RESUMEN
Pecan (Carya illinoinensis) is one important exotic forest crop cultivated in South America, specifically in Brazil, Uruguay, and Argentina. However, diseases such as anthracnose, favored by high humidity conditions and high summer temperatures, make its cultivation difficult, causing important loss to pecan farmers. This study used morphological and molecular approaches to identify the Colletotrichum species causing anthracnose in pecan plantations in Southern Brazil. The isolates obtained from pecan fruits with anthracnose symptoms were grouped through quantitative morphological characteristics into three distinct morphotypes. Molecular analysis of nuclear genes allowed the identification of six species of Colletotrichum causing anthracnose in pecan: C. nymphaeae, C. fioriniae, C. gloeosporioides, C. siamense, C. kahawae, and C. karsti. Three of these species are reported for the first time as causal agents of anthracnose in pecan. Therefore, these results provide an important basis for the adoption and/or development of anthracnose management strategies in pecan orchards cultivated in southern Brazil and neighboring countries.
Asunto(s)
Carya , Colletotrichum , Colletotrichum/genética , Brasil , Filogenia , Enfermedades de las PlantasRESUMEN
The Serendipitaceae family was erected in 2016 to accommodate the Sebacinales 'group B' clade, which contains peculiar species of cultivable root-associated fungi involved in symbiotic associations with a wide range of plant species. Here we report the isolation of a new Serendipita species which was obtained from protocorms of the terrestrial orchid Epidendrum fulgens cultivated in a greenhouse. This species is described based on phylogenetic analysis and on its microscopic and ultrastructural features in pure culture and in association with the host's protocorms. Its genome size was estimated using flow cytometry, and its capacity to promote the germination of E. fulgens seeds and to associate with roots of Arabidopsis thaliana was also investigated. Serendipita restingae sp. nov. is closely related to Serendipita sp. MAFF305841, isolated from Microtis rara (Orchidaceae), from which it differs by 14.2% in the ITS region and by 6.5% in the LSU region. It produces microsclerotia formed of non-monilioid hyphae, a feature that was not reported for the Sebacinales hitherto. Serendipita restingae promoted the germination of E. fulgens seeds, forming typical mycorrhizal pelotons within protocorm cells. It was also able to colonize the roots of Arabidopsis thaliana under in vitro conditions. Arabidopsis plants grown in association with S. restingae increased their biomass more than fourfold. Serendipita restingae is the first Serendipitaceae species described for the Americas.
Asunto(s)
Basidiomycota , Micorrizas , Orchidaceae , Basidiomycota/genética , Especificidad del Huésped , Filogenia , SimbiosisRESUMEN
The asymbiotic technique of orchid seeds germination is an important method of mass production of seedlings. Studies on the best culture conditions for each species are important to obtain seedlings in less time and at lower costs. Current analysis evaluates different consistencies of culture medium, saline formulations and culture conditions on the germination rate and further development of protocorms of Epidendrum fulgens. After 45 days in culture the protocorms were classified into three categories of development. The liquid saline formulation of Murashige and Skoog (1962) (MS) provided the highest germination rate (83.5%), and the Knudson formulation (1946) the lowest (10.9%). The different consistencies or conditions or culture conditions did not affect the germination rate percentage, except the Knudson medium, which resulted in the highest rate in response to the gelled consistency. Protocorms cultured in liquid MS medium with or without agitation showed the fastest development.
A técnica da germinação assimbiótica de sementes de orquídeas é um importante método de produção massal de mudas. Estudos que buscam condições de cultivo ideais para cada espécie são altamente desejados para obterem-se mudas em menor tempo e com menor custo. Este estudo objetivou testar diferentes consistências de meio de cultura, formulações salinas e condições de cultivo na porcentagem de germinação e velocidade de desenvolvimento de protocormos de Epidendrum fulgens. Após 45 dias de cultivo, os protocormos foram classificados em três categorias de desenvolvimento. A formulação salina de Murashige e Skoog (1962) (MS) líquida, sem agitação orbital, proporcionou maior taxa de germinação (83,5%), e a formulação de Knudson (1946) o menor percentual (10,9%). As diferentes consistências ou condições de cultivo não influenciaram na porcentagem de germinação, exceto para o meio Knudson, onde na consistência geleificada o percentual foi maior. Os protocormos cultivados em meio MS líquido, com ou sem agitação, apresentaram maior velocidade de desenvolvimento.