Organogenesis Characteristics And Genetic Stability Of Apple Shoot Explants In Vitro After Subcultured For Years

For figure out the optimal life span of germplasm preserved in vitro, it is necessary to understand whether its propagating ability changes or not after subcultured for years. The shoot multiplication ability, adventitious root regeneration rate from shoots, adventitious bud regeneration rate and DNA variation from leaves of'Fuji','Golden Delicious','Jonagold'and'Gala'apple in vitro shoot explants were studied. .The main results are as follows:1.The shoot multiplication ability of'Fuji','Golden Delicious'and'Jonagold', the adventitious root regeneration rate of'Gala', and the adventitious bud regeneration rate from leaves of'Golden Delicious','Fuji', and'Gala'during the first four years after inoculation from field, that was at the stage of subculture from 24 to 40 times. With the increasing of the subculture times, the abilities for the given cultivars could increase and keep at a higher level stably. The apple explants repeatedly subcultured in vitro for years (25 years for'Fuji', 19 years for'Golden Delicious'and'Jonagold', and 10 years for'Gala') could remain their organogenesis characteristics.2. With the increasing of the subculture times, the content of ABA and ZR decreased in the seeding cultivation. The changes reported bud initiation and adventitious root. The content of GA was high in subculture early times. With the increasing of the subculture times, the ratio of IAA/ZR stabilized higher level. So the apple subcultured in vitro for years could remain their organogenesis characteristics.3. The transplant survival rate of'Fuji','Golden Delicious','Jonagold'and'Gala'apple in vitro shoot explants was higher. At the early stage after transplanting, height and leaves the areas were no significant differences. The leaf number was less of lower subculture times apple shoot explants. The morphologies in the field no differences at the later stage after transplanting. The result showed that the apple explants repeatedly subcultured in vitro for years could remain their genetic stability.4. Content of nuclear DNA for apple cultivars including 9 diploid and 8 triploid was measured by flow cytometry. The average nuclear DNA content of diploid cultivars was 2. 27 pg and that of triploid cultivars was 3. 13 pg, which indicated that variation of nuclear DNA content between diploid and triploid was significant.5. By examining their root tip chromosome numbers,'Fuji','Golden Delicious'and'Gala'were diploid ,'Jonagold'was triploid. Not been observed the chromosome number and morphology of variation.6.'Jonagold','Gold Delicious'and'Fuji'were studied to AFLP analysis. 4 primers with high polymorphism and powerful distinctiveness from 10 primer combinations produced 430 fragments. The primers were E-AAC/M-GAC,E-ATC/M-CCG,E-CTA/M-AGG,E-TAA/M-CTG. There was no difference of different subculture times.