Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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Item Phoma destructiva causing blight of tomato plants: a new fungal threat for tomato plantations in Brazil?(Tropical Plant Pathology, 2017-11-20) Colmán, Adans A.; Alves, Janaina L.; Silva, Meiriele da; Barreto, Robert W.Solanum lycopersicum is among the most important crops in Brazil. This crop is affected by a large range of fungal diseases that are recognized as major limitations for tomato production. Recently, plants grown in a greenhouse in Viçosa, Minas Gerais, Brazil, were found to bear severe blight symptoms. A pycnidial coelomycete was repeatedly found in association with necrotic tissues. The fungus had its morphology recognized as equivalent to that of Phoma and related genera. A phylogenetic analysis based on nrDNA (ITS) and partial β-tubulin (TUB) sequences led to the conclusion that the fungus involved was Phoma destructiva. Pathogenicity tests showed that, after 5 days, blight symptoms developed on leaves, flowers and stems of plants belonging to thirteen different tomato varieties tested. This fungal species is mostly known for causing post-harvest tomato rot, which is only regarded as a secondary disease in Brazil. This is in disagreement with the observations made in this work. Here, the disease symptoms caused by the fungus were very severe, fully justifying the scientific name of the pathogen. Under favorable environmental conditions, aggressive strains of P. destructiva, such as the one isolated in this study, may become significant threats to tomato plantations in Brazil.Item The Colletotrichum orbiculare species complex: Important pathogens of field crops and weeds(Fungal Diversity, 2013-06-27) Barreto, Robert W.; Guatimosim, Eduardo; Crous, Pedro W.; Liu, Fang; Cannon, Paul F.; Damm, UlrikeColletotrichum orbiculare causes anthracnose of Cucurbitaceae and is phylogenetically closely related to pathogens of several other herbaceous hosts belonging to the Asteraceae, Fabaceae and Malvaceae. Most of them are known for their hemibiotrophic infection strategy and as destructive pathogens either of field crops or weeds. In order to study the phylogenetic relationships of these fungi, a multilocus analysis (ITS, GAPDH, CHS-1, HIS3, ACT, TUB2, GS) of 42 strains of C. orbiculare and related species was conducted. The analysis resulted in nine clades that confirmed the four species previously known as belonging to this species complex, C. lindemuthianum, C. malvarum, C. orbiculare and C. trifolii, and recognised four new species from weeds, namely C. bidentis, C. sidae, C. spinosum and C. tebeestii. The name C. orbiculare itself is widely used in plant pathology and science, but is invalid according to current nomenclatural rules. Therefore we described a new species with the same epithet and a type specimen that agrees with our current understanding of this species, and is linked to a living culture. Following the recent epitypification of C. lindemuthianum, we chose appropriate specimens with associated strains to serve as epitypes of C. malvarum and C. trifolii, and selected an authentic specimen of C. trifolii as lectotype.Item A new species of the lenticel fungal genus Claviradulomyces (Ostropales) from the Brazilian Atlantic forest tree Xylopia sericea (Annonaceae)(IMA Fungus, 2012-11-15) Barreto, Robert W.; Johnston, Peter R.; Crous, Pedro W.; Evans, Harry C.Claviradulomyces xylopiae sp. nov. is introduced for a fungus occurring in association with abnormal (enlarged, spongy) lenticels of Xylopia sericea (Annonaceae), a common tree of the Atlantic forest and Cerrado ecosystems in Brazil. This is the second species described in the genus and, although it is morphologically distinct from the type species, C. dabeicola from West Africa, it possesses the same characteristics. Apothecial ascomata have periphysoids and paraphyses that are inflated apically (clavate), and ornamented with denticles (raduliform). Furthermore, similar to the type species, it also has long-cylindric or acerose, aseptate ascospores and conidia. An additional asexual morph was produced in culture and is described. Molecular studies of C. dabeicola and the new species confirmed a placement in Ostropales, although a relationship to Odontotremataceae was not supported. Both species were consistently in association with abnormal lenticular development on their woody hosts. It remains to be ascertained, however, if these are the causal agents of the bark disorders, or, simply, opportunistic colonisers. The finding of the second species in the genus Claviradulomyces on a plant from a distantly related family to that of the host of C. dabeicola (Erythroxylaceae) for the genus on a different continent suggests that fungi in this genus may be common on lenticels of other woody plants, and could even have a pantropical distribution. It is possible that fungi in the genus have remained unreported until now because lenticels have remained neglected as a habitat surveyed by mycologists.