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Additional Sources of Stem Canker Resistance in Soybean Plant Introductions
Author(s) -
Tyler Jeff M.
Publication year - 1995
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1995.0011183x003500020015x
Subject(s) - biology , backcrossing , canker , germplasm , allele , genotype , plant disease resistance , resistance (ecology) , genetics , botany , horticulture , gene , agronomy
Stem canker caused by Diaporthe phaseolorum (Cooke & Ellis) Sacc. f. sp. meridionalis Morgan‐Jones can cause significant yield losses in soybean [ Glycine max (L.) Merr.] in the southern USA. Many genotypes are known to be resistant to the disease; however, little is known about the inheritance of resistance and allelic relationships of genes conferring resistance. The objective of this study was to determine the inheritance of resistance in two germplasm accessions, PI 230976 and PI 398469, and define allelic relationships with the four described genes. Each PI was crossed with a susceptible genotype, J77‐339, and the four fines carrying Rdcl , Rdc2 , Rdc3 , or Rdc4 . Crosses were made in the field at Stoneville, MS, in 1992, and F 1 backcrosses to J77‐339 were made in 1993. Plants of parents and 10 F 2 populations were toothpick inoculated in the field in 1993. The F 2:3 and backcross populations were later evaluated in a greenhouse. The F 2 populations derived from J77‐339 × PI 230976 and J77‐339 × PI 398469 approached a 3 resistant/1 susceptible ratio indicating that a single dominant gene for resistance is carried by each plant introduction. The F 3 data confirmed this result. Backcross data substantiated complete dominance. Response of all F 2 populations derived from crosses with genotypes carrying known genes suggested a 15:1 ratio indicating nonallelism. It is not known if both plant introductions carry the same gene. These sources of resistance may lessen genetic vulnerability should new virulent isolates overcome sources now used by breeders