Grey mould is reported in the vineyards of Castilla y León, Spain, every year. However, the natural populations of the pathogen have yet to be properly characterized. Vineyards from six wine‐producing areas were surveyed in 2002 and 2007, sampling from bunches of grapes with and without symptoms. A total of 283 Botrytis field isolates were selected for physiological and genetic analyses. Botrytis cinerea isolates predominated in the population, although isolates belonging to Botrytis pseudocinerea and Botrytis prunorum were also identified. These two species are recorded for the first time in Spain in this work. In addition, two isolates closely related to Botrytis californica were identified. Physiologically, the B. cinerea population is very diverse, displaying a normal distribution of aggressiveness values in Vitis vinifera leaves, suggesting a quantitative nature for this trait. Several isolates unable to cause infection were identified, most of them belonging to a mycelial morphotype. Population genetic analysis revealed that genotypic diversity is high and that multiple infections of the same bunch of grapes by different genotypes occur frequently. The high genotypic diversity observed, an even distribution of both mating types and the linkage disequilibrium values detected support a mixed mode of reproduction with low levels of clonality. The wine‐producing area in which each isolate was collected imposed a low degree of population differentiation, an effect that does not depend solely on the geographic distances but rather on the management practices used by growers and wine producer associations.

Botrytis cinerea is a necrotrophic plant pathogenic fungus with a wide host range. Its natural populations are phenotypically and genetically very diverse. A survey of B. cinerea isolates causing gray mold in the vineyards of Castilla y León, Spain, was carried out and as a result eight non-pathogenic natural variants were identified. Phenotypically these isolates belong to two groups. The first group consists of seven isolates displaying a characteristic mycelial morphotype, which do not sporulate and is unable to produce sclerotia. The second group includes one isolate, which sporulates profusely and does not produce sclerotia. All of them are unresponsive to light. Crosses between a representative mycelial non-pathogenic isolate and a highly aggressive field isolate revealed that the phenotypic differences regarding pathogenicity, sporulation and production of sclerotia cosegregated in the progeny and are determined by a single genetic locus. By applying a bulked segregant analysis strategy based on the comparison of the two parental genomes the locus was mapped to a 110 kb region in chromosome 4. Subcloning and transformation experiments revealed that the polymorphism is an SNP affecting gene Bcin04g03490 in the reference genome of B. cinerea. Genetic complementation analysis and sequencing of the Bcin04g03490 alleles demonstrated that the mutations in the mycelial isolates are allelic and informed about the nature of the alterations causing the phenotypes observed. Integration of the allele of the pathogenic isolate into the non-pathogenic isolate fully restored the ability to infect, to sporulate and to produce sclerotia. Therefore, it is concluded that a major effect gene controlling differentiation and developmental processes as well as pathogenicity has been identified in B. cinerea. It encodes a protein with a GAL4-like Zn(II)2Cys6 binuclear cluster DNA binding domain and an acetyltransferase domain, suggesting a role in regulation of gene expression through a mechanism involving acetylation of specific substrates.

THE CLASSICAL REVIEW xi. didicerunt (14), regnaverunt (24). xii. abstulerunt (18). xiii. detulerunt (43). xiv. exoleverunt (21), praeduxerunt (32), fuerunt (44), tenuerunt (55). xv. pepererunt (20), acciderunt (38), amiserunt (46), sumpserunt (49), crediderunt (52). xvi. steteruntque (30).

IntroductionMediterranean forests are currently facing a surge in abiotic stressors such as droughts and massive fires as a result of climate crisis and human pressure. Susceptibility to biotic stressors has also increased, including a variety of pests and pathogens capable of weakening and potentially killing forest flora. Biodiversity of microbiome protects forests against declines as it increases trees’ resilience and adaptability.ObjectivesWith the objective of analyzing the relationship between health status and fungal diversity, in the present work the mycobiota of declined and healthy specimens of keystone Mediterranean tree species is described and compared.MethodsTo this end, bark and wood from declining Spanish forests of Castanea sativa (chestnut), Quercus ilex (holm oak), Quercus suber (cork oak), and Quercus pyrenaica (pyrenean oak) were sampled and the Internal Transcribed Spacer (ITS1) genomic region was sequenced.ResultsResults showed a predominance of Ascomycota, Basidiomycota, and Mucoromycota in all samples. Alpha diversity at genus level was not affected by health status and was characterized by uneven, poorly distributed fungal communities dominated by a few genera. Differentially abundant (DA) genera between healthy and declined samples were found in chestnut (15), holm oak (6), and pyrenean oak (4) trees, but not in cork oak. Some genera known for their plant protection potential, such as Trichoderma, were found exclusively in healthy trees. Functional profiles revealed a predominance of phytopathogens and saprobes in all tree species, irrespective of their health status.DiscussionThis study emphasizes the importance of Mediterranean forests as biodiversity refuges and highlights the value of above-ground tissues as a valid approach to assess shifts in forests’ microbiome diversity in response to biotic and abiotic stressors.

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