| Lily,as an important commercial flower,is very popular in the market.Polyploid breeding can improve lily’s ornamental quality and stress resistance to some extent.In this paper,the somatic polyploidization technique of L.longiflorum ’Qingchun’,the screening of OT hybrid lilies to produce unreduced gametes,the hybridization technique and the chromosome composition analysis of hybrid progeny were studied,providing a certain idea for the improvement of ploidy breeding technology of lilies and the excellent strains obtained laying the foundation for the cultivation of new varieties.The main conclusions were as follows:1.Established the aseptic regeneration system of L.longiflorum ’Qingchun’.optimized the sterilization method of the explant and the cutting method of the cluster bud.The results showed that the secondary sterilization,namely sterilization with sodium hypochlorite solution for a period of time,and re-sterilization after washing with distilled water,could significantly reduce the pollution rate.Besides,different cutting methods had a certain influence on the subculture of the buds.When cluster buds were cut into bud blocks containing one adventitious bud,the multiplication coefficient was 6.90±0.35,which was significantly higher than that of cutting into 2 or 3 indefinite buds.2.The somatic polyploidization technique of L.longiflorum ’Qingchun’ in vitro was studied and the species,concentration and treatment time of mutagens were screened.The results showed that it was more suitable for chromosome doubling after 12 days of preculture;when the treatment concentration of colchicine was 0.1%and the soak time was 36h,the induction rate was the highest,reaching 14.44±5.09%;when the treatment concentration of oryzalin was 0.01%,the soak time was 24h,the induction rate was the highest,reaching 12.22±3.85%;however the toxic effect of oryzalin on L.longiflorum ’Qingchun’ was serious,most scales lost their ability to differentiate after immersion in oryzalin,and the scales were brown and decay were severe,while the damage caused by colchicine treatment to scale differentiation was lighter.In general,the induction effect of colchicine was better than that of oryzalin.3.The polyploidization effect of chromosome doubling in L.longiforum ’Qingchun’ was studied,the results showed that the leaf length,leaf width and leaf thickness of tetraploid plants were significantly larger than diploids,reflecting the greatness of polyploids to some extent;the tetraploid plants were propagated and rooted,and the results showed that it was difficult for the mutant plants to proliferate and root in the early stage,the proliferation coefficient of tetraploid clumped buds in the initial generation was only 2.90±0.03 and the rooting rate of tetraploid was 73.33±3.34%,which were significantly lower than that of diploid plants;with the continuous increase of the number of successive generations,polyploid proliferation ability restored to a certain extent;the proliferation coefficient of tetraploid cluster buds in the second generation increased to 3.7310.07.but it was slower than that of diploid plants(the proliferation coefficient was 6.01±0.32),indicating that the polyploid plants had obvious growth retardation.4.Varieties producing 2n pollen in OT hybrid lilies were screened,and the meiosis period of buds during high temperature period was correlated with 2n pollen production.The results showed that OT26 did not produce 2n pollen at microspore mother cell stage under high temperature,however,when high temperature acted on OT14,OT15,OT23 and OT41 during the fine-line and double-line stages,a certain proportion of 2n pollen was produced,which indicating that the high-temperature period had a certain influence on the production of 2n pollen..5.The hybridization between OT hybrid lilies of different ploidy and oriental lilies was carried out.The results showed that there was a positive correlation between the secretion of stigma and the results of artificial pollination in OT hybrid lilies.The stigma mucus had a certain promoting effect on pollen germination during hybrid pollination;there was a pre-fertilization disorder in the cross between ’Cocossa’ and ’Siberia’,incompatibility occured in stigma mastoid cells,style channel cells,ovule and pollen tube,and the difference between the positive and negative crosses was obvious,what’s more,the pollen tube could not enter the ovule at the time of reciprocal cross;when the OT hybrid lilies were crossed with the oriental lilies,after about 30 days,the partially enlarged ovaries gradually wrinkled and yellowed,indicating that the hybrid embryo had a certain degree of abortion,and the embryo rescue should be carried out in time.6.The chromosome composition of the hybrid progenies of the triploid OT hybrid lily called 4#was analyzed,and the results showed that the types of chromosome numbers of the progeny obtained by hybridization of 4#as the female parent were more abundant(totally 8 types),with chromosome numbers between 24 and 33,than that obtained by hybridization of 4#as male parent.It could be seen that the tolerance of the embryo sac to the changes of chromosome numbers was much stronger.And the number of chromosomes in the progeny tended to be diploid,the proportion of aneuploid was much higher than that of euploid as well.The differentiation of progeny strains obtained from hybridization of 4#was observed and the results showed that the differentiation mode and speed of different strains were correlated with the parental type and the chromosome number of the daughter strains.The strains obtained from the hybridization of 4#and Raizan ’3’ mostly need to re-differentiate after the callus stage,while the other strains could directly differentiate into adventitious buds;as for the differentiation rate,the strains hybridized between 4#and ’Entertainer’ had the fastest differentiation rate;in addition,the strains with the number of chromosomes tending to be triploid had a faster differentiation rate. |
