TY - JOUR
T1 - Genetic diversity, anastomosis groups and virulence of Rhizoctonia spp. from strawberry
AU - Sharon, Michal
AU - Freeman, Stanley
AU - Kuninaga, Shiro
AU - Sneh, Baruch
N1 - Funding Information:
The authors are grateful to Takeda Chemical Industries Ltd., Osaka, Japan, for generously providing the TNP-470. This work was partially supported by grants from Mapfre-Medicine Foundation, FIS 98/1018, and CAM 8.1/11/97.
PY - 2007/3
Y1 - 2007/3
N2 - Virulent Rhizoctonia spp. isolated from strawberry in Israel belonged to anastomosis groups (AG) of: binucleate Rhizoctonia (BNR) AG-A, AG-G, AG-K and AG-F, and to multinucleate Rhizoctonia (MNR) AG 4 subgroup HG-I. In addition, a soil isolate of AG 4 subgroup HG-III was also found to be virulent on strawberry. None of the Israeli isolates obtained in the present study belonged to BNR AG-I, or other MNR AGs. In the cluster analysis of rDNA-ITS sequences, all of the isolate sequences consistently clustered according to their known AGs and subgroups. One AG-F cluster included sequences of 10 strawberry isolates, while another AG-F cluster included sequences of two isolates submitted to GenBank. Additional work is needed to determine whether the isolates of these two clusters may belong to different AG-F subgroups. The current virulence bioassay used for Rhizoctonia spp. isolates on strawberry is based on inoculation of stolon-derived daughter plants with the isolates and estimation of the reduction in plant biomass, rather than on specific distinct disease severity symptoms. The duration of this test is relatively long (ca. 5 weeks or more) and the availability of daughter plants from runners is naturally limited to a certain season. Among the possible alternative methods evaluated in the present study (inoculation of fruits or seedlings developed from germinated strawberry seeds), the method based on seedlings was best. This method has a potential to replace the currently used stolon-daughter plant inoculation bioassay for testing virulence of strawberry root pathogens. This is the first report indicating that Rhizoctonia spp. isolates that belong to AG-F, AG-K, AG 4 HG-I and AG 4 HG-III are virulent to strawberry.
AB - Virulent Rhizoctonia spp. isolated from strawberry in Israel belonged to anastomosis groups (AG) of: binucleate Rhizoctonia (BNR) AG-A, AG-G, AG-K and AG-F, and to multinucleate Rhizoctonia (MNR) AG 4 subgroup HG-I. In addition, a soil isolate of AG 4 subgroup HG-III was also found to be virulent on strawberry. None of the Israeli isolates obtained in the present study belonged to BNR AG-I, or other MNR AGs. In the cluster analysis of rDNA-ITS sequences, all of the isolate sequences consistently clustered according to their known AGs and subgroups. One AG-F cluster included sequences of 10 strawberry isolates, while another AG-F cluster included sequences of two isolates submitted to GenBank. Additional work is needed to determine whether the isolates of these two clusters may belong to different AG-F subgroups. The current virulence bioassay used for Rhizoctonia spp. isolates on strawberry is based on inoculation of stolon-derived daughter plants with the isolates and estimation of the reduction in plant biomass, rather than on specific distinct disease severity symptoms. The duration of this test is relatively long (ca. 5 weeks or more) and the availability of daughter plants from runners is naturally limited to a certain season. Among the possible alternative methods evaluated in the present study (inoculation of fruits or seedlings developed from germinated strawberry seeds), the method based on seedlings was best. This method has a potential to replace the currently used stolon-daughter plant inoculation bioassay for testing virulence of strawberry root pathogens. This is the first report indicating that Rhizoctonia spp. isolates that belong to AG-F, AG-K, AG 4 HG-I and AG 4 HG-III are virulent to strawberry.
KW - Black root rot
KW - Daughter plants
KW - Fragaria ananassa
KW - Hard rot
KW - Percent sequence similarity
KW - Rhizoctonia praticola
KW - Virulence tests
KW - rDNA-ITS sequence analysis
UR - http://www.scopus.com/inward/record.url?scp=33846865756&partnerID=8YFLogxK
U2 - 10.1007/s10658-006-9091-7
DO - 10.1007/s10658-006-9091-7
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AN - SCOPUS:33846865756
SN - 0929-1873
VL - 117
SP - 247
EP - 265
JO - European Journal of Plant Pathology
JF - European Journal of Plant Pathology
IS - 3
ER -