Striking Similarities Between Botrytis cinerea From Non-agricultural and From Agricultural Habitats

Abstract

Investigations into life history of microorganisms that cause plant diseases have been limited mostly to contexts where they are in interaction with plants, and with cropped or otherwise managed vegetation. Therefore, knowledge about the diversity of plant pathogens, about potential reservoirs of inoculum and about the processes that contribute to their survival and adaptation is limited to these contexts. The agro-centric perspective of plant pathogen life histories is incoherent with respect to the capacity of many of them to persist as saprophytes on various substrates. In this context we have investigated the ubiquity of the broad host range necrotrophic fungus Botrytis cinerea, outside of agricultural settings and have determined if the populations in these natural habitats can be distinguished phenotypically and phylogenetically from populations isolated from diseased crops. Over a period of 5 years, we isolated B. cinerea from 235 samples of various substrates collected in France including rainfall, snowpack, river, and lake water, epilithic biofilms in mountain streams, leaf litter and plant debris, rock surfaces, bird feathers and healthy wild plants from outside of agricultural fields. All substrates except rock surfaces harbored B. cinerea leading us to establish a collection of purified strains that were compared to B. cinerea from diseased tomato, grapes and various other crops in France. Phylogenetic comparisons of 321 strains from crop plants and 100 strains from environmental substrates based on sequences of 9 microsatellite markers revealed that strains from crops and the environment could not be distinguished. Furthermore, the genetic diversity of strains outside of agriculture was just as broad as within agriculture. In tests to determine the aggressiveness of strains on tomato stems, the mean disease severity caused by strains from environmental substrates was statistically identical to the severity of disease caused by strains from tomato, but was significantly greater than the severity caused by strains from grape or other crops. Our results suggest that highly diverse populations of this plant pathogen persist outside of agriculture in association with substrates other than plants and that this part of their life history is compatible with its capacity to maintain its potential as plant pathogen.

Fungal Evolution in Anthropogenic Environments: Botrytis cinerea Populations Infecting Small Fruit Hosts in the Pacific Northwest Rapidly Adapt to Human-Induced Selection Pressures

“…We have not assessed effective population size of B. cinerea in this study, but large effective population sizes were reported before (61). Moreover, the ubiquity and high genetic diversity of B. cinerea were confirmed by analyzing strains from agricultural and nonagricultural habitats in France, suggesting large population sizes that retain their pathogenic potential even without association with hosts (58). Therefore, we conclude that inconsistent population differentiation at a farm scale is most likely caused by local adaptation to anthropogenic factors, such as cropping systems and/or management strategies (4).…”

Quantitative interactions: the disease outcome of Botrytis cinerea across the plant kingdom

“…An analysis of known ( Elad et al 2016 ) hosts showed that the eudicots contain 71% of the plant species with documented Botrytis disease symptoms, currently 996 species are widely spread across orders ( Figure 1 ). B. cinerea has extensive standing genetic variation in both local and global populations ( Ma and Michailides 2005 ; Calpas et al 2006 ; Atwell et al 2015 , 2018 ; Walker et al 2015 ; Bardin 2018 ). In addition, B. cinerea spores are airborne and widespread within the environment ranging from presence on plants to presence on nonplant substrates including within rain, indicating an ability to spread rapidly and widely ( Leyronas et al 2015a ; Bardin 2018 ).…”

The bud rot pathogens infecting cannabis (Cannabis sativa L., marijuana) inflorescences: symptomology, species identification, pathogenicity and biological control

“…The genus Botrytis contains up to 38 recognized species which differ in biology, morphology and host range and can be distinguished using a range of molecular approaches (Staats et al 2005;Garfinkel et al 2019;Garfinkel 2021). Botrytis cinerea is the most widespread generalist species, causing grey mould on over 1400 plant species (Garfinkel et al 2019;Kozhar et al 2020;Garfinkel 2021) and it is commonly found in both agricultural and nonagricultural environments (Bardin et al 2018) and is prevalent in greenhouses (Hausbeck and Pennypacker 1991;Carisse and van der Heyden 2015). Pathogen populations tend to be genetically diverse with little evidence for host specialization (Kozhar et al 2020).…”