Abstract
BackgroundEarly blight, caused by the fungus Alternaria solani, occurs on potato mainly in the south-eastern part of Sweden, but also in other parts of the country. The aim of this study was to investigate the genetic diversity of A. solani populations from different potato growing regions in south-eastern Sweden using AFLP marker analysis. In addition, the cultured isolates were examined for substitutions in the gene encoding cytochrome b, associated with loss of sensitivity against QoI fungicides.ResultsNei's gene diversity index for the Swedish populations of A. solani revealed a gene diversity of up to 0.20. Also genetic differentiation was observed among populations of A. solani from different locations in south-eastern Sweden. The mitochondrial genotype of the isolates of A. solani was determined and both known genotypes, GI (genotype 1) and GII (genotype 2), were found among the isolates. The occurrence of the F129L substitution associated with a loss of sensitivity to strobilurins was confirmed among the GII isolates. In vitro conidial germination tests verified that isolates containing the F129L substitution had reduced sensitivity to azoxystrobin and, at a lower extent, to pyraclostrobin.ConclusionsGenetic diversity was relatively high among isolates of A. solani in south-eastern part of Sweden. F129L substitutions, leading to reduced sensitivity to strobilurins, have been established in field populations, which may have implications for the future efficacy of QoI fungicides.
Highlights
Blight, caused by the fungus Alternaria solani, occurs on potato mainly in the south-eastern part of Sweden, and in other parts of the country
Both A. solani and A. alternata have been detected in the field, but A. solani was found more often [6]
Further investigations confirmed that early blight in south-eastern Sweden is mainly caused by A. solani [7]
Summary
Blight, caused by the fungus Alternaria solani, occurs on potato mainly in the south-eastern part of Sweden, and in other parts of the country. Blight is a common fungal disease in Swedish potato fields and during the last decade a number of reports have stressed that the disease is an increasing problem in the south-eastern part of the country, especially in starch potato crops. Both A. solani and A. alternata have been detected in the field, but A. solani was found more often [6]. Further investigations confirmed that early blight in south-eastern Sweden is mainly caused by A. solani [7]
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