Study On Light-regulated Development And Biological Characters Of Sorghum Mutant Induced By Space Condition

Seeds of pure breeding sorghum (CK) were treated by Chinese Reversal Man-made Satellite in 1996.A dwarf and earliness mutant (SP) was obtained by selection from the returned seeds after many years. We presumed that there were homologous cryptochromes like CRY1 and CRY2 in the mutant , resulting in the characters of short setm and earliness .So we devised the three experiments to observe the appearance in physiology and morphology , and then investigate the action of photoreceptors in physiology. The experiment on callus induction of sorghum mutant was also made, in order to prepare for gene transferring next step.Our work has comprised the following three aspects:First, we found that there are many difference as follows (1)the maturing period of SP was earlier and the height of SP plant was shorter than the control.(2)The ear length increased.The leaves of spare shorter, narrower and thicker. Their leaf area deceased.(3)The length of ear axis for mutant increased, and the lenth of internode reduced.(4)There were many difference on the morphology characaters of spike. The genetic characters of mutant are stable.Secondly, the photoperiod experiment was carried out. Our experiment used sorghum mutants induced by space condition(SP) .We focus on expression in photoperiod-sensitivity of the mutant.Comparing the SP with the control(CK) under different photoperiod, we didn't find the distinct difference among the SP and CK .Thirdly, we investigated sorghum photosensitivity under five different kind of light, include FRL(far-red light), RL(red light), BL(blue light), WL(white light) and D(dark), at the same time, added a certain concentration of GA3. The result showed that photosensitivity of the different materials varied greatly.The different lights profoundly affects phototropic behavior of sorghum mutant, especially affects the seedling characters on middle plumuler axis, plumule sheath, root and leaf. The effects of the experiment showed that the middle plumuler axis and plumule sheath were most sensitive to blue light, this maybe strongly depends on cryptochrome system triggered by lights. We suggested that there might be mutational gene resulting in the sensitivity to the restraining function of blue-light.Finally,we carried out the experiment on callus induction of sorghum mutant .This was the first time to do such research work.Sorghum seeds were cultured on the medium containing Murashige-Skoog(MS) mineral salts supplemented with 2, 4-D and KT. The study was carried out on the influences of the culture medium on the callus induction and culture by using different parts of sorghum as experimental material. This paper deals with systematic studies on initiation , maintenance and plant regeneration of callus . Good callus induction was obtained from the cultures of four types of explants including seed, mature embryo, young embryo, and shoot tip .Among the factors which can influence the callus for formation and plant regeneration of sorghum mutants, we focused on the the most crucial elements 2, 4-D and KT in MS medium.We found the suitable contion for the callus formation and also the plant regeneration afterwards.