Inducing Polyploidy Plants Of Oncidium Flexuosum Lodd.with Colchicine

Oncidium flexuosum Lodd is tropical attached-living orchid belongs to Orchidaceae family. It is one of the important cut-flower and potted plants species in the world that has quite a wide prospect in the market. Polyploid breeding of Oncidium flexuosum Lodd. will be helpful to create new varieties, improve the ornamental quality and the value in the market. For breeding and germplasm innovation has great significance. In this paper, Wilson Tropic Breeze’Everglades’ was used to be experimental material and the method of colchicines and plant tissue culture technology induced chromosome doubling of Oncidium flexuosum Lodd. The main results were as following:1.Protocorm of tissue culture seedling were treated with colchicines by soaking, or adding into the medium to induce polypoids.The results showed, the induction rate of being treated with colchicines by soaking is26.67%,which is fore times than which by adding into the medium,compared with colchicines on multiple shoot clumps with soaking method, using colchicines on stem with buds with soaking method could obtain better mutagenic effects, the speed was also quickly, but the poison is larger for materials. So treatment time and concentration should be controlled strictly. It’s good for the material to increase the survival rate by recoverying for a while before experiment.2.This experiment found by preliminary identification, the induced tetraploid plants showed that the speed of growing became slower, Plant stocky, the stem became rougher, leaf shape index became smaller, At the same time color of the leaves became deeper, the number of pores of hypodermis became less and the stomata guard cell is enlargement. The leaf index of diploid is8.25, the leaf index of polyploidy is5.27, the leaf stomata of polyploidy make up46.47%of diploid, the guard cell length of polyploidy make up143.28%of diploid, the guard cell width of polyploidy make up130.60%of diploid.The check results of flow cytometry showed that the relative DNA content of polyploidy is two times than diploid.3.Established the optimization system of chromosome sectioning of Oncidium flexuosum Lodd in vitro. The results showed that the optimal sampling time of root tips was about9:00a.m. The samples pretreated with a solution of0.1%colchicine and0.002mol/L8-hydroxyquinoline at room temperature for4hours, and fixed with the Carnoy’s Fluid solution for12-24h. Then root tips were fixed with the fixative solution hydrolysed with HCl for8min at60℃and stained with modified Carbol fuchsin solution for25min. Then a good effect of chromosome had be distinct. The number of the chromosome is2n=72、4n=144。4.Identification of physiological and biochemical index, polyploids of Oncidium flexuosum Lodd with all of physiological and biochemical indexes were above normal. The chlorophyll-a content of polyploidy make up157.09%of diploid, the chlorophyll-b content of polyploidy make up107.31%of diploid, the total Chlorophyll Contents of polyploidy make up135.85%of diploid.The peroxidase activities of polyploidy make up117.79%of diploid, the catalase activities of polyploidy make up130.36%of diploid.