Fitopatologia - Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11741
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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.Item A new species of Calonectria causing leaf blight and cutting rot of three forest tree species in Brazil(Tropical Plant Pathology, 2013-08-13) Alfenas, Rafael F.; Pereira, Olinto L.; Jorge, Vanessa L.; Crous, Pedro W.; Alfenas, Acelino C.Several species of Calonectria cause diseases on a wide range of forest tree species that are propagated either via seedlings or rooted cuttings. In nurseries these fungi cause damping-off, cutting and root rots, stem lesions, and leaf blights. Recently a Calonectria sp. was isolated from rooted cuttings of Anadenanthera peregrina (Fabaceae), Piptadenia gonoacantha (Fabaceae), and Azadirachta indica (Meliaceae) exhibiting leaf blight and cutting rot in a forest nursery at the Universidade Federal de Viçosa, Brazil. Morphological comparisons and DNA sequences of three loci containing partial gene sequences of β-tubulin (TUB2), calmodulin (CAL), and elongation factor (TEF-1α) indicated that these isolates represent an unnamed species of Calonectria, described here as C. hodgesii sp. nov. Sprayinoculated plants of all three hosts with a suspension at 1x104 conidia mL-1 induced leaf lesions, cutting rot, and intense defoliation as observed under natural conditions. Calonectria hodgesii was re-isolated from infected tissue, which fulfilled Koch's postulates and confirmed its status as a pathogen with a wide host range.