Graduate School of Agriculture, Hokkaido University, Kita-ku Kita 9 Nishi 9, Sapporo, 060-8589, Japan.
Hokkaido Agricultural Research Center, NARO, 1, Hitsujigaoka, Toyohira-ku, Sapporo, Hokkaido, 062-8555, Japan.
Sci Rep. 2021 Mar 18;11(1):6266. doi: 10.1038/s41598-021-85492-z.
Tuber infection of Phytophthora infestans often occurs at harvest. However, it is difficult to accurately estimate the population densities of P. infestans in soil, especially Japanese soil. In the present study, P. infestans DNA was extracted from soil samples using a modified CTAB-bead method and quantified using real-time PCR to accurately, rapidly and easily estimate the P. infestans population densities in upland soils in Japan. P. infestans was well quantified in eleven types of soil samples, including nine types of upland soils in Japan, that were artificially inoculated with a zoosporangia suspension. The amounts of P. infestans DNA estimated by the real-time PCR were proportional to the inoculum densities. In the non-controlled experimental potato field, P. infestans population densities in soil corresponded to the development of symptoms and were correlated with the number of lesions on the potato foliage. These results imply that the proposed real-time PCR assay is suitable for the estimation or monitoring of P. infestans population densities in upland soils in Japan. The population densities at the ridge bottoms were larger than those at any other location in commercial potato fields. These results were similar to those of a previous report using a bioassay. Moreover, a correlation between DNA quantity and inoculum potential was observed. In conclusion, the real-time PCR assay developed in this study is suitable for indirect estimation of the inoculum potential of P. infestans.
马铃薯晚疫病菌的块茎侵染通常发生在收获期。然而，要准确估计土壤，特别是日本土壤中晚疫病菌的种群密度是很困难的。在本研究中，采用改良的 CTAB-珠法从土壤样品中提取晚疫病菌 DNA，并通过实时 PCR 进行定量，以准确、快速和容易地估计日本旱地土壤中晚疫病菌的种群密度。将游动孢子悬浮液人工接种到 11 种土壤样品中，包括日本 9 种旱地土壤，均可很好地定量检测出晚疫病菌。实时 PCR 估计的晚疫病菌 DNA 量与接种密度成正比。在未受控制的实验马铃薯田中，土壤中晚疫病菌的种群密度与症状的发展相对应，并与马铃薯叶片上的病斑数量相关。这些结果表明，所提出的实时 PCR 检测法适用于日本旱地土壤中晚疫病菌种群密度的估计或监测。垄底的种群密度大于商业马铃薯田中任何其他位置的种群密度。这些结果与之前使用生物测定法的报告相似。此外，还观察到 DNA 数量与接种体潜力之间的相关性。总之，本研究中开发的实时 PCR 检测法适用于间接估计晚疫病菌接种体潜力。
