Diversity and pathogenicity of pestalotioid fungi species associated with blueberry plants in Portugal

• Autor(a) principal: Santos, João Diogo Fernandes
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/31931
• topic: Vaccinium corymbosum; Blueberry; Pestalotiopsis; Neopestalotiopsis; Taxonomy; Patogenicity

Blueberry (Vaccinium corymbosum) is a perennial shrub, native to North America whose popularity has increasing due to its health benefits. In Portugal, this culture represents an important part of the country's economy, being cultivated in several regions. However, the fast growth of production has been accompanied by the appearance of pathogens, mainly fungi. Considering that studies carried out on pathogenic blueberry fungi in Portugal are still quite scarce, this study aimed to identify species of the genera Pestalotiopsis and Neopestalotiopsis, which are known pathogens severely affecting blueberry plantations worldwide. Therefore, a collection of 51 isolates was obtained from symptomatic blueberry plants collected in different cultivation orchards in Portugal. In order to assess the genetic diversity of our collection, all isolates were subjected to MSP-PCR fingerprinting. According to the analysis of the genetic profiles, 16 representative isolates were chosen for a molecular identification based on the sequencing and analysis of the ITS region, which allowed to identify 2 different genera: Pestalotiopsis and Neopestalotiopsis. To better discriminate the isolates at species level, a multi-locus sequence analysis was performed using, in addition to the ITS region, the protein coding genes: translation elongation factor 1-alpha (tef1-α) and beta-tubulin 2 (tub2). A phylogenetic analysis of the ITS, tef1-α and tub2 regions revealed the presence of 4 known species, placed into distinct clades (Pestalotiopsis chamaeropis, P. biciliata, P. australis and Neopestalotiopsis rosae), and 3 putative new species. These were characterized in terms of morphology and ability to grow at different temperatures and the names N. baccae, N. scalabiensis and N. vaccinii proposed. Of all the identified species, N. vaccinii and N. rosae were the most abundant. The pathogenicity tests carried out revealed that all tested species were pathogenic to blueberry plants (cultivar Duke). Among the species tested, P. biciliata and N. rosae were the most aggressive ones. Plants inoculated with isolates from these species exhibited more extensive branch necrosis and, in some cases, death of the plant. To our knowledge, this represents the first study and the first report of species of Pestalotiopsis and Neopestalotiopsis in blueberries in Portugal. The diversity and distribution of these species, as well as their pathogenic potential, need to be further explored in the future.