Genetics and mapping of adult plant rust resistance in soybean PI 587886 and PI 587880A

• Published in: Theoretical and applied genetics 2009-07, Vol.119 (2), p.271-280
• Main Authors: Ray, Jeffery D, Morel, Wilfrido, Smith, James R, Frederick, Reid D, Miles, Monte R
• Format: Article
• Language: English
• Subjects: Agriculture; Basidiomycota - isolation & purification; Basidiomycota - physiology; Biochemistry; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Classical genetics, quantitative genetics, hybrids; Fundamental and applied biological sciences. Psychology; Genes; Genetic Linkage; Genetics; Genetics of eukaryotes. Biological and molecular evolution; Glycine max - genetics; Glycine max - immunology; Immunity, Innate - genetics; Life Sciences; Methods, theories and miscellaneous; Minisatellite Repeats - genetics; Original Paper; Phenotype; Physical Chromosome Mapping; Plant Biochemistry; Plant Breeding/Biotechnology; Plant Diseases - genetics; Plant Diseases - immunology; Plant Diseases - microbiology; Plant Genetics and Genomics; Pteridophyta, spermatophyta; Seeds; Soybeans; Vegetals
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-009-1036-z

Two soybean accessions, PI 587886 and PI 587880A, previously identified as having resistance to Phakospora pachyrhizi Syd. (soybean rust, SBR) were used to create two populations (POP-1 and POP-2) segregating for SBR resistance. F₂-derived F₃ (F₂:₃) families from each population were grown in a naturally SBR-infected field in Paraguay to determine inheritance and map resistance genes. Over 6,000 plants from 178 families in POP-1 and over 5,000 plants from 160 families in POP-2 were evaluated at R5 for lesion type: immune reaction (IR), reddish-brown (RB), or tan (TAN) colored lesions. Based on the lesion type present, each F₂:₃ family was rated as resistant, segregating or susceptible and this classification was used to infer the F₂-phenotype and genotype. For both populations, the F₂ segregation ratios fit a 1:2:1 (resistant:segregating:susceptible) ratio expected for a single gene (P > 0.05). The RB lesions occurred almost exclusively in the heterozygous class, indicating incomplete dominance under the conditions of this study. Molecular markers flanking the locations of the known resistance genes were used to map the resistance gene in both populations to the Rpp1 locus. However, evaluation of PI 587886 and PI 587880A against eight P. pachyrhizi isolates indicated that the resistance allele in these two accessions was different from Rpp1. This test also demonstrated that these accessions were resistant to at least one P. pachyrhizi isolate collected in the southern US. This is the first report of using an adult plant field-screen with natural rust pressure to map SBR resistance.