Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2002
Publication Date: N/A
Interpretive Summary: Alfalfa is fourth in total acreage among U.S. crops and is a very important hay crop worldwide. Unfortunately, there are problems with alfalfa that cannot be solved without an influx of new genes. The related Asian species Medicago edgeworthii and Medicago ruthenica are a potential source of new genes, but they are difficult to cross with alfalfa. One possibility is to use molecular genetic techniques to identify new genes in the Asian species and to transfer them to alfalfa using gene transfer technology. Potential disease resistance genes can be identified by their DNA sequences. This report discusses evidence that several of these genes have been identified in the Asian species and may be a new source of disease resistance if transferred to alfalfa. The information in this report will be of value to both public and private alfalfa scientists.
Technical Abstract: Medicago edgeworthii and M. ruthenica are perennials from Asia, which have a remarkable ability to survive stress, but are genetically distant from cultivated alfalfa. In lieu of hybridization, potentially important genes from the Asian species could be transferred to alfalfa using transgenic techniques. Many plant disease resistance genes (R-genes) belong to the NBS-LRR superfamily and conserved domains in the NBS region of alfalfa and the two Asian species were studied using degenerate PCR primers. Several unique sequences were identified in the Asian species. Non-Toll/interleukin-type (non-TIR) sequences were markedly different from the TIR sequences. Screening for unique R-gene analogs in genetically distant Medicago species may be a very effective way of isolating potential new R-genes for transfer to alfalfa.