Genetics of virulence in Ascochyta rabiei

Peever, T.L. and Chen, W. and Abdo, Z. and Kaiser, W.J. (2012) Genetics of virulence in Ascochyta rabiei. Plant Pathology. pp. 1-7.

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In order to critically test the hypothesis that virulence variation in the Ascochyta rabiei ⁄ chickpea pathosystem is a discrete character under simple genetic control, a genetic cross was made between a highly virulent isolate of A. rabiei from Syria and a less virulent isolate from the USA. Two independent virulence assays conducted by inoculating susceptible and resistant chickpea cultivars under controlled conditions with 77 independent progeny isolates from this cross revealed a continuous distribution of disease phenotypes. Bimodality, as would be predicted for the segregation of virulence under simple genetic control, was not supported by statistical tests of the progeny phenotype distribution. ANOVA revealed highly significant pathogen-genotype · host-genotype interactions demonstrating the segregation of genes controlling specialization on the two cultivars tested. These interactions could be localized to two isolates that changed virulence rank on the cultivars. It was concluded that variation in virulence to these two cultivars is under quantitative genetic control. If this conclusion applies to other cultivars, it can be speculated that the discrete categories of virulence variation identified in previous studies were probably the result of incomplete sampling of host resistance or pathogen virulence variation and ⁄ or of selection for increased virulence in contemporary A. rabiei populations.

Item Type: Article
Uncontrolled Keywords: aggressive race, chickpea, Cicer arietinum, necrotrophic
Author Affiliation: Washington State University, PO Box 646430, Pullman, WA 99164-6430
Subjects: Crop Improvement > Genetics/Genomics
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 14 Mar 2014 09:31
Last Modified: 14 Mar 2014 09:31
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