Plant Disease (2011) 95, 1224-1232

Zahi K. Atallah, Karunakaran Maruthachalam, Gary E. Vallad, R. Michael Davis, Steven J. Klosterman and Krishna V. Subbarao (2011)
Analysis of Verticillium dahliae suggests a lack of correlation between genotypic diversity and virulence phenotypes
Plant Disease 95 (10), 1224-1232
Abstract: Verticillium dahliae causes severe wilt and recurring losses in numerous agricultural and ornamental hosts worldwide. Two virulence phenotypes (races) have been identified based on the Ve resistance gene and its homologs but their distribution and evolutionary history are unknown. Sequence analyses of the intergenic spacer of the ribosomal DNA and amplified fragment length polymorphism markers suggested an absence of correlation between genotypic diversity and virulence phenotypes. Additionally, both race 1 and 2 phenotypes were isolated in various geographic regions and hosts. Sustained levels of migration of both virulence phenotypes among various geographic regions were evident, and the study also suggested that both virulence phenotypes infect a variety of hosts, regardless of the availability of resistant cultivars. Given the high genotypic diversity observed in V. dahliae, more than the two known virulence phenotypes may be present in nature but not yet identified because of the current lack of sources of resistance other than the Ve gene and its homologs. The inclusion of various genotypes exhibiting the same virulence phenotype may greatly improve the long-term effectiveness of resistance to race 2 of V. dahliae regardless of the host. This study also confirms the transcontinental gene flow and high genotypic diversity of V. dahliae affecting lettuce in coastal California regardless of the molecular markers employed.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Krishna V. Subbarao, Steven J. Klosterman, Gary E. Vallad

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Verticillium dahliae	Lettuce (Lactuca)	U.S.A. (SW)