Study on lily introgression breeding using allotriploids as maternal parents in interploid hybridizations

Based on a recent hypothesis, "Five same genomes of endosperm are essential for its development in Lilium", it is expected that allotriploid lily (OTO) can be hybridized with diploid Oriental lily (OO) for introgression breeding in Lilium L.. To test the hypothesis, OTO lilies, 'Belladonna', 'Candy Club' and 'Travatore', were used as the maternal parents and crossed with two diploid OO cultivars, 'Siberia' and 'Sorbonne', and the species L. regale Wilson (TT). Results showed that capsules of all OTO × OO hybridizations developed well and 0.8~3.3 viable seedlings per ovary were obtained through normal pollination and embryo rescue; however, all OTO × TT crosses failed. Genomic in situ hybridization showed that the progenies of the OTO × OO hybridizations were aneuploid and a variable number of T-genome chromosomes were introduced into the progenies through the allotriploid lilies. The present results not only demonstrate that allotriploid OTO lilies, although male sterile, can be used as maternal parents to produce aneuploid progenies, but also strongly support the new hypothesis in lily breeding.