Study On Techniques Of Pollen Chromosome Doubling Of Asiatic Hybrid

Lily polyploidy breeding is the main way for germplasm innovation. The induction of polyploidy mainly through inducing somatic cell without division and cell chromosome unreduced. The 2n gametes technology is an effective way to quickly obtain triploid, especially favorable for the plants of many years to bloom. In this study, using flower buds of Asiatic Hybrid Avignon as materials, the meiosis processes of pollen mother cells were observed. The research on the technology using colchicines to manually induce 2n pollen was described. This paper, and would establish a base for the triploids breeding by pollinating to normal Asian Lily with 2n pollen. The results are as follows:(1) In Shenyang, PMCs started to meiosis about May 20 and lasted approximately 7 days in Asiatic Hybrid. Through study on the meiosis course of Avignon pollen mother cells, and the result shows:there is some correspondence between flower buds length and PMC developmental periods. Therefore,we can easily identify the microsporocyte meiosis stage by its buds length, and determine the pollen chromosome doubling time correspondingly.(2) The result of induce doubling pollen chromosome with different treatment methods shows that, compared with cotton wrap, injection is more suitable to such sensitive organizations like lily buds. The result of induce doubling pollen chromosome by different treatment period, different concentration of colchicines and different treatment times shows that, the frequency of 2n pollen between different treatment combination had a significant difference in 2n pollen induced of Avignon. The highest average percentage of 2n pollen was 40.1% by treating flowers for 48h with 0.1% colchicine in pachytene.(3) In optical microscopy, the normal pollen grains of Avignon are ellipsoid or long ellipsoid, uniform size,the average length of shaft diameter are 87.3μm and 56.9μm; the volume of the 2n pollen grains obtained after treatment increase significantly, color become darker,mostly spherical, and not have uniform size,the average length of shaft diameter are 110.2μm and 101.7μm.(4) In optical microscopy, the volume of large pollen obtained from the experiment is larger than the normal one. The DNA content of large pollen grains induced by colchicine is two times of haploidic pollen by using LSCM. Evidently, the large size pollen we got is unreduced diploid pollen. (5) Determination of pollen germination rate shows that,the germination rate of normal-sized pollen grains is 38.6%, and the germination rate of 2n pollen induced by colchicines is 14.8%. Compare with normal-sized pollen, the germination capacity of 2n pollen is significantly lower and the growth rate is relative slower. The 2n pollen doesn't have strong competitiveness in hybrid breeding.