Study On Selection Of Mutant For Aluminium Tolerance Of Medicago Sativa L.

In order to adapting the development of stockbreeding in the south China, alfalfa has already been cultivated in the south area. But, the soil acidity is common in the area, and the acid conditions can activate aluminum in the soil which brings serious toxicity to alfalfa, and restrict alfalfa to be widely cultivated in the area. Long-term's practices have been proved that it is the finest choice to breed alfalfa for aluminum tolerance to solve the problem. The results of many studies indicated that the strong Al-tolerant germplasms was lack in the genus of Medicago, and it was difficult to breed Al-tolerant varieties of alfalfa through traditional breeding approaches. Therefore, to use modern biotechnology to transfer Al-tolerant genes or start-up silence of Al-tolerant genes is the method which has a good chance to gain Al-tolerant alfalfa germplasms. Basing on previous achievements, this study attempts to select Al-tolerant mutations from the single-cell of alfalfa in tissue culture, which will provide a new approach for the breeding of alfalfa to Al-tolerant.In this study, the regeneration system was established using alfalfa "SW -1 "which was breed by our school. The leaves of alfalfa "SW -1" planted in the farm of Southwest Argriculture University were used as explants, and the experiment for selection of callus' culture medium was conducted. The result was shown that there was higher induction rate in the mediums "F" (SH+ 2,4-D5mg/L +KT1mg/L + K₂SO₄4.35g/L + inose100mg/L + proline 1000mg/L ) and "G" (BMS+2, 4-D5mg/L +KT3mg/L +BA0.2mg/L +hydrolyze lactoprotein 1000mg/L) , which were 40.8% and 41.2% respectively. The callus from "F" and "G" was transferred into six kinds of different differentiating mediums, the results indicated that the rate of differentiation was highest in the medium"F₆"(MS0), which reached to 53.3%. The rhizogenic medium "Ci"(l/2MS +sucrose 15g/l) was selected, and the rate of rhizogenesis was highest, which reached to 42.3%. The suspension culture system for alfalfa was probed into in this study. The callus cultured twenty days was used to suspension culture in the "F" liquid medium, the concentration of suspension cell grew faster betweenlOth to 20th days, and the cell concentration reached the highest point on the 22th day in which was 6.4× 10⁵ cells /ml during 25 days' culture. The concentration of suspension cell under four different concentrations of inose (0, 500, 1000, 1500mg/L) was measured, and the 1000mg/L of inose was shown the best concentration for suspension culture. In the fourth subculture, the proportion of live cell reached highest point...