Inheritance of Resistance to Fusarium Wilt in Two Common Bean Races

Abstract

Fusarium wilt in common bean (Phaseolus vulgaris L.) caused by Fusarium oxysporum Schlechtend. Fr. forma specialis phaseoli Kendrick and Snyder (Fop) occurs worldwide and can result in severe yield loss. Because cultural methods to control disease loss are not completely effective, cultivars with genetic resistance are needed. The objectives of this study were to determine whether genetic control of resistance to Fop race 4 differs between germplasm of races Durango and Mesoamerica of common bean and to estimate heritability of resistance found in race Mesoamerica. Resistant and susceptible lines of races Durango and Mesoamerica were crossed within races to produce F2 and F3 progeny. Reaction to Fop was evaluated using a root‐dip inoculation method and scored using a CIAT disease severity scale from one to nine. F2 populations derived from race Durango parents showed a 3:1 (resistant/susceptible) plant segregation ratio, and F3 progeny tests confirmed that resistance was controlled by a single dominant gene. F2 data from crosses between parents of race Mesoamerica had continuous distributions for reaction to Fop race 4, suggesting polygenic control of resistance. The narrow‐sense heritability estimate derived from midparent–offspring regression of 10 F2 populations derived from Mesoamerican parents was 0.85 ± 0.34, and realized heritability estimates ranged from 0.25 ± 0.19 to 0.60 ± 0.16 among five populations. The heritability estimates as well as the continuous variation in disease severity observed support the hypothesis that resistance to Fop race 4 among parents of race Mesoamerican is polygenic.

Inheritance of resistance to Fusarium oxysporum f. sp. phaseoli Brazilian race 2 in common bean

“…Similar results were also reported by Cross et al (2000), with race 4 of the fungus, in crosses involving lines originated from the Durango race. However, in lines of Mesoamerican origin similar to those used here, the authors evidenced the existence of polygene control of resistance.…”

“…Higher heritability estimates for resistance to Fusarium wilt than observed here were obtained by Cross et al (2000) ( = 0.85). However, this estimate was obtained using the regression of the parent means and the mean of the F 2 generation, involving the segregating populations (F 2 ), i.e., the estimate obtained by Cross et al (2000) aims at the selection of populations rather than at F 2 plants. In this case, the estimate is not directly comparable to the one obtained here.…”

“…There are some reports of ge- netic control of resistance; the first was probably the study of Ribeiro & Hagedorn (1979), who identified the presence of only one gene with a dominant allele conferring resistance. More recently, other results were reported for the genetic control of resistance (Salgado et al, 1995;Cross et al, 2000;Brick et al, 2004). No report was found on the genetic control of resistance to this pathogen using exclusively germplasm developed in Brazil, nor any information about the use of the estimated mean and variance components to study this trait.…”

Resistance to Fusarium wilt in common bean

“…Pereira et al (2009) evaluated six crosses involving three resistant and four susceptible lines, and observed complete dominance in Fop resistance genetic control in common bean. The same result was reported by Cross et al (2000) for two F 2 generations of crosses between Fop-resistant and Fop-susceptible Durango common bean parents.…”

“…The integrated disease management of Fusarium Wilt (FW) is limited to crop rotation, seed treatment and use of resistant cultivars. Cross et al (2000) and Pereira et al (2009) stated that the use of resistant cultivars is the most effective method of controlling the economic losses caused by Fusarium wilt.…”