| Garlic (Allium sativum L.) is one of the important vegetables crops. But variety has been aged and degenerated severely for long time because of asexually propagation and lack of effective breeding route. It has been found that there is high rate of somaclonal variation during tissues culture. Therefore, it is especially meanful to study and utilize somaclonal variation to improve the state of garlic variety.In this study, 5 garlic varieties of different eco-type were used to investigate the law of somaclonal variation in different ways of in vitro culture and the screen of salt tolerant and herbicide tolerant variation lines. The law of somaclonal variation was mainly investigated in the routes of bud regenerated and callus culture. The hereinafter results were obtained.The somaclonal variation of garlic mainly occurred during callus induction and multiplication. Chromosome variation was used as the index to judge if there was somaclonal variation in regenerated plants directly from bud induction and at different stage of callus culture. There was almost no somaclonal variation been found in the bud regeneration route but high somaclonal variation at different stage of callus culture and plant regenerating from callus. This variation was increased and accumulated as the elongation of callus culture duration.The percentage of diploid cells in callus of 5 varieties, Gailiang, Jintang Early, Pengxian Late, Cangshan and European 01, was only 66.7%> 60.0%> 56.7%> 53.3% and 63.3%, respectively. The variation occurred in different degree when different explants, clove base, clove and leaf blade of cv. Gailiang and Cangshan, was used.Garlic's somaclonal variation was found not uniform. The frequency of somaclonal variation occurred was not the same with different variety and was not the same with different type of explants if the variety was the same too. The percentage of diploid cell in the callus derived from explants of clove base, clove and leaf blade of Gailiang, was 66.7%, 46.7% and 43.3%,respectively. This tread was found in cv. Cangshan too. The aspect of variation was found different too. There were euploid as tetraploid, hypoploid and hyperploid in chromosome number variation; chromosome fragment, stickiness, cross and twine among chromosomes and chromosome bridge and so on in chromosome frame variation.The somaclonal variation appeared not only in chromosome, but also in isoenzyme bands of gliadin and the plant morphology. The morphological variation in tube plant appeared in leaf color, leaf thickness, leaf wideness, pseudostem diameter and length, bulb size, root number and length, and plant growth.The somaclonal variation of garlic was affected by the in vitro culture condition and environment. The proportion and concentration of different hormone in medium during callus induction affected the percentage of diploid cell in callus by 43.3% to 63.3%. The percentage of diploid cell in callus was higher in MS medium (36.7%) than that in LS medium (30.0%) and 65 medium (16.7%) during callus multiplication. The percentage of diploid cell in callus descreased as the callus culture times increased. It was 53.3% and 3.3% hi the callus cultured 3 times and 12 times, respectively. The percentage of diploid cell in callus decreased as the culture room temperature increased. The condition of tissue culture had bigger effect on callus differentiation too.According to the principle of adaptability, two screen systems step-to-step for salt (NaCl) tolerant variation line selection was established in this study. Started from 0.1% NaCl and ranging to 1.5% NaCl in the culture medium, the callus was cultured on each medium contained NaCl for 4 weeks in one system and 8 weeks in another system. The tolerant callus which grew well was transferred to the next higher salt medium for continuous culture and selection until it could not grow. By this method, five salt tolerant cell-lines from cv. Gailiang, Jintang Early, Penxian Late, Cangshan and Europe 01 were obtained. The stability test showed that this salt-t... |
PDF Full Text Request