|DOAN, HUNG - University Of California|
|Bell, Alois - Al|
|DAVIS, R - University Of California|
|Stipanovic, Robert - Bob|
|NICHOLS, ROBERT - Cotton, Inc|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2015
Publication Date: 11/2/2015
Citation: Crutcher, F.K., Doan, H.K., Bell, A.A., Davis, R.M., Stipanovic, R.D., Nichols, R.L., Liu, J. 2015. Evaluation of methods to detect the cotton pathogen Fusarium oxysporum f. sp. vasinfectum race 4. American Phytopathological Society Abstracts. 105:S4.31.
Technical Abstract: Fusarium wilt caused by Fusarium oxysporum f. sp. vasinfectum (Fov) is an important disease of cotton. Fov race 4, identified in the San Joaquin Valley of California, has caused serious losses and is a potential threat to US cotton production. Tests have been developed to rapidly identify race 4 in the laboratory and the field. These tests were evaluated on a panel of 35 Fov isolates from a USDA Insect Control and Cotton Disease Research Unit collection that represented distinct races, genotypes, and origins. Two different PCR protocols have been published. Screening the isolate panel with one of the protocols resulted in correct identifications, with the exception of one isolate that has not been found in US cotton. The second PCR protocol had several false positives that may have resulted from using a low annealing temperature. Another method, a commercial kit, was also tested on genomic DNA, fungal tissue, and infected plant tissue. The use of genomic DNA resulted in 12 false positives with the kit. The strain that gave the exceptional reading in the PCR screen also produced a false positive when tested on fungal and infected plant tissues using the kit. The presentation will clarify limitations of current protocols for identification of Fov race 4. Such diagnostic technology is essential for the prevention of further spread of Fov 4 within California and preventing its movement across US cotton production areas.