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

In this experiment,interspecific hybridization was carried out using Lilium lancifolium, L.davidii and Asian hybrids cv.'Pollyanna' as female parent,and wild lilies,Oriental hybrids cv.'Sorbonne'and Longiflorum hybrids cv.'Lorina' as male parent.Cross-compatibility, pollination methods and embryo culture conditions of different combinations were studied,at the same time,pollen tube growth and embryonic development of cross combinations were observed by means of fluorescence microscopy and paraffin sections in order to provide a basis for the cross breeding of lily.The main results were as follows:1,The highest pollen germination rate was 98.27%in L.leichtlinii var.maximowiczii among 10 lilies,and the lowest pollen germination rate was 15.55%in L.lancifolium.Pollen germination rate of wild lilies was generally higher than cultivars.The pollen germination rate decreased by 25%～40%after 15d stored at arid frozen(4℃) condition.2,Using L.lancifolium as female parent,the cross-compatibility in 'L.lancifolium×L. leichtlinii var.maximowiczii' was the highest,while the rate of swelling capsules and rate of embryos reached 90.0%and 45.46%,separately,followed by 'L.lancifolium×L.amabile', the rate of swelling capsules and rate of embryos reached 85.0%and 25.96%,separately,and 'L.lancifolium×Sorbonne' and 'L.lancifolium×Lorina' were the lowest(0.0%).Seven combinations obtained fruits and six combinations obtained embryos among nine combinations.Five combinations obtained F₁ generation seedlings through embryo culture. The cross-compatibility was low using L.lancifolium as male parent.3,The cross-compatibility in 'L.davidii×L.concolor var.megalanthum' was the highest,while the rate of swelling capsules and rate of embryos reached 83.0%and 21.85%, separately,followed by 'L.davidii×Pollyanna',the rate of swelling capsules and rate of embryos reached 80.0%and 13.78%,separately,and 'L.davidii×Sorbonne' and 'L.davidii×Lorina' were the lowest(0.0%).Five combinations obtained fruits and four combinations obtained embryos among eight combinations.Three combinations obtained F₁ generation seedlings through embryo culture.4,The cross-compatibility in 'Pollyanna×L.leichtlinii var.maximowiczii' was the highest,while the rate of swelling capsules and rate of embryos reached 83.0%and 5.98%, separately,followed by 'Pollyanna×L.amabile',the rate of swelling capsules and rate of embryos reached 80.0%and 1.25%,separately,and 'Pollyanna×Sorbonne' and 'Pollyanna×Lorina' were the lowest(0.0%).Five combinations obtained fruits and four combinations obtained embryos among eight combinations.There combinations obtained F₁ generation seedlings through embryo culture. 5,Using the same male parent,the rate of swelling capsules and rate of embryos was the highest using L.lancifolium as female parent,followed by L.davidii and using Pollyanna as female parent was the lowest.As male parent,L.leichtlinii vat.maximowiczii,L.amabile,L. concolor var.megalanthum,L.davidii and Pollyanna were better than the other five lilies which did not obtained future generations.6,The compatible combinations using L.lancifolium as female parent was better using stigma pollination.Cut-style pollination could overcome cross-incompatibility of 'L. lancifolium×L.concolor var.buschianum','L.lancifolium×L.concolor var.megalanthum' and 'L.lancifolium×L.cernuum'.The combinations using L.davidii as female parent was better using stigma pollination while the combinations using Pollyanna as female parent was better using cut-style pollination.There were no significant effects on the rate of swelling capsules using pollen culture solution,however the effects on rate of embryos was depending on cross combinations and pollination methods.7,Embryo rescue culture was an effective mean of obtaining F₁ generation seedlings. 70%alcohol for 1 minute was the best disinfection method for capsules without dehiscence. The rate of embryo germination without seed coat and endosperm was higher 60%～70%than that with seed coat and endosperm,and germinated 17～22 days earlier.40～50d was the best age for the immature embryos to culture in vitro.The best medium for embryos germination was MS+NAA0.01 mg·L^-1+6-BA0.1～0.5 mg·L^-1.There was positive correlation between germinating rate and percentage of seeds with embryo.8,Most of the pollen germinated on the stigma after 4h of interspecific hybridization pollination.The pollen tube of compatible combinations reached the base of style and arrived at the ovule after 48～96h of pollination.The pollen tube of incompatible combinations stopped growing after 48～72h of pollination and finally penetrated into 1/10～1/5 of style. Pre-fertilization barriers mainly took place during pollen tube growth though the style.9,There were five periods in the hybrid embryo development of lily:zygote embryo, original embryo,pear-shaped embryo,scutellum-shaped embryo,mature embryo.The division of primary endosperm nucleus took place immediately after fertilization.The first division of the zygote took place after 5d of dormancy period.Every period of original embryo,pear-shaped embryo and scutellum-shaped embryo persisted about 10d and the embryo completely mellowed after 50d of pollination.Crossing barriers mainly took place during fertilization and cellularization of endosperm.