Study On Genomic Variation Of New Cultivars Selected From Distant Hybridization In Lilium With GISH

Lily is an important bulb flower belonging to genus Lilium of Liliaceae.It plays an important role in China flower industry.There are many wild species of Lilium in China,but lily breeding lags far behind other countries.We have to import a large number of bulbs from Netherlands to satisfy the domestic needs.Therefore, it’s an important task for lily breeders to cultivate new varieties with independent intellectual property rights.Most of the Lilium cultivars are from intrasection crosses and classified into four groups:Asiatic, Longiflorum, Oriental and Trumpet.The cultivars resulting from crosses between these different groups have been released because they combine horticultural traits of different lily groups, and hybridization between different groups become one of the one of the main trends in Lilium breeding.In the present study, we chose19new cultivars bred by hybridization between different lily groups:’Brindisi’、’Courier’、’Pavia’、’Advantage’、’Mestre’’Mombasa’、’Pirandello’、’Serrada’、’White Triumph’、’Chiara’、’Santa Rosa’、’Terni’、’Vendella’、’Red Dutch’、’Belladonna’、’Candy Club’、’Cocossa’、’Ovatie’and’Travatore’,used genomic in situ hybridization to examine the genomic variation of to determine how the cultivars arose, in order to avoid blindness in Lilium breeding.The results of GISH show that:1These cultivars were true LA, LO, or OT cultivars, originating from crosses between different groups, as claimed by the lily breeders.2Two of the cultivars are diploid (2n=2x=24), selected from F1OT hybrids,16allotriploid (2n=3x=36),mainly from2n gametes and less possibly from diploid x amphidiploid crosses;and one cultivar is allotetraploid with three L-genomes and one O-genome.3There are different level of chromosomal rearrangements in different cultivars.Based on the results, we conclude that allotriploid breeding is one of the future trends for new cultivars in Lilium, and that most of the allotriploid lily cultivars originate from2n gametes produced by F1distant hybrids.There are important stages to be taken into account when breeding allotriploid lily cultivars.F1hybrids between different groups have to be produced by cut style pollination and ovule culture, then, allotriploid progenies could be obtained from backcrosses using F1hybrids as female. If F1hybrids are totally male and female sterile, amphidiploids must be induced to restore fertility of the F1hybrid by chromosome doubling. The allotriploid lilies can then obtained by diploid x amphidiploid crosses.