Submitted to: Genome
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/14/2005
Publication Date: 6/30/2006
Citation: Wang, M.L., Mosjidis, J.A., Morris, J.B., Dean, R.E., Jenkins, T.M., Pederson, G.A. 2006. Genetic diversity of crotolaria germplasm assessed throgh phylogenetic analysis of est-ssr markers. Genome 49:707-715. Interpretive Summary: Species in the genus Crotolaria can be used as source of fibers, forage, silage, green manure, cover crops and ornamentals. Very few species have been biochemically assayed or genetically classified. Although C. juncea is a popular cultivated species (American Tropic Sun variety is an excellent example), the genetic diversiyy of its germplasm has not been assessed previously. Twenty-six accessions representing four species have been evaluated by simple sequence repeats (SSRs). The accessions were classified into four main groups, each of which is consisted primarily of the four species. Some misnamed accessions were identified and confirmed by both morphological data and genetic data. Some amplicons from Crotolaria were sequenced. Their sequences showed a high similarity (with 89% sequence identity) to Medicago truncatula. This is the first report of application of DNA markers on Crotolaria species.
Technical Abstract: The genus Crotolaria comprises a large number of species, many of which have economic value. An assessment of genetic diversity of the Crotolaria germplasm is lacking. Polymorphic expressed sequence tag - simple sequence repeat (EST-SSR) markers derived from Medicago and soybean were used to assess the genetic diversity of Crotolaria germplasm collection consisting of 26 accessions representing four species. A total of 130 bands were detected with a mean number of 4.64 alleles per marker. The accessions were classified into four main groups, each of which consisted primarily of four species. Morphological observation also confirmed the genetic classifiction of the accessions. However, there were a couple of exceptions for the classification: one accession each from C. juncea and C. Spectabilis, respectively were classified into the group mainly representing C. retusa. Morphological comparision confirmed that these two accessions were misnamed during curation or conservation and should belong to C. retusa. The phylogenetic analysis suggests that C. juncea is much closer to C. retusa and C. spectabilis than to C. pallida, and C. retusa is much closer to C. spectabilis than other species. Highly distinguishing markers are required to further classify accessions within C. juncea. Some amplicons from Crotolaria were sequenced and their sequences showed a high similarity (with 89% sequence identity) to Medicago truncatula from which the EST-SSR primers were designed, however, the simple sequence repeat (SSR) was completely deleted in Crotolaria. This is the first report of application of DNA markers on Crotolaria species.