A Novel Seimatosporium and Other Sporocadaceae Species Associated with Grapevine Trunk Diseases in Cyprus.

Besides well-known grapevine trunk disease (GTD)-related pathogens, there is an increased interest in wood-colonizing fungi that infect grapevines. During 2017-2018, a survey was conducted in Cyprus and wood samples were collected from vines exhibiting typical GTD symptoms. Based on morphological and multilocus phylogenetic analyses (ITS, LSU, bt2, tef1-a), four species in the Sporocadaceae family were described and typified; two in the genus of Seimatosporium: Seim. cyprium sp. nov. and Seim. vitis-viniferae and two in Sporocadus: Spo. kurdistanicus and Spo. rosigena. The teleomorph of Seim. cyprium sp. nov. was also described. Pathogenicity trials with representative isolates of each species were performed on woody stems of two-year-old potted grapevines for 12 months under field conditions. All isolates were pathogenic, causing dark brown to black vascular discoloration, extending upward and downward from the inoculation point. Sporocadus isolates were significantly more aggressive than Seimatosporium with lesion lengths ranging from 9.24 to 6.90 and 4.13 to 4.00 cm, respectively. Successful re-isolations were also evident for all species and isolates. Seim. cyprium sp. nov. is a newly described species, while Spo. kurdistanicus and Spo. rosigena are reported for the first time in Europe on Vitis vinifera, suggesting the potential role of Sporocadaceae in the GTDs complex.

Under Pressure: A Comparative Study of Botrytis cinerea Populations from Conventional and Organic Farms in Cyprus and Greece.

The highly heterogeneous nature of Botrytis cinerea provides adaptive benefits to variable environmental regimes. Disentangling pathogen population structure in anthropogenic agroecosystems is crucial to designing more effective management schemes. Herein, we studied how evolutionary forces exerted in different farming systems, in terms of agrochemicals-input, shape B. cinerea populations. In total, 360 B. cinerea isolates were collected from conventional and organic, strawberry and tomato farms in Cyprus and Greece. The occurrence and frequency of sensitivities to seven botryticides were estimated. Results highlighted widespread fungicide resistance in conventional farms since only 15.5% of the isolates were sensitive. A considerable frequency of fungicide-resistant isolates was also detected in the organic farms (14.9%). High resistance frequencies were observed for boscalid (67.7%), pyraclostrobin (67.3%), cyprodinil (65.9%), and thiophanate-methyl (61.4%) in conventional farms, while high levels of multiple fungicide resistance were also evident. Furthermore, B. cinerea isolates were genotyped using a set of seven microsatellite markers (simple sequence repeat [SSR] markers). Index of association analyses (Ia and rBarD) suggest asexual reproduction of the populations, even though the mating-type idiomorphs were equally distributed, indicating frequency-dependent selection. Fungicide resistance was correlated with farming systems across countries and crops, while SSRs were able to detect population structure associated with resistance to thiophanate-methyl, pyraclostrobin, boscalid, and cyprodinil. The expected heterozygosity in organic farms was significantly higher than in conventional, suggesting the absence of selective pressure that may change the allelic abundance in organic farms. However, genetic variance among strawberry and tomato populations was high, ranking host specificity higher than other selection forces studied.

Characterization of Phytophthora infestans Populations in Cyprus, the Southernmost Potato-Producing European Country.

Cyprus is the southernmost island country of Europe, located in the Mediterranean. Despite its limited area, potato production is considered an integral source of the national agricultural revenue. During 2010-2012, a late blight epidemic period for the country, the population structure of Phytophthora infestans was analyzed via a sample of 539 isolates collected from all of the main potato-cultivating regions of Cyprus. We determined mating type, mefenoxam sensitivity, and genetic polymorphism at 12 simple sequence repeat (SSRs) loci. Although both mating types were detected in the country, a gradual but dynamic shift toward A2 dominance was manifested over time. The pathogen population also demonstrated reduced sensitivity to the phenylamide fungicide, since 96.2% of the tested isolates had high (70.3%) and intermediate (25.9%) resistance to mefenoxam, which suggests that it should be replaced with other active ingredients in local disease management strategies. The genotypic analysis also revealed the predominance of the highly aggressive mefenoxam-insensitive EU_13_A2 lineage across the country, with a frequency of 79.2%. Other samples comprised an older lineage EU_2_A1 (19.5%), a very low proportion of EU_23_A1 (0.37%), and others that did not match any known lineage (0.92%). SSRs data supported triploid genomes among the dominant lineages, and patterns of their asexual population history were also apparent. A high subclonal variation of the 13_A2 population was detected, which suggested introduction events of this widespread genotype to Cyprus from major tuber-exporting countries. Present data indicate the severe impact of inoculum migration to the structure of the local population; thus, current phytosanitary procedures should be reconsidered and possibly attuned. This is the first comprehensive study to elucidate the diversity of P. infestans in Cyprus and could serve as a baseline for future monitoring of this highly adaptive plant pathogen, given that late blight management strategies should be constantly refined according to the traits of the dominant genotypes of P. infestans.