|BRACE, RYAN - Iowa State University|
|FEHR, WALTER - Iowa State University|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2012
Publication Date: 9/1/2012
Citation: Brace, R.C., Fehr, W.R., Graham, M.A. 2012. Inheritance and molecular mapping of an allele providing resistance to Cowpea mild mottle virus-like symptoms in soybean. Crop Science. 52(5):2109-2114.
Interpretive Summary: Cowpea mild mottle virus-like (CPMMV-L) causes damage to soybeans grown in Argentina, Brazil, Mexico, and Puerto Rico. In some areas of these countries, damage is so severe that soybeans are no longer grown commercially. Although the virus is not currently of economic importance for soybean production in the continental United States, it is a problem for private and public institutions that conduct soybean breeding research in nurseries located outside the continental United States. We have identified soybean lines that differ in their reaction to CPMMV-L. Using these lines, we have determined that resistance to CPMMV-L is due to a single recessive gene (Rbc1). Further, this gene has been mapped to a 3 cM region on soybean chromosome 18, near marker BARCSOYSSR_18_0443. This marker, and additional flanking markers, can be used by breeders to select resistance plants for use in soybean nurseries outside of the continental United States.
Technical Abstract: Damage to soybean [Glycine max (L.) Merr.] from Cowpea mild mottle virus-like (CPMMV-L) symptoms (family: Betaflexiviridae, genus: Carlavirus) has been of increasing concern in Argentina, Brazil, Mexico, and Puerto Rico. Soybean cultivars and lines differing in their reaction to the virus have been identified. The first objective of our study was to determine the genetic basis of resistance and susceptibility of F1 plants and 100 F2-derived lines from the cross of 'IA3023' (resistant) × 'IA3024' (susceptible) using natural field infection in Puerto Rico and Mexico during 2011. All of the F1 plants were susceptible and the segregation of F2-derived lines satisfactorily fit a ratio of 3 susceptible:1 resistant, which indicated that resistance was controlled by a recessive allele at a single locus. The second objective of our study was to determine the genetic location of the locus by genotyping 93 of the F2-derived lines. The molecular analysis identified a locus on chromosome 18 (Linkage group G) at the same estimated genetic position of the marker BARCSOYSSR_18_0443 (89.8 cM). The locus was flanked by BARCSOYSSR_18_0456 (88.6 cM) and BARCSOYSSR_18_0458 (91.0 cM). The locus was designated Rbc1 and the resistance allele in IA3023 was identified as rbc1. Markers tightly linked to the Rbc1 locus can be used to select resistant progeny in segregating populations from crosses between resistant and susceptible parents.