Tag Archives: virulence testing.

220–227 E. Runno-Paurson, R. Kiiker, A. Aav, M. Hansen and I.H. Williams
Distribution of mating types, metalaxyl sensitivity and virulence races of Phytophthora infestans in Estonia
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Distribution of mating types, metalaxyl sensitivity and virulence races of Phytophthora infestans in Estonia

E. Runno-Paurson*, R. Kiiker, A. Aav, M. Hansen and I.H. Williams

Estonian University of Life Sciences, Institute of Agricultural and Environmental
Sciences, Department of Plant Protection, Kreutzwaldi 1, EE51014 Tartu, Estonia
*Correspondence: eve.runno-paurson@emu.ee

Abstract:

 Potato late blight, caused by the oomycete Phytophthora infestans, is a destructive potato disease, causing considerable crop loss worldwide. As the late blight pathogen population is diverse and variable in Estonia, changes in the population should be monitored regularly. In this study, the Estonian population of P. infestans was characterised with mating type, sensitivity to metalaxyl and virulence on potato R-gene differentials. During the growing season 2013, 110 isolates were collected from nine potato fields. The frequency of A2 mating type was on average 29%, and varied significantly between different fields from 7% to 78% (p = 0.001). On all studied potato fields, both mating types were recorded, suggesting continuous sexual  reproduction of P. infestans and possible risk of oospore production and early attacks of late blight in Estonian potato fields. The prevalence of metalaxyl sensitive isolates in the population (64%) differed from results from previous research. Thus changes have occurred in the P. infestans Estonian population. There were no significant differences in metalaxyl sensitivity between studied fields (p = 0.073). The Estonian race structure was highly diverse and complex, on average 7.2 virulence factors per isolate, but varied between fields from 5.6 to 9.0. 42 virulence races were found; the four most common were 1.2.3.4.5.6.7.8.10.11, 1.2.3.4.6.7.8.10.11, 1.2.3.4.7.10.11 and 1.2.3.4.7.8.10.11, which comprised 46% of the population. The overall normalized Shannon’s diversity index was 0.69, confirming the high diversity of the population. Continuous pathogen population studies describing the contemporary P. infestans population are essential in order to advise potato breeders and growers accordingly.

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