Barriers preventing hybridisation ofLathyrus odoratuswithL. chloranthusandL. chrysanthus

Abstract

Although growth of pollen tubes to the bases of the styles and to ovules was observed when shorterstyled cultivars were used, hybridisation barriers acting around the time of fertilisation prevented the production of embryos. In L chloranthus × L odoratus crosses, cultivar had no effect on post-fertilisation barriers causing embryo failure. Endosperm degeneration was presumed to be the cause of embryo failure.Keywords Lathyrus; interspecific hybridisation; breeding barriers; embryo development; embryo rescue Abstract Interspecific hybridisation of the sweet pea, Lathyrus odoratus L., with two yellow flowered relatives, Lathyrus chloranthus Boiss. and L. chrysanthus Boiss., was undertaken with the aim of transferring yellow flower colour into the sweet pea. Initial reciprocal cross pollinations of L odoratus 'Original', with the two species, produced no viable seed, suggesting the presence of interspecific hybridisation barriers. Observation of events following further reciprocal cross pollinations confirmed the presence of hybridisation barriers which prevented the formation of hybrid embryos in all cross combinations except L. chloranthus × L. odoratus. Post-fertilisation hybridisation barriers subsequently prevented the maturation of such hybrid embryos. Further crosses using a range of sweet pea cultivars indicated varying degrees of impediment to hybridisation depending on the cultivar used. Prefertilisation hybridisation barriers which prevented the growth of foreign pollen tubes to the bases of styles were observed in L. odoratus × L. chloranthus crosses and reciprocal L odoratus × L chrysanthus crosses involving long-styled L. odoratus cultivars. H92077

Pollen-Tube Competition, Siring Success, and Consistent Asymmetric Hybridization in Louisiana Irises

“…Asymmetric hybridization appears to be common in both plants (Buchholz et al 1935;Lewis and Crowe 1958;de Nettancourt 1977de Nettancourt , 1984Kiang and Hamrick 1978;Levin 1978;Williams and Rouse 1988;Gore et al 1990) and animals (Coyne and Orr 1989;Kaneshiro 1990;Howard and Gregory 1993;Palumbi 1994;Wade et al 1994). However, the pattern found in Louisiana irises is qualitatively different from that reported in other plant species, where short-styled taxa usually are less successful at fertilizing long-styled relatives than vice versa (Buchholz et al 1935;Smith 1970;Kiang and Hamrick 1978;Levin 1978;Gore et al 1990;Herrick et al 1993). Iris fulva has shorter styles than both I. brevicaulis and I. hexagona, yet is more successful than either in siring seeds on heterospecific mothers.…”

“…Thus, pollen-tube attrition may provide a late-acting advantage to con specific pollen. In some plant species, differences in fertilization ability after pollen-tubes have reached the ovary also can cause hybrid zygotes to be produced at low frequency (Sprague 1982;Williams et al 1986;Williams and Rouse 1988;Herrick et al 1993). At present we have no evidence that such a mechanism occurs in Louisiana irises.…”

Efficacy of Biotechnological Approaches to Raise Wide Sexual Hybrids

“…This reduces the distance through which pollen tubes have to grow to reach the ovules. Application of suitable medium on the stump before pollination may facilitate pollen germination Interspecifi c crosses of corn (Heslop-Harrison et al 1985 ), Lilium (van Tuyl et al 1991 ;Janson et al 1993 ), Lathyrus (Herrick et al 1993 ), Fritillaria (Wietsma et al 1994 ) (continued) hybrids were realized in some cereals and legumes (Van Tuyl and De Jeu 2003 ;Shivanna 2003 ). However, so far, there are no evidences to indicate the involvement of immunochemical reactions in crossability barriers, and there have been no additional reports on the success of immunosuppressors in realizing wide hybrids.…”

Interspecific hybridization in perennial species of Lathyrus (fabaceae)

“…Unlike many Lathyrus species, it has been reported to form natural hybrids with the related species L. sylvestris in northern France [2]. This is unusual as, despite the uniformity of chromosome number in the genus (2n = 2x = 14), interspecific hybrids are in general difficult to produce using conventional plant breeding methods [8,21]. This can be seen from the fact that after decades of attempts at interspecific hybridization in a genus with over 150 species, only 19 interspecific hybrids have been reported [6].…”

“…This can be seen from the fact that after decades of attempts at interspecific hybridization in a genus with over 150 species, only 19 interspecific hybrids have been reported [6]. Also, there are several reports of unsuccessful interspecific hybridizations within this genus [8,13,21].…”