Understanding pathogen population structure and virulence variation for efficient resistance breeding to control cucurbit powdery mildews

Abstract

Cucurbit powdery mildew (CPM) is caused most frequently by well-differentiated obligate erysiphaceous ectoparasites Golovinomyces orontii and Podosphaera xanthii, which vary in their ecology and virulence. All economically important cucurbit crops host both of these CPM species. Breeding of cucurbits for CPM resistance is highly important worldwide, but adequate knowledge of CPM species determination, as well as virulence structure, population dynamics, and spatiotemporal variation of these pathogens, has not yet been achieved. New tools have been developed to enhance research on CPM virulence variation for more efficient breeding and seed and crop production. A set of differential genotypes of Cucumis melo, with high differentiation capacity, may contribute substantially to understanding of variation in CPM virulence at both individual and population levels. Long-term observations (2001-2012) of CPM pathogens in the Czech Republic were used to analyse virulence variation within and among annual CPM populations and demonstrate the utility of recently developed tools for studying species variability and virulence variation of CPM pathogens worldwide. Detailed analyses of diversity and spatiotemporal fluctuations in the composition of CPM populations provide crucial information for shaping breeding programmes and predicting the most effective sources of race-specific resistance. The primary aim of this work was to create a uniform framework for determination of CPM species structure and diversity, virulence phenotypes, virulence and phenotype frequencies, phenotype complexity, dynamics, and variation within and among CPM populations.

Hyperparasitic Fungi against Melon Powdery Mildew Pathogens: Quantitative Analysis of Conidia Released from Single Colonies of Podosphaera xanthii Parasitised by Ampelomyces

“…Growers spray fungicides before or after PM colonies appear on host leaves, to control disease. However, frequent application can cause resistance to commercial fungicides in the fungi causing PM, as shown in diseased cucurbit plants [16][17][18][19][20][21][22]. To avoid fungicide resistance and environmental problems caused by fungicide residues, new control strategies that are independent of chemical methods are needed to control PM.…”

Advanced Genetic Studies on Powdery Mildew Resistance in TGR-1551

“…The occurrence of CPM early in the growing season can lead to a massive reduction in photosynthetic capacity, with negative impacts on plant growth and development, as well as fruit quality [ 2 , 3 , 4 ]. Two ectoparasites, Golovinomyces orontii ( Go ) and Podosphaera xanthii ( Px ), are economically important and distributed worldwide [ 5 ], as they are both the two most commonly reported causal agents of CPM [ 6 , 7 ].…”

The co‐occurrence of two powdery mildew species on Cannabis sativa in the Czech Republic

“…This is related to the temperature requirements of both species (e.g. Křístková et al., 2009; Lebeda et al., 2009, 2021). Punja (2022) compared the conditions needed for successful development of individual powdery mildew species infecting cannabis in Canada (British Columbia); while G. ambrosiae was present exclusively on greenhouse grown cannabis plants, P. macularis was identified on plants grown outdoors.…”