Alguns fungos do Brasil (Phycomycetos)

Viégas, A. P.; Teixeira, A.

doi:10.1590/s0006-87051943000800003

Cited by 24 publications

(24 citation statements)

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“…2006), which is hitherto known only from Brazil. It differs from P. tibouchinae in that the latter species has narrowly subcylindrical conidia that are larger, 40-120 × 2-3 μm (Viégas 1945), than those of P. tibouchinigena. The subhyaline conidia of P. tibouchinigena are not typical of Pseudocercospora s. str ., but for the present, we choose to name it in Pseudocercospora until the clade in which it resides has been more fully resolved (Fig.…”

Section: Resultsmentioning

confidence: 85%

Phylogenetic lineages in Pseudocercospora

Crous¹,

Braun²,

Hunter³

et al. 2013

Studies in Mycology

194

253

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Pseudocercospora is a large cosmopolitan genus of plant pathogenic fungi that are commonly associated with leaf and fruit spots as well as blights on a wide range of plant hosts. They occur in arid as well as wet environments and in a wide range of climates including cool temperate, sub-tropical and tropical regions. Pseudocercospora is now treated as a genus in its own right, although formerly recognised as either an anamorphic state of Mycosphaerella or having mycosphaerella-like teleomorphs. The aim of this study was to sequence the partial 28S nuclear ribosomal RNA gene of a selected set of isolates to resolve phylogenetic generic limits within the Pseudocercospora complex. From these data, 14 clades are recognised, six of which cluster in Mycosphaerellaceae. Pseudocercospora s. str. represents a distinct clade, sister to Passalora eucalypti, and a clade representing the genera Scolecostigmina, Trochophora and Pallidocercospora gen. nov., taxa formerly accommodated in the Mycosphaerella heimii complex and characterised by smooth, pale brown conidia, as well as the formation of red crystals in agar media. Other clades in Mycosphaerellaceae include Sonderhenia, Microcyclosporella, and Paracercospora. Pseudocercosporella resides in a large clade along with Phloeospora, Miuraea, Cercospora and Septoria. Additional clades represent Dissoconiaceae, Teratosphaeriaceae, Cladosporiaceae, and the genera Xenostigmina, Strelitziana, Cyphellophora and Thedgonia. The genus Phaeomycocentrospora is introduced to accommodate Mycocentrospora cantuariensis, primarily distinguished from Pseudocercospora based on its hyaline hyphae, broad conidiogenous loci and hila. Host specificity was considered for 146 species of Pseudocercospora occurring on 115 host genera from 33 countries. Partial nucleotide sequence data for three gene loci, ITS, EF-1α, and ACT suggest that the majority of these species are host specific. Species identified on the basis of host, symptomatology and general morphology, within the same geographic region, frequently differed phylogenetically, indicating that the application of European and American names to Asian taxa, and vice versa, was often not warranted.Taxonomic novelties:New genera - Pallidocercospora Crous, Phaeomycocentrospora Crous, H.D. Shin & U. Braun; New species - Cercospora eucommiae Crous, U. Braun & H.D. Shin, Microcyclospora quercina Crous & Verkley, Pseudocercospora ampelopsis Crous, U. Braun & H.D. Shin, Pseudocercospora cercidicola Crous, U. Braun & C. Nakash., Pseudocercospora crispans G.C. Hunter & Crous, Pseudocercospora crocea Crous, U. Braun, G.C. Hunter & H.D. Shin, Pseudocercospora haiweiensis Crous & X. Zhou, Pseudocercospora humulicola Crous, U. Braun & H.D. Shin, Pseudocercospora marginalis G.C. Hunter, Crous, U. Braun & H.D. Shin, Pseudocercospora ocimi-basilici Crous, M.E. Palm & U. Braun, Pseudocercospora plectranthi G.C. Hunter, Crous, U. Braun & H.D. Shin, Pseudocercospora proteae Crous, Pseudocercospora pseudostigmina-platani Crous, U. Braun & H.D. Shin, Pseudocercospora ...

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Section: Resultsmentioning

confidence: 85%

Phylogenetic lineages in Pseudocercospora

Crous¹,

Braun²,

Hunter³

et al. 2013

Studies in Mycology

194

253

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“…3, 4) Vi~gas). In his description of R. parahybana, Vi~gas (1945) supposed that the host belonged to the genus Caesalpinia. This opinion was also held by Hennen and Cummins (1990) when they compared R. corbuloides with R. pileolarioides.…”

