| Late blight, caused by the oomycete Phytophthora infestans, has been the most devastating diseases of potato (Solanum tuberosum) in the world. Analysis of the population genetic variation of P. infestans is essential for understanding the disease epidemiology and developing disease control measures. A range of molecular genetic markers including Simple Sequence Repeat (SSR), have been widely used for studying genetic variation and differentiation of pathogen populations. In this study, mating type determination and a set of 6 SSR markers were used for assess genetic diversity of P. infestans population in a germplasm nursery in Southern Ningxia.Current strategies for the control of potato late blight are highly dependent on spraying application of fungicides. In this study, fungicide treatment of potato seed tubers was employed to assess the field efficacies of three different, commonly used fungicides, at two different concentrations on the control of potato late blight.The results are as follows:1. A total of 128 isolates were collected from 57 infected potato lines in a germplasm nursery in the Southern Ningxia.2. Of 128 collected isolates, 116 were dectermined for mating types. The majority isolates (67, 53.3%) were A2 mating type, followed by A1 mating type (28, 21.9%), and 21 isolates were determined to be self-fertile.3. Using 6 SSR markers, 38 genotypes were detected among 128 P. infestans isolates. Two genotypes were found to be dominant, comprising 33 and 26 isolates, respectively, and were collected from 48 potato lines. P. infestans isolates of different genotypes were isolated from the same potato lines. Isolates of unique genotypes were detected from many potato lines.4. The soaking treatment of seed tubers with the 50% dimethomorph WP at 350x dilution achieved the best efficiency against late blight in terms of lower percentage of diseased plants, fewer and light diseased leaf tissues. |
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