Genetic and molecular landscapes of the generalist phytopathogen Botrytis cinerea

Botrytis cinerea Pers. Fr. (teleomorph: Botryotinia fuckeliana) is a necrotrophic fungal pathogen that attacks a wide range of plants. This updated pathogen profile explores the extensive genetic diversity of B. cinerea, highlights the progress in genome sequencing, and provides current knowledge of genetic and molecular mechanisms employed by the fungus to attack its hosts. In addition, we also discuss recent innovative strategies to combat B. cinerea.

TAXONOMY

Kingdom: Fungi, phylum: Ascomycota, subphylum: Pezizomycotina, class: Leotiomycetes, order: Helotiales, family: Sclerotiniaceae, genus: Botrytis, species: cinerea.

HOST RANGE

B. cinerea infects almost all of the plant groups (angiosperms, gymnosperms, pteridophytes, and bryophytes). To date, 1606 plant species have been identified as hosts of B. cinerea.

GENETIC DIVERSITY

This polyphagous necrotroph has extensive genetic diversity at all population levels shaped by climate, geography, and plant host variation.

PATHOGENICITY

Genetic architecture of virulence and host specificity is polygenic using multiple weapons to target hosts, including secretory proteins, complex signal transduction pathways, metabolites, and mobile small RNA.

DISEASE CONTROL STRATEGIES

Efforts to control B. cinerea, being a high-diversity generalist pathogen, are complicated. However, integrated disease management strategies that combine cultural practices, chemical and biological controls, and the use of appropriate crop varieties will lessen yield losses. Recently, studies conducted worldwide have explored the potential of small RNA as an efficient and environmentally friendly approach for combating grey mould. However, additional research is necessary, especially on risk assessment and regulatory frameworks, to fully harness the potential of this technology.

Characterization of Botrytis cinerea Isolates From Grape Vineyards in China

One hundred thirty-five single-spore isolates were collected from grape vineyards from 15 provinces or autonomous regions belonging to five viticulture climatic zones in China. All the isolates were identified as Botrytis cinerea based on their morphological and molecular characters. The 135 isolates were all heterothallic isolates. Seventy-one isolates belonged to the MAT1-1 type and 64 were characterized to MAT1-2 type. All the isolates studied belonged to Group II based on PCR-RFLP of the Bc-hch locus. The four TE genotypes, transposa, Boty-only, Flipper-only, and vacuma, comprised 51.9%, 33.3%, 10.4%, and 4.5%, respectively, of the total population. The frequency of transposa was highest in the total population and the most of any subpopulation (each viticulture climatic zone), and Boty-only was highest in warm areas (46.2%). Vacuma was mainly distributed in northern China, although in small amounts, and Flipper-only was mainly was distributed in humid tropical areas (42.9%). A microsatellite analysis of B. cinerea populations was performed to assess the genetic population structure. A total of 127 different MLGs were identified among 135 B. cinerea isolates, with a genotypic diversity of 0.9991. The transposa population isolates showed higher genetic diversity than other populations. Pairwise tests of genetic differentiation among four TE-type populations yielded generally low to high Gst values. All isolates belonged to two genetic clusters. The population microsatellite diversity and genetic structure had a certain correlation with the TE type and geographic origin. This is the first report of the genotypic diversity of B. cinerea isolates from grape vineyards across China.