Jump to Main Content
Evaluation of methods to detect the cotton wilt pathogen Fusarium oxysporum f. sp. vasinfectum race 4
- Crutcher, Frankie K., Doan, Hung K., Bell, Alois A., Davis, R. Michael, Stipanovic, Robert D., Nichols, Robert L., Liu, Jinggao
- European journal of plant pathology 2016 v.144 no.1 pp. 225-230
- Fusarium oxysporum f. sp. vasinfectum, Fusarium wilt, Gossypium barbadense, Gossypium hirsutum, cotton, crop production, diagnostic techniques, fungi, genes, genotype, mycelium, pathogens, plant tissues, planting, polymerase chain reaction, races, soil, California
- Fusarium wilt, caused by Fusarium oxysporum f. sp. vasinfectum (Fov), is an economically important disease of cultivated cottons (Gossypium hirsutum and G. barbadense). Recently, Fov race 4 has spread among soils planted to cotton in the San Joaquin Valley of California causing significant losses. Because Fov 4 is seedborne and persists in infested soils, it is a potential threat to all US cotton production regions. Tests have been developed to rapidly identify race 4 in the laboratory and the field, including a race 4 specific PCR and a test kit for use with fungal mycelium and infected plant tissue. Currently, the test kit is the only available method to identify race 4 in the field. Both the PCR and kit tests were evaluated on a panel of 36 Fov isolates that represented all described races and many genotypes from several geographic regions. As expected, race 4 isolates gave positive reactions, as did race 7 isolates. One race 7 isolate was not vegetatively compatible with the race 4 isolates, while the other isolate of race 7 exhibited a compatible reaction. Isolates of race 7 and race 4 have identical partial sequences in three nuclear genes. In addition, the type isolate of race 3 gave a positive reaction. All other isolates, including the highly-virulent Australian isolates, were negative. The diagnostic tests clearly distinguished race 4 from races 1, 2, 6, and 8 but not from the race 3 and race 7 isolates tested here. Race 3 and 7 are similar in etiology to that of race 4, thus a method is needed to distinguish these in the field.