Inheritance of resistance to common bacterial blight in four tepary bean lines

High levels of resistance to common bacterial blight caused by Xanthomonas campestris pv, phaseoli (Smith) Dye (Xcp) have been observed for tepary bea n (Phaseolus acutifolius A. Gray var. latifolius Freeman), However, the inh eritance of resistance from this source is unknown for many lines. The inhe ritance of common bacterial blight resistance was studied in four tepary be an lines crossed with the susceptible tepary bean MEX-114. Progenies were i noculated with a single Xcp strain 484a. Segregation ratios in the F-2 gene ration suggested that resistance in Neb-T-6-s and PI 321637-s was governed by one dominant gene, and Neb T-8a-s had two dominant genes with complement ary effects. These hypotheses for inheritance of resistance were supported by various combinations of F-10, F-3, BC1Pn Segregation data in all lines e xcept PI 321637-s where an additional minor-effect gene with recessive inhe ritance was indicated. Generation means analyses corroborated that multiple resistance genes were present in PI 321638-s. Lack of segregation for susc eptibility among testcrosses for allelism between Neb-T-6-s/PI 321637-s, Ne b-T-6-s/Neb-T-8a-s, PI 321637-s/Neb-T-8a-s, and PI 321637-s/PI 321638-s, su ggested that one or more loci conditioning resistance to common bacterial b light mere in common across the four tepary lines.