|LEBEDA, ALEŠ - Palacky University|
|KRÍSTKOVÁ, EVA - Palacky University|
|SEDLÁKOVÁ, BOŽENA - Palacky University|
|McCreight, James - Jim|
|KOSMAN, EVSEY - Tel Aviv University|
Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2018
Publication Date: 3/28/2018
Citation: Lebeda, A., Krístková, E., Sedláková, B., Mccreight, J.D., Kosman, E. 2018. Virulence variation of cucurbit powdery mildews in the Czech Republic – population approach. European Journal of Plant Pathology. 1-18. https://doi.org/10.1007/s10658-018-1476-x.
Interpretive Summary: Powdery mildew of cucurbits, which is incited by two airborne fungi, Golovinomyces orontii (Go) and Podosphaera xanthii (Px), adversely effects cucurbit production worldwide through loss of fruit yield and quality (sweetness, flavor). This study applied diversity analysis to patterns of diseases caused by 115 isolates of the two fungi from the Czech Republic collected from 2010 through 2012 on a set of 21 melon varieties selected for their reactions to cucurbit powdery mildew. Golovinomyces orontii consistently occurred earlier in the season than Px, but by the end of the each growing season Px was the dominant fungus on cucurbits. The study examined the relationships between the ability of the two fungi to incite disease (virulence) and their geographic origins and host cucurbit species from which they were collected. There were no significant differences between Go isolates from different host plant species due to the high variability among Go isolates, but there were significant host-specific differences among Px isolates. Relationships among selected Go isolates based on virulence differences were similar to those reported in a previous analysis based on molecular markers. Diversity analysis of virulence patterns provides a complex view of virulence structures of cucurbit powdery mildew populations, and when completed by race determination and denomination on melon, it may serve as a base for understanding virulence variation of these two cucurbit powdery mildew species from different origins and years.
Technical Abstract: Kosman diversity models were applied to analyses of virulence (disease reaction patterns) variation of 115 isolates of two cucurbit powdery mildew (CPM) species, Golovinomyces orontii (Go) and Podosphaera xanthii (Px), collected in the Czech Republic from 2010 through 2012. Diversity within and distances between Go and Px populations and each other in spatio-temporal context and with regard of original host plant species were analyzed, based on virulence patterns of individual isolates (races) on a set of 21 melon (Cucumis melo L.) race differential genotypes. Significant differentiation among the Go and Px pathogen populations was revealed, and the results clearly demonstrate and confirm that the set of differential C. melo genotypes is well composed because of high differentiation capacity. Differentiation of pathogens among years was significant for both species. No significant difference between Go isolates from different host plant species was established due to high variability among Go isolates, but there was significant host-specific differentiation among Px isolates. Differentiation of pathogens among regions was not detected. These results revealed high virulence variation in isolates of Go and Px, and their spatio-temporal fluctuations. High diversity in virulence of Go isolates supports the treatment of Go as a complex of different (sub)species with distinct virulence factors. Similar relationships of selected Go isolates in a UPGMA dendrogram in a previously reported multigene phylogenetic tree support the logic and suitability of the Kosman assignment based approach to population studies of organisms with asexual or mixed modes of reproduction. Approach applied in this study provides a complex view of virulence structures of powdery mildew populations, and when completed by race determination and denomination on melon, it may serve as a base to understand virulence variation of these CPM species from a spatio-temporal viewpoint.