Application of Four Pollination Techniques and of Hormone Treatment for Bypassing Interspecific Crossing Barriers in Lilium L.

Abstract

Crosses between genotypes of the 3 commercially important groups of lilies, i.e. Lilium longiflorum Thunb., the Asiatic hybrids and the Oriental hybrids, are hampered by interspecific crossing barriers. Several methods have been developed to bypass pre-fertilization barriers or post-fertilization barriers in lily, e.g. the cut-style method and embryo rescue techniques. Five techniques were studied comparatively for their capacity to bypass barriers between different types of lilies: the grafted-ovary method, placental pollination, warm-water treatment, the mentor pollen technique and hormone treatment. For the grafted-ovary method, a compatible pollinated pistil was grafted one day after pollination on the ovary of another species. It appeared that the pollen tubes were not able to penetrate from one ovary into another ovary. After placental pollination, no embryo germination was found, even not when pre-pollinated styles were placed near the ovules. After a warm-water treatment (6 minutes of 50 0C) of pistils, many seeds were harvested of self-pollinated flowers of L. longiflorum. However, interspecific crossing barriers could not be bypassed. The percentage of ovules with pollen tube penetration did not change by mixing pollen with radiated mentor pollen. It appeared that the mentor pollen were able to penetrate the ovules. After treating ovaries with 0.1% BAP, on average 6 embryos per flower of the cross L. longiflorum 'Gelria' x Asiatic hybrid 'Mont Blanc' could be rescued when ovule culture was started around 40 days after pollination.

Interspecific Crossing between Lilium hansonii Leichtlin and L. brownii var. colchesteri for the Breeding of New Lily Cultivars

“…In such cases, crosses may not produce any seeds, which led scientists to attempt various methods to solve the problem. Early studies were focused on the identification of proper methods to overcome pollination problems in intra-or interspecific crosses [21,32]. Such methods include the application of growth regulators, pollination after heating the style, cut-style pollination, and pollination with a pollen mixture [32].…”

“…Many early cultivars of interspecific hybrids of L. × marhan and L. × dalhasonii were bred a long time ago in Europe by lily enthusiasts [19,20]. After developing various pollination and embryo rescue methods [21], intersectional crosses of L. longiflorm × L hasonii and Asiatic lily × L. hansonii have been successful [14]. In some cases, stigma pollination by mixed incongruous pollen is used to overcome the pre-fertilization barrier in lily breeding, and it performs better than cut-style pollination by single male pollen [22].…”

Occurrence of 2n gametes in the F1 hybrids of Oriental × Asiatic lilies (Lilium): Relevance to intergenomic recombination and backcrossing

“…The two groups of cultivars, viz., Oriental and Asiatic hybrids, were all diploids (2n = 2x = 24) and were hybridized through cut-style pollination and cultured by either: embryo, embryo-sac or ovule culture methods (Van Tuyl et al, 1991;Van Creij et al, 2000). In all, 10 Oriental and six Asiatic hybrids were used for the production of F 1 OA hybrids, among which the 2n gamete producing genotypes were selected (Table 1) ( Barba-Gonzalez et al, 2004).…”

Inter-Simple Sequence Repeat Data Reveals High Genetic Diversity in Wild Populations of the Narrowly Distributed Endemic Lilium regale in the Minjiang River Valley of China

“…Since the introduction of L . regale to North America during the period from 1907 to 1911 by Wilson [ 8 ],due to its vigorous growth and resistance to diseases[ 9 , 10 , 11 ], it has been widely used as a parent in breeding programs and this has led to the production of many hybrid cultivars [ 12 ],including some resistant to the devastating wilt disease of lilies [ 8 ].…”