Study On Iron Absorption,Tissue Culture And Gene Transformation Of Malus Pumila Mill

This paper studies iron nutrition of apple (Malus.pumila. Mill.). The results could be discussed as follows: First, iron absorption characteristic of apple rootstock seedlings the Fe insufficient genetype M baccta(L.) Borkh , are studied in nutrient solution under controlled environmental conditions. During 8-14 days growing in media minus Fe or high pH, the seedlings are unable to acidise the rhizosphere and don's increase Fe(II1)-reducing of root obviously. Both p11 and reducing capacity go up and down in 2-3 days rhythm, which means the accumulation and mobilization of apoplasmic iron-pools in roots,and iron deficiency stress enhanced the mobilization in some degree. 25 days cultured in media with low level of iron or high pH induces leaf chlorosis, theplants have smaller seedling and root growth, higher ratio of rootlseedling(fresh weight),lower chlorophyll content and lower Fe(III) reducing capacity. lower iron absorption rate as compared with green ordinary seedlings. Secondly, stem segments with axillary buds of apple rootstock Ma//us xiaojinensis Cheng etJiang (Fe-efficient genetype), M. baccata (L.) Borkh (Fe-inefficient genetype) ,M hupehensis var.Pinyiensis Jing as explants are cultured in tubes. The results indicate that the most appropriat media in culture stage are (MS+l-l.5 mgIL 6-BA /O.1NAA) for Ma//us xiaojinensis Cheng et Jiang 0.8-1.0/0.1 for M baccata (L.) Borkh bud-sprouting and subculture.0.5/0. 1 or 0.5/0.05 for M hupehensis var.Pinyiensis Jing; I /2MS?.5mgIL IBA for M hupehensis var.Pinyiensis Jing rootinng. In the third part, Ferritin gene encoding iron storage protein cloned from the French bean plant, Phaseollus vulgaris L.cv is used to transform the apple cultivars Gala, Fuji through Agrobacterium-mediated transformation method, in order to obtaintransgenic apple cultivars producing high-iron-content fruit. The results indicated that high transformation frequence is decided by both optimal condition for adventitious shoots regeneration of leaf explant (different way of incubation, different length of dark incubation period, different plant growth regulators in media for different genetype in same Genus Malus) and antibiotics concentration and type supplemented in media for the initial selection.Still,many other factors play some roles in transfomation. Transgenic calli obtained are detected by GUS analysis which primerily ascertained the conformity of Ferrition gene in the genome of apple.