How do Japanese isolates of Verticillium dahliae correspond with standardized VCG testers?

Abstract

We examined the vegetative compatibility of 56 Japanese isolates provisionally assigned to four subgroups of V, dahliae to estimate the genetic relatedness with testers of the standardized VCGs. Subgroup J1 was assigned to VCG 2A/B as a new category of assignment. Subgroup J2, except isolate Vdt 110, was assigned to VCG 2A, and subgroup J3, except isolate Vdf 1, was assigned to VCG 2B. Isolates Vdf 1 and Vdt 110 were assigned to VCG 2A/B. Subgroup J4 was assigned to two subgroups, VCG 4B for Vde 1 and VCG 4A/B for FY 3 and HR 1. Four isolates were compatible with both VCG 2 and 4. Isolate U56 was compatible with VCG 2A/B and 4A. Isolates of VCG 2A, Vdt 9 and FF 1, were compatible with either VCG 4A or 4A/B. One isolate of VCG 2B, Vdp-4, was compatible with VCG 4A. Three isolates of subgroup J2 showed weak reactions with the testers of VCG 4. These isolates may be "bridging strains". Japanese isolates were composed of two VCGs, 2 and 4, "bridging strains" compatible with these VCGs, and some self-incompatible isolates. Testers of VCG 1 and VCG 3 did not show any reactions with the Japanese isolates.Key Words bridging strain; pathotype; standardized tester; VCG; Verticillium dahliae.Verticillium dahliae Kleb. is one of the important soilborne fungal plant pathogens. It infects a wide range of crops. As the pathogenicity depends upon the isolate (Bewley, 1922;Kendrick and Middleton, 1959), inoculation tests are required to determine the pathogenicity. In Japan, a differential host method has been proposed (lijima, 1983) and improved to determine certain host ranges (Hagiwara, 1990;Horiuchi et al., 1990;Suwa et al., 1987). However, this differential host method has not proven conclusive. Over time, as new differential hosts were used for the pathogenicity test, new categorizations resulted (lijima, 1983;Takeda et al., 1988). Recently, V, dahliae race-2 of tomato wilt (Kobayashi et al., 1989) and tomato-pepper pathotype of V. dahliae (lijima, 1983;Oshima et al., 1993) appeared as new diseases in Japan. Now, determination of pathotypes of V. dahliae has become quite complicated using the differential host method.On the other hand, genetic relatedness in fungi can be estimated by their vegetative compatibility (Glass and Kuldau, 1992;Leslie, 1993 Puhalla and Hummel (1983). By this method, the number of distinct VCGs was reduced from 16 to 4. Several authors have followed this system (Bao et al., 1998;Daayf et al., 1995;Dobinson et al., 1998;Elena, 1997;Korolev, et al., 1997aKorolev, et al., , 1997bRataj-Guranowska and Hiemsta, 1997;Strausbaugh et al., 1992;Strausbaugh, 1993). It should be emphasized that the method used in VCG analysis can affect the results significantly (Rowe, 1995).Evaluation of weak reactions led to subdivisions of VCGs 2 and 4. Joaquim and Rowe (1991) discussed differential reactions among isolates of VCG 2 but avoided the subdivision of this VCG in order to keep their VCG system for V. dahliae as simple as possible. In the case of VCG 4, three subgroups (4A, 4B, and 4A/B) were proposed to accomod...

Genetic relationships between virulence, vegetative compatibility and ISSR marker ofVerticillium dahliaeisolated from cotton

“…VCG 1 was noted among isolates from potatoes (USA), olive (defoliating-type isolates) (Spain), cotton (USA, Spain, Greece) and artichoke (Spain). VCG 1 has not been identified in Northern countries like Netherlands (Hiemstra & Rataj-Guranowska 2003), Poland (Rataj-Guranowska et al 2002) or Germany (Zeise & Von Tiedemann 2002) or in Europe and Canada (Dobinson et al 1998) or Japan (Ebihara et al 1999).…”

Variation in genotype, pathotype and anastomosis groups of Colletotrichum lindemuthianum isolates from Mexico

“…A diversity index of 2·15 was calculated for the Chihuahua samples over the 2 years (Table 1). All isolates were tested for anastomosis and determined to belong to a single anastomosis group and two pathotypes: race 449 (1998) infecting Chihuahua, Michoacán (1998/1999) and Mexico State (1998. The sample number, location and year of collection are indicated.…”

“…This is the first report concerning anastomosis groups in C. lindemuthianum and demonstrates that in natural populations several anastomosis groups can be identified, suggesting that this may be an important mechanism leading to the formation of clonal lineages of C. lindemuthianum . Isolate Mi.7·99 is interesting as it is capable of carrying out anastomosis with isolates from both anastomosis groups 4 and 5, and could be a so‐called ‘bridge’ strain which allows exchange of genetic information between the two anastomosis groups (Ebihara et al ., 1999). The other possibility is that Mi.7·99 is a mixed culture.…”