10th INTERNATIONAL VERTICILLIUM SYMPOSIUM 16-20 ...

ON VERTICILLIUM DAHLIAE PLASTICITY ANDFLEXIBILITY: A CASE STUDY OF CROSS-PATHOGENICITYBETWEEN POTATOES AND SUNFLOWERSHASSNA A. ALKHER 1 , ABDELBASSET EL HADRAMI 1* , KHALID Y.RASHID 2 , LORNE R. ADAM 1 , AND FOUAD DAAYF 1*1 Department of Plant Science, 222 Agriculture Building, University of Manitoba, Winnipeg, Manitoba,R3T 2N2, Canada;2 Agriculture and Agri-Food Canada, Morden Research Station, Unit 100 -101, Route 100, Morden,MB R6M 1Y5, Canada.* E-mails: elhadrami@cc.umanitoba.ca; daayff@cc.umanitoba.caVerticillium dahliae is known for its widespread around the world; itslongevity and survivability in the soil and its ability to infect a wide host rangeincluding potatoes and sunflowers. This translates into plasticity and flexibility of thepathogen allowing it to infect, grow and develop in presence of its original oralternative hosts. However, that does not occur without a fitness cost and a variationin pathogenicity. V. dahliae cross-pathogenicity was already documented on severalhosts including cotton, mint, lettuce, broccoli, cabbage, cauliflower, strawberry,artichoke, bell and chili pepper, eggplant, potato, tomato, and watermelon. InManitoba (Canada), potato and sunflower growing areas are overlapping and maysometimes be considered in a crop rotation. In the present study, we examined V.dahliae cross-pathogenicity between potato and sunflower using a set of 10 isolatesfrom each host on two potato cultivars (Kennebec, susceptible, and Ranger Russet,moderately resistant) and two sunflower hybrids (IS8048, susceptible, and 6946,moderately resistant). Our results indicated that potato isolates were equallyaggressive on both hosts while isolates from sunflower were better adapted onsunflower than they were on potato, suggesting that rotations when sunflower followspotato should be avoided.69