Interspecific Hybridization in the Genus Lens Applying in Vitro Embryo Rescue

Abstract

Four different hybridization experiments were carried out to obtain interspecific hybrids with Spanish cultivars of lentil (Lens culinaris M.). In hybridization experiments I and II, undertaken with only pollination and pollination with the addition of gibberellic acid after fertilization, respectively, no lentil hybrids were recovered. A single interspecific hybrid with L. odemensis was obtained in experiment III using the embryo rescue protocol of Cohen et al. (1984), in this case, a crossing efficiency of 0.11% and a rescue efficiency of 2.5% were obtained. Hybridization experiment IV used a specific embryo rescue protocol developed in this study. In this experiment, ovule-embryos of 18 DAP were cultured on MS salts with 1% sucrose and 1 μM IAA + 0.8 μM KN; after two weeks, embryos were released from the ovular integuments and cultured on the same medium for another two weeks in upright position. Afterwards, the embryos were transferred to test tubes containing the same medium and one month later plantlets were obtained. Using the above protocol, out of a total of 1707 pollinations, 6 interspecific hybrids with L. odemensis, 2 with L. nigricans and one with L. ervoides were recovered, yielding on average a crossing efficiency of 0.53% and an average rescue efficiency of 8.26%. Taking into consideration only the interspecific crossing blocks in which hybrids were recovered, the crossing efficiency with L. odemensis was 9%, while with both L. nigircans and L. ervoides the crossing efficiencies were 3%. Rescue efficiencies based on hybrids recovered per number of ovules cultured ranged between 50-100%.

Legume Crops Phylogeny and Genetic Diversity for Science and Breeding

“…Pod abortion took place when the cultivated lentil was crossed with either L. ervoides or L. nigricans (Abbo and Ladizinsky, 1991). In vitro methods of embryo-ovule rescue are used overcome the post-fertilization interspecific barrier (Fratini and Ruiz, 2006;.…”

Lentil

“…A comparison between the geographical patterns of the wild species and the cultivated forms (see Cubero et al 2009 ) seems to verify the introgression hypothesis as orientalis is the only wild form spreading eastward, ervoides to the Ethiopian region, and both nigricans and ervoides to the west. Nonetheless, the latter two species do not readily cross with culinaris as hybrids result in embryo abortion Fratini and Ruiz 2006 ), but sporadic crosses through a long period of time cannot be readily dismissed. Besides, in the same way as odemensis was separated from nigricans because of the differential fertility level with cultigens, other strains of nigricans and ervoides could have behaved in a similar way.…”

“…However, later on crosses with other accessions of nigricans were observed to be unviable . , which could possibly explain why certain accessions of odemensis are freely crossed with culinaris (Ladizinsky 1979 ) while others need embryo rescue (Fratini and Ruiz 2006 ). Lens odemensis is cross incompatible with nigricans and ervoides due to hybrid embryo abortion .…”

“…Lens nigricans × L. ervoides interspecifi c hybrids are vegetatively normal but completely sterile . Fratini and Ruiz ( 2006 ) carried out extensive crosses between L. c . ssp.…”

Functional Genomics For Crop Improvement

“…Embryo rescue is still being used in breeding programs for the generation of genetic variability and incorporation of desirable traits from inter-specific or inter-generic hybrids (for review see Sharma et al 1996). Embryo rescue to develop improved germplasm has been successfully used in legumes (Clarke et al 2006;Fratini and Ruiz 2006;Fratini and Ruiz 2008), cereals (Rodrangboon et al 2002;Tikhenko et al 2008), oilseed crops (Luhs and Friedt 1994;Muangprom et al 2006), horticultural crops Drew et al 2006;Yang et al 2007;Tian and Wang 2008) and many other economically important plant species. A more sophisticated approach to the creation of genetic variability was through somatic cell hybridization by fusion of protoplasts, and in the late 1970s several significant breakthroughs occurred in addition to publication of a number of reports pertaining to basic protoplast isolation and culture (for reviews see Lynch et al 1993;Waara and Glimelius 1995;Davey et al 2005;Liu et al 2005).…”