Genetic Analysis And Gene Mapping Of A Dwarf Mutant With Yellow Leaf In Rice (Oryza Sativa L.)

Rice height characters are one of the most important traits of rice. It is necessary for rice genetics and breeding to discover and research new dwarf gene. A dwarf mutant with yellow leaf was founded in rice breeding farm. With several semi-dwarf variety and a tall variety, some research about the dwarf mutant were carried out. The main results are summarized as below:l.The mutant in the seeding and the shooting stage were separately treated with gibberellin acid (GA3), it was sensitive to GA3 treatment in two stage. The height of the mutant increased and did not recover to the normal height. Treated with GA3, the seed setting rate of the mutant was improved.2.In this study, Genetic analysis for the mutant in FI and Fa population revealed that the dwarfism is controlled by two recessive genes. A dwarf gene was sd-1, the other was not. It was concluded that the mutant's genotype was sd-lsd-ld-w(t)d-w(t), and there was epitatio recessiveness to the gene of Sd-1 and sd-1.3.With the near isogenic lines (NILs) of the mutant, the effection of the dwarf mutant were researched, the reduction of plant height in the presence of dwarfing gene is mainly expressed through the shortening on the lengths of three upper internodes. The shortening of panicle and the increase of tiller are probably due to the pleiotropy of the dwarfing gene.4.Bulked segregant method and co-segregation analysis in F2 population were used to screen molecular markers linked with the dwarf gene. It was showed that the dwarf gene lay in chromosome 9. The result showed that the marker RM316 in chromosome was linked with the target gene, and the genetic distance is 8.1cM. Thus this research is the first to map a new dwarf recessive gene molecular linkage map, which wastemporarily designated as d-w(t), the genotype of the mutant was sd-lsd-ld-w(t)d-w(t). 5.The study on the phenomenon of yellow leaf. Leaf of the mutant started to appear yellow on the top after about a month growth. The chlorophyll content in the leaf of mutant was lower than that of normal plant, and the chloroplast began to disaggregate observing through microscope. Root vigor of the mutant was under the level of normal plant.