Study On Cross-compatibility And Embryology Of Interspecific Hybridization In Iris

The cross-compatibilities were studied after common pollination by using Iris lactea Pall.Var. chinensis Koidz.,Ⅰ.sanguinea Hormen., I.ensata Thumb., I.pseudacorus L.,Ⅰ.dichotoma Pall., Belamcanda chinensis. Leman. as materials. Pollen tube behaviors and embryonic development of reciprocal crosses between I.lactea and I.sanguinea,Ⅰ.ensata andⅠ.pseudacorus,Ⅰ.dichotoma and B. chinensis were studied by means fluorescence microscopy and paraffin sections in order to provide a basis for the cross breeding of Iris. Pollination methods and embryo culture conditions of different combinations were investigated for overcoming combination barriers between interspecific hybridization. The main results were as followed:1,Pollen germination rate was arrang from 50% to 97% among 10 Iris species exceptⅠ. germanica., which pollen germination rate was 0.2,pollen germination rate decreased ofⅠ.ensata after two months storage. The optimum storage treatments were dry pollen grains with CaCl2 or silica gel. The best way to srote pollen grains at 4℃was pollen grains with n-amyl acetate.-20℃was the best temperature for storing pollen grains, Pollen germination rate was above 20% even just in centrifugal tube.3,The highest cross-compatibility was observed inⅠ.ruthenica var. nana MaximxⅠ.uniflora Pall. And I.dichotona xB.chinensis. The rate of capsule setting reached to 90.9% and 87.9%, and the rate of embryo was arrival at 54.2% and 54.3%, separately, while the lowest was in the reciprocal crosses ofⅠ.sanguimea×Ⅰ.lactea.4,The rate of capsule setting and embryo was distinguished in the reciprocal crosses of different combination. The capsule setting rate and embryos rate ofⅠ.ruthenica×Ⅰ.uniflora was twice times higher thanⅠ.uniflora×Ⅰ.ruthenica, which reached to 83.0% and 21.85%. The capsule setting rate was similar between the reciprocal crosses ofⅠ.pseudacorus and I.ensata, but embryo rate ofⅠI.pseudacorus×Ⅰ.ensata was 21.48%, and 83.0% in I.ensata×I.pseudacorus.5,The growth ways were similar among self pollination ofⅠ.ensata,Ⅰ.pseadacorus,Ⅰ.dichotoma and B.chinensis. The ratio of length and width were similar, too. The ratio tendency of lenth and width was increased first then decreased, following by steadied. The stable periods ofⅠ.ensata andⅠ.pseudacorus self pollination were 18d and 24d after pollination, while self pollination ofⅠ.dichotoma and B.chinensis were 21d both.6,The ratio of lenth and width of the reciprocal crosses ofⅠ.ensata andⅠ.pseudacorus, I.dichotoma and B.chinensis were different. The variation tendency of reciprocal crosses betweenⅠ.ensata and I.pseudacorus was small. The variation tendency ofⅠ.dichotoma×B. chinensis was similar with self pollination of I.dichotoma.7,No capsules were obtained from reciprocal crosses between Ilactea andⅠ.sanguinea, which inferred cross-inconpatibitily between them. The ovaries of I.lacrea fell of after 3d of pollination, and ovaries ofⅠ.sanguinea×Ⅰ.lactea were swelled in 5d after pollination,then withered. 8,The pollen rube behaviors of inter-specific pollination showed that:1) no germination of male parent; 2) pollen tube grew slowly or stagmated on the stigma of female parent; 3) callose responses at stigmas, pollen tubes and pollen tube channels and ovaries; 4) shriveled pollen grains on the stigmas after pollination; 5) pollen tube abnormal phenomenons: transverse and reverse direction growth or bending on the midway.9,Embryology development situation of Iris interspecific hybridization indicated that: Different combination of hybrid embryos were disintegrated at different periods. The division of primary endosperm nucleus took place immediately after fertilization. The first division of the zygote took place after days of dormancy period. The embryo ofⅠ.ensata×Ⅰ.pseudacorus disintegrated at the 9th day, while some embryos of anti-cross grew up, some other disintegrated after 3d pollination. There is little barriers inⅠ.dichotoma×B.chinensis embryo development. The embryos of I.dichotoma×B.chinensis disintegrated at the period of scutellum-shaped embryo.10,The optimum pollination method for Llactea×Ⅰ.Lsanguinea was 0.1%BA treatment before pollination, capsule setting rate and embryo rate reached to 10% and 16.67%, respectively, while the benefit way forⅠ.sanguiea×Ⅰ.lactea was pollination in advance, fruiting rate was arrival at 15%and embryo rate was 25.70%, respectively.11,The suitable way for embryo rescue culture was ovules with placenta after removing the ovary wall.The ovules were not suitable as explants, withered after inoculation.Though the ovules with placenta ofⅠ. ensata×Ⅰ.pseudacorus swelled after inoculation, at the center of ovule was full of fluid.