Seed protein diversity and its implications on the relationships in the genus Lathyrus L. (Fabaceae)

Abstract

Seed protein diversity as revealed by variation in SDS-PAGE has been used to re-assess the taxonomic relationships between 34 species representing nine sections and the two subgenera of the genus Lathyrus L. A total number of 44 protein bands, with molecular weight (MW) ranging between 99.5 and 14.4 KD were recorded in the electropherograms of the species studied. These bands were used as binary characters and analyzed by the NTSYS-pc. program package using the UPGMA clustering method. The relationships of the studied taxa as revealed by the produced phenogram are discussed in relation to previous infrageneric classifications of Lathyrus. The results support the following conclusions: 1. The delimitation of Lathyrus species in the two subgenera Lathyrus and Orobus may be supported. The grouping of the three sections Pratensis, Lathyrostylis and Orobus in subgenus Orobus is recommended; the circumscription of these sections is validated. Other sections may be delimited in subgenus Lathyrus. 2. The circumscription of section Lathyrus is somewhat different compared to previous treatments. Nine of 15 species of this section are grouped together. Two species from section Linearicarpus i.e. L. angulatus & L. inconspicuus and one species of section Orobus i.e. L. davidii are close to these species, but the inclusion of L. tuberosus in section Lathyrus is questionable. 3. The separation of L. gorgoni and L. rotundifolius in section Gorgonia Dogan is not supported, these two species are included in section Lathyrus. 4. Five species i.e. L. blepharicarpus, L. cicera, L. marmoratus, L. pseudocicera and L. sativus of section Lathyrus may be transferred to section Clymenum. The latter section should be viewed in a broader sense and may be enlarged to include the monotypic section Neurolobus. 5. Section Linearicarpus appears to be unnatural group; the species of this section except L. pinnonicus and L. sphaericus are grouped in section Lathyrus. 6. The grouping of these two species with L. nissolia in the monotypic section Nissolia is proposed. 7. The distinction of section Aphaca is supported