Effects Of Exogenous Substances On Growth And Sexual Organ Development In The Gametophyte Of Adiantum Reniforme Var. Sinense

The endangered species Adiantum reniforme var. sinense is endemic to Tree Gorge of Yangtze River. The engineering project of Three Gorges Dam and the extensive excavation make the fern habitat destroyed so that the number of this species significantly decreased. Thus, it is necessary to do research on its breeding and conservation biology. The germination and gametophyte development of fern spore were easily effected by environmental factors in nature. A. reniforme var. sinense is the same type fern and it could be effected by the environmental factors as well. The effects on the gametophyte development and sexual organ differentiation were examined by using exogenous substances in order to find out the molecular mechanisms of sexual organ differentiation.In this study, the spores of A. reniforme var. sinense were used as explants, we discussed the influences on the growth and sexual organ development of gametophyte by using different exogenous substance in vitro, including GA3, GA4+7, PP333, ABA, ACC and Ca2+. The main results are as follows:(1) The exogenous substance which made the spore germination rate increaced were GA3, GA4+7, PP333, ABA and ACC. The perfect concentration for the highest spore germination rate were 5.0 mg/L GA4+7,1.0 mg/L PP333 and 1.0 mg/L ACC, which were 27.4%、33.9%、51.6%.The exogenous substace which delayed the germination were GA4+7, PP333 and ABA. However, Ca2+ had no obvious influence on the spore germination rate and germination time.(2) Gibberellic acid(GA3 and GA4+7) could improve the gametophyte growth,3.0mg/L GA3 was best concentration to make gametophyte developed into cordate shaped.2.0-3.0 mg/L PP333 and ABA restrain the gametophyte growth and the development. Especially by 3.0 mg/L PP333,90.6% gametophytes stayed in filaments. In early stadge of gametophytes growth, ACC could not effect in width growth. In later stage of gametophytes growth, ACC could make the gametophyte stay in the filaments. However, more than 90% gametophytes remain filaments status by using 2.0 and 5.0 mg/L ACC. Using 0.2 mg/L Ca2+ was the most remarkable to make the gametophyte grown and developed into cordate shaped.3) Gibberellic acid (GA3 and GA4+7) could induce more meristems and archegonias on gametophyte. Treatment 3.0 mg/L GA3 could induce more archegonia which was 18.2 on one gametaophyte and formation rate of sporophytes was highest. PP333 and 0.5-1.0 mg/L ABA were good at the formation of meristems and 0.5 and 2.0 mg/L ABA were benefical to the formation of archegonias. PP333 and ABA were useless to the formation of sporophytes. ACC treaments make gametophytes develop into bar gametophytes and there were less archegonias on the bar gametophyte. The normal gametophytes had more archegonia and a few sporophytes formation with 1.0 mg/L ACC treatment. Ca2+ took part in the formation of meristems and archegonia,0.2 mg/L Ca2+ would be best to stimulate meristems and archegonia formation on the gametophyte and induce a few sporophytes.