Changes Of Physiological And Biochemical & Expression Of Cold-resistant Relevan Genes On Three Medicago Forages During Different Phonological Period

In this experiment, Medicago ruthenica (L) Sojak.cv.’Zhilixing’, Medicago sativa cv.Aohan and Medicago falcate L. were selected as the objects to study their physiological and biochemical changes in different phenological period, and change rules of expression quantity of cold-resistant genes MRHLH, MRPP2C and MRHSP70. Besides, the relationship between expression difference and cold-resistant response of three genes in three forages of Medicago was analyzed, and the correlation between chill-proof gene expression of three forages under low-temperature stress and their physiological change was explored. The research resulted laid a foundation for deeply studying cold-resistant mechanism and cold-resistant gene application of Medicago period. Main research results were as follows:1. Three cold-resistant genes could expressed at the root and leaf of three forages. MRPP2C showed the highest expression level, followed by MRHSP70. The expression level of MRHLH-was lowest.2. In overwintering period, the expression quantity of MRHLH and MRHSP70 increased significantly with temperature reduction, while the expression quantity of MRPP2C has no obvious change. But the expression quantity of three genes also significantly improved in reproductive stage of Medicago sativa cv.Aohan and Medicago falcate L.3. The content of soluble sugar, soluble protein, free proline, SOD and POD at the root of three forages increased significantly in overwintering period. However, compared with Medicago sativa cv.Aohan and Medicago falcate L., free proline accumulated at the root of Medicago ruthenica ahead of time, and improved the activity of SOD and POD.4. Within overwintering period, the expression quantity of MRHLH is significantly related to the activity of SOD and POD. MRPP2C and MRHSP70 presented extremely significant positive correlation.