Establishment Of Somaclonal System For Oryza Sativa L.Zhu-1S And Obtainment Of Its Dwarfing Variants

Zhu- iS is a indica malesterile line which was bred lately and widely cultivated because of its low critical temperature of fertility and high ability of resistance, as well as wide cross-compatibility. But it is higher than expected. In order to get a dwarfing variant, somaclonal system was established and 3 expected dwarfing variant lines were obtained from somaclonal variation. In addition, some research on its underlying reason for dwarfing was conducted. The main results were as follows:1 Establishment of somacolonal system Callus was induced, subcultured and regenerated in the MS basic media with different hormones in different concentration. The result showed that young inflorescence was the better explant compared to mature seed. MS+2,4-D2mg/L was the best induce media. Just the same as high concentration of 2,4-D , less 2,4-D would inhibit the induction and proliferation of callus. Though it inhibited the callus induction and proliferation, 6-BA could improve the ability of differentiation of callus. MS+2,4-D2mg/L+6-BAO.2mg/L was suitable for subculture while MS+6BA2mg/L for regeneration. Roots formed easily in both MS+NAAO.5mg(L+IAAO.5mg/L and M5+NAAO.25mg/L+IAAO.25mg/L in different rates. The frequency of regeneration was the highest when the callus was subcultured for 60 days.2.Obtainment of dwarfing variants. The plant in vitro were planted in field.Three somaclonal variant lines桽V5, SV1O and SV14 were selected out from the R2 and R3 generations. The plant height of the three variant lines of R2 was 43.5, 49.3, 46.3cm each. Except lowering in height, all other agronomic traits of variant lines and Fl generation of variant line and restorer lines were similar to the control. Critical temperature was just the same. Though full grains and total grains per panicle, fertility and 1000-grain weight decreased a little, the yield increased a little as a result of the increase of total panicles per hole. With the observation of the traitS inheritance of R2 and R3, no drift was found.3.analysis of the cause of dwarfing Many differential protein binds were discovered between SV5, SV2 and control from the result of SDS-PAGE experiment. two differential bind whose RI were 0.533 and 0.544 were found coexisting in both the variantsBy the means of HPLC, the inner hormone content was measured. The result showed that the dwarfing lines contained less IAA and GA3 in the stem, SV5 had more IAA than SV1O and SV14, while less GA3 on the contrary.