Abstract
Stem canker caused by the fungus Diaporthe phaseolorum f. sp. meridionalis is a disease that limits soybean cultivation. Phenotypic evaluations aiming at disease resistance require labor-intensive processes, as for instance handling and transport of phytopathogens. The use of DNA markers in the selective procedures eases certain phases, besides being practical, safe and reliable. A RAPD fragment of 588pb was identified among bulks of resistant and susceptible plants in the cross BR92-15454 (R) x IAC-11 (S). Through co-segregation, the distance between the resistance locus and the fragment was estimated at 7.4 ± 2.1 cM, with a Lodmax. of 23.072 (first year) and at 6.0 ± 3.4 cM with a Lodmax. of 7.806 (second year). The fragment was converted into a SCAR marker and digested with enzyme Hinc II, which made the classification in homozygous resistant, heterozygous resistant and susceptible plants possible. This SCAR marker is suitable for use in the improvement program conducted in Jaboticabal.
Highlights
One of the most important soybean diseases is stem canker with a highly destructive potential, as the first occurrences in the State of Paraná demonstrated
Nowadays the disease caused by the fungus Diaphorte phaseolorum f. sp. meridionalis (Dpm) is disseminated across all producing regions in Brazil
First studies aiming at the determination of resistance inheritance were performed with the fungus Diaphorte phaseolorum var. caulivora (Dpc)
Summary
One of the most important soybean diseases is stem canker with a highly destructive potential, as the first occurrences in the State of Paraná demonstrated. Nowadays the disease caused by the fungus Diaphorte phaseolorum f. First studies aiming at the determination of resistance inheritance were performed with the fungus Diaphorte phaseolorum var. Kilen et al (1985) inoculated F2 plants (Tracy-M x J77-339) and identified two dominant genes of disease resistance in the cultivar Tracy-M. Wendel and Allen (1986) identified one dominant and another partially dominant gene in Tracy-M, Dpc and Dpc, respectively. Kilen and Hartwig (1987) verified that the lines X404 and X412 presented the genes Rdc and Rdc, respectively, identified earlier in cultivar Tracy-M by Kilen et al (1985). Bowers Jr et al (1993) confirmed that inheritance in Tracy-M is controlled by two resistance genes
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