Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/9/2007
Publication Date: 6/1/2007
Citation: Wang, M.L., Morris, J.B., Barkley, N.L., Dean, R., Jenkins, T., Pederson, G.A. 2007. Evaluation of Genetic Diversity of the USDA Lablab Purpureus Germplasm Collection Using Simple Sequence Repeat Markers. Journal of Horticultural Science and Biotechnology. 82:571-578. Interpretive Summary: Lablab or hyacinth bean (L. purpureus) can be used for green vegetable, seed production, forage, and green manure, as well as covering crops. The lablab leaves and seeds contain 20-28% protein with well balanced amino acids and the plants can produce big green biomass and stay green during drought. These features make lablab an ideal and nutritious forage crop. The USDA lablab germplasm collection contained 57 accessions and their genetic diversity was never evaluated. In the present report, the genetic diversity of lablab was assessed by DNA markers. The accessions can be classified into two forms: wild form and cultivated form. The wild form produced small biomass and seeds, whereas cultivated form produced large biomass and seeds. In our collection, there were only very few accessions which belong to the wild form. Furthermore, the accessions within the cultivated form contained moderate genetic diversity. Therefore, our lablab collection needs to be further expanded on both accession number and genetic diversity spectrum, especially for the wild form.
Technical Abstract: The genetic diversity of the USDA Lablab purpureus germplasm collection is unknown and was assessed by using polymorphic simple sequence repeat (SSR) markers derived from Medicago, soybean and cowpea. Phylogenetic analysis paritioned 47 representative accessions into two main clades (wild clade producing small seeds and cultivated clade, producing large seeds). Accessions in the wild clade could be distinguished from each other, whereas accessions in the cultivated clade cannot be easily resolved into clear groups. The wild clade is clearly diverged from the cultivated clade. The USDA cultivated subsp. purpureus collection contained moderate (limited) genetic diversity and needs to be expended. Some lablab amplicons were sequenced. The sequence similarity to Medicago truncatula was variable from amplicon to amplicon; however, sequence analysis of lablab amplicons from the same SSR showed that the sequence content of these amplicons was almost identical except for some single nucleotide polymorphisms (SNPs). Therefore, amplicons with different sizes from transferred SSRs can be used as DNA markers to distinguish germplasm accessions at the DNA fragment level. Futhermore, our genetic classification result was confirmed by morphological examination and sequence analysis.