A Study Of Vitrification On Chinese Onion(Allium Fistulosum L.) In Vitro And Polyploid Induction

Chinese onion(Allium fistulosum L.) was cultured in vitro to investigate the morphological,physiological and biochemical characteristics of vitrification. Forming factors and reversion on vitreous plantlets were also observed. At the same time, the effect of colchicine treatment on the callus induction was studied in this paper. The main results can be summarized as follows: The appearance of vitreous plantlets was different from normal plantlets. Vitreous plantlets had more water, fewer total chlorophall,chlorophyll a and b. In vitreous plantlets, peroxidase(POD) activity increased, content of soluble protein decreased. The result of protein electrophoresis indicated that there were some differences between vitreous plantlets and normal plantlets. Vitreous plantlets had most basic bands like normal plantlets. Moreover, it added two bands of higher molecular weight and one band which molecular weight is about 25KD, but lost two bands of smaller molecular weight. The bands of peroxidase(POD) isozymes showed vitrous plantlets lost three bands such as Rf0.245, Rf0.309, Rf0.382; but added one band of Rf0.200, and the activity of Rf0.136 was increased. Isozyme and protein are the production of gene expression. The change of vitreous plantlets in protein level indicated that the occurance of vitrification was in correlation with gene expression. From the study of forming factors on vitrification, vitrificational occurance had some ralation to growth environment. The percentage of vitrification was affected by mang factors, including materials inoculated, BA concentration, agar concentration, sugar concentration, seal materials, light intensity and temperature. It showed too high humidity, high BA concentration and faint light intensity easily induced the occurance of vitreous buds. With the continuous generations increasing, the vitrificational phenomenon would aggravate. Reversion of vitrification showed vitreous plantlets' genome might no change radically.Culture conditions of effective prevention for vitrification: medium for shoot regeneration from callus was MS+BA2.0mg/L+agar0.8%+sugar3%; in subculture stage, BA concentration was 1.0mg/L and 2.0mg/L in turns; sealed using the parafilm with some bores, inoculated after fresh medium was placed three days, under a light intensity of 3000lx or higher.Studied the induction effect of colchicine with different concentration and treatment time on callus. Along with treat concention and time increasing, the death rate grew up significantly. Too high treat concention might lead the rate of polyploid cell was decreased. 0.06% colchicines with 72h treatment was effective on polyploidy induction. The inducing rate was high, and callus was harmed gently. Obtained some variation plantlets. Compared with the diploidy, the morphology and leaves stoma had changed, its leaves became thicker , more coarse , and leaves stoma became significantly bigger.