| Experiments of producting polyploid were made with cultured 3 diploid varieties(Bio, 62) of Averrhoa carambola Linn by combinning plant tissue culture with chromosome engineering.In this study ,the system of plant regeneration in vitro from adult buds of 3 diploid varities was established.on the base of it ,Induction of tetraploid plantlets were obtained by the treatment of colchicines and the technology on chromosome doubling by colchicines treatment was also proved.moreover,Triploid plantlets of Bn were obtained by cultureing the endosperms of seeds.The rule of callus induction of endosperms.buds differentiation from callus.vegetative propagation.rooting and growing successfully in soil was systematically researched.The result indicated that:It was fundmental to the experiments of rapid propagation and breeding by using chromosome engineering that the system of plant regeneration in vitro from the adult buds of the three kind diploid varieties was established.lt is decisive to the system of plant regeneration in vitro was established that the kind of hormones and the ratio of hormones make effect on explants.The result indicated that it is strict in the kind of cytokinin,the order of the effection of cytokinin is ZT,BA,KT.as for the kind of auxin It looks as if it isn't strict.The optimal medium is MS supplemented with BAO.SmgL'1 NAA0.2mgL"' and GA0.2mgL"',proliferation index was as high as 3.7.The chromosome ploidy of plantlets in vitro was proved and the number of chromosome was 22(2n=2x=22).0n what has already been achieved,some methods were used and compared for inducting tetraploid plantlets of Averrhoa carambola L The tetraploid plantlets were obtained by immersing buds in various solution of colchicines,inoculating buds in the medium supplemented with colchicines and dripping buds in various solution of colchicines on the condition of tissue culture and so on.These methods were compared .The way of immersing buds was better,the inductive frequency was 36.7%,the effection of the others was worse.as to the three kind varieties,The effection of Bn of inducing tetraploids was better and the induction frequency was higher(36.7%).Best result for inducing tetraploids was obtained when the plantlets of the three kind varieties were soaked in colchicines solution with the concentration 0.2% for 25h and the highest frequency was 36.7%.When the explants were cultured in the medium supplemented with colchicines,the best result for 810,82 was cultured in the medium supplemented with the concentration 0.2% for 20d,the best effection for Bn was the concentration 0.1 % for 20d.The data of cytological observation showed that the tetraploids wereobtained,The chromosome number of mutation plants was 44(2n=4x=44).When endosperm was inoculated on MS medium supplemented with 2,4-D2.0mgL"' and BA0.2mgL"',the highest rate of callus induction was obtained and the frequency was 93.5%.The callus looked light-white,compact.when the endosperm callus was transferred to the differentiation medium MS+ZT3.0mgL"'+NAA0.2mgL"1,The callus change greenish,compact and capable of redifferentiation,buds were regenerated from 73.3% callus.The optimal medium of multiplication in vitro of endosperms plants was MS supplemented with ZT2.0-2.5mgL"1 and NAA0.05mgL~'.The large number of triploids were obtained in a short time.The chromosome ploidy of the endosperm-derived plantlets was proved triploid and the number of chromosome was 33(2n=3x=33).Simultaneously,there also have some aneuploids and multiploids .Up to now we have obtained 1000 triploid plantlets.The way of the endosperm-derived triploid was economical,high-speed and comvenient.In the process of polyploid multiplication,the polyploid plantlets were cultured on the optimal medium MS+ZT2.0-2.5mgL"'+NAA0.05mgL"1,proliferation index was 6.2-6.5 and the large numbers of tetraploids were obtained in a brief space of time.At the same time,It is important to the propagation of that we add ZT to medium.Although the kind of cytokinin is rigorous on the condition of tissue culture ofAver...
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