Association of fungal effectors with pathogenicity of Fusarium oxysporum isolates on soybean.

Fungi within the Fusarium oxysporum species complex (FOSC) can cause root rot, seedling blight, and wilt of soybean. Isolates recovered from soybean vary in aggressiveness and symptoms produced. The goal of this study was to identify a genetic marker to detect aggressive wilt isolates towards soybean. Therefore, the objectives of this study were to screen FOSC isolates with previously described fungal effector; and to determine each isolates ability to produce wilt symptoms on soybean. The fungal effectors Fmk1, Fow1, Pda1, PelA, PelD, Pep1, Prt1, Rho1, Sge1, Six1, Six6, and Snf1 were used to screen 80 isolates within the FOSC collected from soybean roots. Additionally, 27 isolates were screened with the fungal effector Six6 collected from other host, primarily from common bean. The 107 isolates used in this study were tested in the greenhouse for their ability to produce wilt symptoms using susceptible cultivars Jack and/or MN1805. Fmk1, Fow1, PelA, Rho1, Sge1, Six1, Six6, and Snf1 were present in all isolates screened and corresponded to isolate clade based on previous. Pda1, PelD, Pep1, Prt1, Six1, and Six6 were dispersed among isolates. Symptoms of vascular discoloration were observed in 42 isolates. The presence of the Six6 gene correlated with wilt producing isolates suggesting that this gene may be involved in some isolates ability to cause wilt in soybean.