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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #312980

Research Project: Genetic Enhancement of Lettuce, Spinach, Melon, and Related Species

Location: Crop Improvement and Protection Research

Title: Host range of Verticillium isaacii and Verticillium klebahnii from artichoke, spinach, and lettuce

Author
item GURUNG, SURAJ - University Of California
item SHORT, DYLAN - University Of California
item HU, XIAOPING - University Of California
item SANDOYA, GERMAN - University Of California
item Hayes, Ryan
item KOIKE, STEVE - University Of California - Cooperative Extension Service
item SUBBARAO, KRISHNA - University Of California

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2015
Publication Date: 2/4/2015
Citation: Gurung, S., Short, D.P., Hu, X., Sandoya, G., Hayes, R.J., Koike, S., Subbarao, K.V. 2015. Host range of Verticillium isaacii and Verticillium klebahnii from artichoke, spinach, and lettuce. Plant Disease. doi: 10.1094/PDIS-12-14-1307-RE.

Interpretive Summary: Verticillium is a related group of soil-living fungal species. Many can cause wilting diseases of crop plants. Five new species were recently described. Among these are V. isaacii and V. klebahnii, both of which occur in agricultural soils in coastal California and have been recovered from healthy and diseased spinach and lettuce plants. Since they are a newly described species and have been isolated from commercial crops, their ability to cause disease on a broader range of crops important to the economy of coastal California needs to be investigated. Multiple strains of V. isaacii and V. klebahnii were tested for their ability to cause disease on eight crops (artichoke, cauliflower, eggplant, lettuce, pepper, tomato, spinach and strawberry). The species V. dahliae, which commonly causes the disease Verticillium wilt in coastal California, was included. Additionally, 13 lettuce accessions or cultivars previously known to possess resistance to V. dahliae were tested to determine if they are also resistant against V. isaacii and V. klebahnii. All but one V. isaacii strain and all V. klebahnii strains were unable to cause disease on most of the crops tested. One V. isaacii strain caused wilt on artichoke and the lettuce cultivar Salinas. Most V. isaacii and V. klebahnii strains caused varying degrees of Verticillium wilt on strawberry. Lettuce lines resistant to V. dahliae also exhibited resistance to V. isaacii and V. klebahnii. Thus, occasional isolates of V. isaacii and V. klebahnii could potentially become pathogens of coastal California crops but resistance developed against V. dahliae in lettuce offers resistance to both species.

Technical Abstract: Verticillium is a genus that includes major vascular wilt pathogens. The recent multilocus phylogenetic analyses of the genus identified 5 new species including V. isaacii and V. klebahnii, both of which occur in agricultural soils in coastal California, and have been isolated from asymptomatic and diseased spinach and lettuce plants. Since they are a newly described species and have been isolated from commercial crops, their pathogenicity and virulence on a broader range of crops important to the region need to be investigated. Isolates of V. isaacii and V. klebahnii along with the type isolates of V. dahliae for races 1 and 2 were inoculated on eight crops (artichoke, cauliflower, eggplant, lettuce, pepper, tomato, spinach and strawberry) in a greenhouse, incubated for 8 wk, and assessed for disease severity to determine their relative host ranges. Additionally, 13 lettuce lines resistant to race 1 and partially resistant to race 2 of V. dahliae were screened against V. isaacii and V. klebahnii to evaluate their responses to these species. Three out of four V. isaacii and four out of four V. klebahnii isolates tested were non-pathogenic on all crops tested except those indicated below. One V. isaacii isolate caused wilt on artichoke and the lettuce cultivar Salinas and most isolates of both species caused varying degrees of Verticillium wilt on strawberry. Lettuce lines resistant to V. dahliae race 1 and partially resistant to V. dahliae race 2 also exhibited resistance to two isolates each of V. isaacii and V. klebahnii tested. Thus, occasional isolates of V. isaacii and V. klebahnii could potentially become pathogens of coastal California crops but resistance developed against V. dahliae also offers resistance to the pathogenic isolates of both species at least in lettuce.