ABSTRACT
A set of 219 DNA clones derived from mungbean (Vigna radiata), cowpea (V. unguiculata), common bean (Phaseolus vulgaris), and soybean (Glycine max) were used to generate comparative linkage maps among mungbean, common bean, and soybean. The maps allowed an assessment of linkage conservation and collinearity among the three genomes. Mungbean and common bean, both of the subtribe Phaseolinae, exhibited a high degree of linkage conservation and preservation of marker order. Most linkage groups of mungbean consisted of only one or two linkage blocks from common bean (and vice versa). The situation was significantly different with soybean, a member of the subtribe Glycininae. Mungbean and common bean linkage groups were generally mosaics of short soybean linkage blocks, each only a few centimorgans in length. These results suggest that it would be fruitful to join maps of mungbean and common bean, while knowledge of conserved genomic blocks would be useful in increasing marker density in specific genomic regions for all three genera. These comparative maps may also contribute to enhanced understanding of legume evolution.
ABSTRACT
The Phytophthora root and stem resistance locus Rps1 has been mapped to linkage group N of the USDA-ARS soybean molecular map, approximately 2 cM from locus A071-1. To determine if A071-1 polymorphisms exist that distinguish and tag different Rps1 alleles, germplasms containing the seven Rps1 alleles were screened with eight enzymes for pA071-detectable polymorphisms. Six enzymes revealed at least one polymorphic fragment. All six detected a polymorphism at A071-1 as determined by restriction fragment length polymorphism mapping, comparison to an EMBL3 clone containing locus A071-1, and Southern hybridization with probes specific for locus A071-1. Screening of the Rps1 donors and 24 Rps1-and 15 Rps1-containing U.S. soybean varieties showed that locus A071-1 exhibited three polymorphisms with each enzyme. The polymorphisms detected by one enyme did not always correlate with those detected by the other four, suggesting that multiple mutation events may be responsible for the different A071-1 polymorphisms. Although no combination of alleles distinguished Rps1-and Rps1-containing genotypes, polymorphism at A071-1 made it possible to distinguish five groups of soybean germplasms. Thus, the unusual polymorphism of locus A071-1 should useful for following Rps1 inheritance in many breeding programs.
Subject(s)
Education, Nursing/history , Language , Nursing Care , Female , History, 20th Century , Humans , Nurse-Patient Relations , United States , Women's Rights/historyABSTRACT
We have constructed a genetic map for soybean and identified associations between genetic markers and quantitative trait loci. One-hundred-fifty restriction fragment length polymorphisms (RFLPs) were used to identify genetic linkages in an F2 segregating population from an interspecific cross (Glycine max x Glycine soja). Twenty-six genetic linkage groups containing ca. 1200 recombination units are reported. Progeny-testing of F2-derived families allowed quantitative traits to be evaluated in replicated field trials. Genomic regions, which accounted for a portion of the genetic variation (R2 = 16 to 24%) in several reproductive and morphological traits, were linked to RFLP markers. Significant associations between RFLP markers and quantitative trait loci were detected for eight of nine traits evaluated. The ability to identify genes within a continuously varying trait has important consequences for plant breeding and for understanding evolutionary processes.
