The Relationship Between The Short Growth Period Gene And Other Heading Date Genes In Rice

Rice, with a trait of short growth period, meets the various needs of agricultural production, thus the excavation and utilization of earliness genes have a great significance in the genetics and breeding of rice. A extremely short growth period mutant, which is temporarily named short growth period (sgp(t)), was found in the T1 progenies of transgenic plants of Minghui 86, an lateness indica rice restorer line. Preliminary gene mapping result indicated that the SGP(t) gene may be a new important gene in controlling rice floral. In this study, we observed the growth and developmental characteristic and analysised the flowering regulation pathway which the SGP(t) gene may control in rice, we compared the leaf emergence rate of main stem between wild-type Minghui 86 plants and sgp(t) mutants under long-day conditons 120 days after sowing. These results demonstrated that the SGP(t) gene controls the floral transition in rice, but not its growth rates. We regularly observed the differentiation of main stem of stem apex between wild-type Minghui 86 plants and sgp(t) mutants, than we showed that the mutant of the SGP(t) gene reduced the vegetative phase of rice in a large extent, shortened the reproductive phase of rice to a certain degree, little affected the maturation phase of rice. Gene expression analysis of leaf blade in different developmental stages of wild-type Minghui 86 plants and sgp(t) mutants, suggested that the SGP(t) gene mainly involved in the control of rice florigen gene, Hd3a, by upregulating Hd3a and its downstream genes OsMADS14 and OsMADS15 to promote flowering transition in rice. Thereby, the SGP(t) gene was a critical gene playing a role in regulating heading date in rice.