D. Koleva, Ts. Ganeva and M. Stefanova
Sofia University “St. Kliment Ohridski”, Faculty of Biology, BG - 1164 Sofia, Bulgaria
Koleva, D., Ts. Ganeva and M. Stefanova, 2013. Effect of ABA pretreatment on chloroplasts structure in Hypericum rumeliacum Boiss. plants subjected to cryopreservation. Bulg. J. Agric. Sci., Supplement 2, 19: 18–21
Chloroplast ultrastructure in mature leaves’ cells of in vitro cultured Hypericum rumeliacum Boiss. plants regenerated from cryopreserved shoot tips pretreated with abscisic acid (ABA) for 3, 7 and 10 days periods respectively was analyzed by transmission electron microscopy (TEM). The chloroplasts in the control-unfrozen plants were lenticular with well-developed peristromium and thylakoids. The chloroplasts in regenerants passed 3-day period of pretreatment with ABA were structured almost the same to the control ones while in regenerated after 7 day pretreatment plants, reduced volume of the thylakoids was observed. In 10 day pretreated regenerants TEM revealed round shaped chloroplasts and both grana and stromal thylakoids were destroyed. The structural analysis of the plastid apparatus in regrown H. rumeliacum plants pointed out the 3-day ABA-pretreatment as the most efficient for cryopreservation on sub-cellular level of organization.