Genome Mapping and Molecular Breeding in Lathyrus

Abstract

The genus Lathyrus L. is a member of the Vicieae tribe (family Fabaceae), the other members of which are Pisum, Lens and Vicia. Lathyrus consists of ca. 160 species (Allkin et al. 1986). The most comprehensive infrageneric classification of Lathyrus by Kupicha (1983) separated the species into 13 sections based on morphological traits (Orobus, Lathyrostylis, Lathyrus, Orobon, Pratensis, Aphaca, Clymenum, Orobastrum, Viciopsis, Linearicarpus, Nissolia, Neurolobus and Notolathyrus). Recent molecular-based studies have supported the classification system of Kupicha (1983) for some species (Croft et al. 1999); however, studies of the chloroplast DNA of 42 Lathyrus species (Asmussen and Liston 1998) and AFLP analysis of 18 species (Badr et al. 2002) suggest that reclassification of some species to different sections may be required. The most economically important and widely cultivated Lathyrus species is L. sativus. L. sativus is grown as a forage crop and is also cultivated for human consumption and as a stock feed. Other important Lathyrus species are L. cicera (dwarf chickling), L. tingitanus, L. ochrus, L. hirsutus, and L. sylvestris as grain and/or forage crops and L. odoratus (sweet pea) and L. latifolius, which are ornamentals. The main center of diversity of Lathyrus species is the eastern Mediterranean, with smaller centers of diversity in North and South America (Kupicha 1983). L. sativus is thought to have originated in southwest and central Asia; however, its natural distribution has been obscured by widespread cultivation, even in its presumed center of origin (Smartt 1984). Domestication of L. sativus is evidenced by remains of L. sativus seed from the Balkans, dated at 8000 BC (Kislev 1989), and from Jarmo (Iraq), dated at 6000 BC (Helbaek 1965). L. sativus is now widely distributed throughout the world. However, despite the widespread distribution of L. sativus and the length of time that it has been cultivated, it has not progressed as a pulse crop to the same extent as other Mediterranean pulses (field pea, lentil and chickpea). Smartt (1984) hypothesized that the lack of progress of L. sativus as a pulse crop might have been due to its other and perhaps more important use as a forage crop; thus the countervailing selection pressures for both purposes may have cancelled each other out.