Sources of rust resistant germplasm and inheritance of rust reaction and hybrid plant abnormalities in common bean

Bean rust, caused by the fungal pathogen Uromyces appendiculatus (Pers.) Unger var. appendiculatus is a major disease limiting common bean (Phaseolus vulgaris L.) yield and quality worldwide. Bean germplasm of wide origins was evaluated for reaction to a diverse collection of rust races/pathotypes. The presence or absence of hairs on the abaxial leaf surface of the bean germplasm was also recorded. Bean rust differential cultivars/lines, used for rust race identification, had specific resistance (SR) to many of the races/pathotypes tested. Bean germplasm from Malawi lacked broad SR but had adult plant resistance (APR). Many of the Malawian germplasm with APR were glabrous and no association was observed between APR and abaxial leaf pubescence (ALP). Inheritance of SR, APR, ALP, flower and stem color and their associations were determined in recombinant inbred lines (RILs) from six common bean crosses. Inheritance of SR to rust was primarily controlled by single major genes. Inheritance of APR also was governed by a single major gene. An epistatic interaction was detected between SR and APR such that APR to a specific race/pathotype cannot be measured in a plant with SR to the same race/pathotype. ALP was controlled by a single major gene. Flower color (FC) and Stem color (SC) were governed by two different major genes. No association or linkage was detected between SR or APR and ALP, FC or SC. Inheritance of three hybrid plant abnormalities (HPA), plant crippling (C), plant lethality (L), and leaf variegation (V) and SR to rust was studied in F$\sb2$ and F$\sb3$ progenies derived from some common bean crosses. A single dominant gene controlled SR in cross \u27PC-50\u27 x Chichara 83-109. Duplicate recessive genes controlled C in the same cross. Inheritance of C and L were each determined by the interaction of two different recessive genes. No association was detected between SR and the three HPA traits, FC, SC, L or V