 162d was controlled by one recessive gene. Microsatellite analysis suggested that the mutant gene located on the short arm of rice chromosome 3, 3. 5cM from microsatellite marker RM218. Therefore, the mutant gene of 162d was considered to be a new small grain dwarf gene in rice and designated tentatively as dl62(t}.SSR Polymorphic analysis demonstrated that a long-culm mutant D1ll derived from hybrid progeny of two semidwarf varieties, 6442S-7 and Shuhui 881, through mutation. D1ll was 83% higher than its parent Shuhui 881. Genetic analysis showed that the long-culm trait of D1ll was controlled by one dominant gene. Therefore, it was considered that D1ll was the first example of dominant long-culm mutant derived from a semidwarf variety in rice. AlLelism test showed that the Long-culm gene of D1ll was Linked closeLy or alleLic to that of Long-cuLm controLvariety Nanjing 6. Microsatellite analysis suggested that the long-culm gene of D1ll located on the long arm of rice chromosome 1, 21.9cM from microsatellite marker RM302. However, analysis results of culm characteristics indicated that the long-culm gene of D1ll might act earlier and more strongly than that of Nanjing 6. So the long-culm mutant gene of D1ll was considered to be a new long-culm gene different to that of Nanjing 6 in rice and designated tentatively as LC(t).In other hand, according to the state that rice kernel smut disease harmed seed production of hybrid rice seriously, we developed a kind of highly effective composite chemical, designated as "Kanghei 95" , which was very effective to controlling this disease. In the recent years, we extended widely the new methods controlling rice kernel smut disease, of which Kanghei 95 was as the center. As a result, significant social and economic benefits were achieved.