Aneuploids without bulbils segregated in F1 hybrids derived from triploid Lilium lancifolium and diploid L. leichtlinii crosses.
Lilium leichtlinii (2n=2x=24) is the most commercially cultivated edible lily in Japan, although viral and fungal diseases are severe problems. Triploid L. lancifolium (2n=3x=36), the bulbs of which are also edible, adapts well to the climate in Japan, and feral triploid L. lancifolium plants are often seen along roadsides and in croplands. Thus, triploid L. lancifolium is an important genetic resource for edible lilies, but it develops many bulbils (aerial bulbs) on leaf axils. Bulbil formation is undesirable for edible lilies because bulbils can compete for photosynthate with bulbs, which limits the use of triploid L. lancifolium in commercial production. Edible lily cultivars have been bred by intraspecific crosses within L. leichtlinii, although interspecific hybridization, which increases the level of genetic variation, is the major technique used to breed floricultural lily cultivars. In this study, interspecific-hybrid plants were developed by crossing triploid L. lancifolium and L. leichtlinii, and their characteristics, including bulbil formation ability, were evaluated. The crosses of triploid L. lancifolium × L. leichtlinii developed aneuploid plants, of which the chromosome number ranged from 26 to 34. Bulbil formation ability was continuously distributed in the F1 offspring, although 86% of F1 plants did not develop bulbils, indicating that many aneuploid plants without bulbils are developed by this cross combination. The plants harboring abnormal anthers were segregated in the hybrids. In addition, pollen germination in the F1 hybrids was lower than 20%, and 85% of the hybrids exhibited no pollen germination. However, abnormal anther morphology and low pollen fertility should not be major problems for edible lily production because bulbs are the main commercial output. These results indicate that interspecific hybridization between triploid L. lancifolium and L. leichtlinii has the potential to develop elite edible lily cultivars.