Production of pollenless triploid lily hybrids from Lilium pumilum DC. × ‘Brunello’

Abstract

Embryo rescue was employed to create four pollenless Asiatic triploid lily hybrids, ‘PB1’, ‘PB2’, ‘PB3’ and ‘PB4’, from the cross of Lilium pumilum DC. (2n = 2x = 24) and the Asiatic lily cultivar ‘Brunello’ (2n = 4x = 48). Cytological observation confirmed that all four hybrids were triploid (2n = 3x = 36) and that the progeny and their parents all shared the 3B karyotype. Some abnormal behavior was observed in the triploid hybrids during pollen mother cell meiosis, including chromosome bridges, lagging chromosomes, micronuclei and unequal separation. The hybrids ‘PB1’ and ‘PB2’ had malformed anthers that were pollenless and could not release pollen grains, but the other two hybrids, ‘PB3’ and ‘PB4’, had a few pollen grains in anthers that were almost normal in shape. The stem diameter, leaf index, inner perianth length, outer perianth length and flower diameter of the four hybrids were all intermediate between the respective traits of the parents. However, plant height, stem diameter and flower number per plant were superior in hybrid plants compared to both parents. Flower color, hairs on bud, flower direction and tepal shape showed wide segregation among the hybrids. Hybrid ‘PB2’ was also fragrant. The four triploid hybrids can be used as garden plants directly or as new genetic resources for breeding pollenless lily cultivars.