Section: Berndt (Herb C-5)mentioning

confidence: 99%

Ravenelia cenostigmatis, a new rust fungus from Brazil

Berndt¹,

Freire²

2000

Mycoscience

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Ravenelia cenostigmatis is described as a new species of plant rust (Uredinales) on Cenostigma gardnerianum (Caesalpiniaceae) from Brazilian Cerrado. Teliospore heads of R. cenostigmatis exhibit an unusually complex structure with four different kinds of cells: teliospore cells, sterile apical cells (intercalary between pedicel hyphae and teliospores), sterile hygroscopic cysts, and morphologically distinct border cells. The last are flattened, elaborately ornamented and probably sterile cells that are wedged between the teliospores and the cysts. Ravenelia cenostigmatis probably belongs to a natural assemblage of ravenelias that occur on caesalpiniaceous hosts and exhibit similar morphological traits. Key WordsCaesalpiniaceae; Kemkarnpella; systematics; teliospore morphology.The genus Ravenelia comprises about 190 species that are distributed in the subtropics and tropics around the world and infect almost exclusively members of Leguminosae. The telial morphology of Ravenelia species is unique: Complex teliospore heads are subtended by hygroscopic sterile cysts and consist of several teliospores and sterile apical cells (between teliospores and stalk hyphae). Similar teliospore heads occur only in the genus Spumula that cannot be sharply delimited from Ravenelia (Berndt, 1996) and in Kernkampella.A rust specimen recently collected on Cenostigrna gardnerianum Tul. (Caesalpiniaceae) in the Cerrado dry forest of NE Brazil was assigned to Ravenelia because of its typical teliospore heads and the leguminous host.The specimen was different from the only other Ravenelia on Cenostigma, R. spiralis Hennen & Cummins, and other members of the genus. It is therefore described as new. Ravenelia cenostigmatisFigs. 1-6 (etymology: named after the host genus, Cenostigma) Uredinia non observata. Urediniosporae solitariae, in teliis sparsae, ochraceae ad clare brunneae, late ellipsoideae, obovoideae vel subglobosae, 24-31 • 20-24/~m (Iongitudine media 27pm, latitudine media 22.2/~m), membrana indistincte bilaminata, ca. 2-2.5pm crassa, ad apicem leniter incrassata vel crassa usque ad 5-7(-9) /~m, lamina exteriore tenuissima, subhyalina, spiraliter denseque striata (spatium inter strias ca. 2/zm), striis delicate incisis, poris germinationis (2-)3(-4), prope hilum sitis. Telia abaxialia, dense sparsa, ca. 0.2-0.3 Part 179 of the series "Studies in Heterobasidiomycetous Fungi" of the Botanical Institute, University of T6bingen ~ Corresponding author. E-mail: reinhard.berndt(~uni-tuebingen.de mm diametro, atrobrunnea, complanate globuliformes, paraphysibus periphericis copiosis, incurvatis, ca. 55-130• pariete aurantiaco, dorsaliter et ad apicem valde incrassato. Capitulae teliosporarum castaneae, globosae, subglobosae vel late ellipsoideae, 60-100 [tm diametro, ex 3-6 cellulis in omni directione compositae, teliosporae unicellulatae, sporae centrales 18-27x 15-20/~m (Iongitudine media 21.3/~m, latitudine media 18/~m), membrana bilaminata, exteriore tenui, subhyalina, verrucis inconspicuis, latis et applanatis dense sitis, interi...

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“…Several diseases threaten corn production in Brazil, particularly those related to seed germination, seedling emergence, root rots, stem rots, ear rots, rusts, smuts, along with leaf blights and spots (Reis et al, 2004). Of the latter, the principal ones reported in Viégas andKrug in 1934 (Viégas, 1945), the latter has rarely been recorded since, and did not reach epidemic proportions at the time. However, in the southwestern regions of Goiás state, a devastating reemergence of GLS occurred, destroying the entire healthy leaf area of the second corn crop in 2000 and, in a short period of time, killing the plants altogether.…”

Section: Introductionmentioning

confidence: 99%

Critical-point yield model to estimate yield damage caused by Cercospora zea-maydis in corn

2007

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A model to estimate damage caused by gray leaf spot of corn (Cercospora zea-maydis) was developed from experimental field data gathered during the summer seasons of 2000/01 and during the second crop season [Januaryseedtime] of 2001, in the southwest of Goiás state. Three corn hybrids were grown over two seasons and on two sites, resulting in 12 experimental plots. A disease intensity gradient (lesions per leaf) was generated through application, three times over the season, of five different doses of the fungicide propiconazol. From tasseling onward, disease intensity on the ear leaf (El), and El -1, El -2, El + 1, and El + 2, was evaluated weekly. A manual harvest at the physiological ripening stage was followed by grain drying and cleaning. Finally, grain yield in kg.ha -1 was estimated. Regression analysis, performed between grain yield and all combinations of the number of lesions on each leaf type, generated thirty linear equations representing the damage function. To estimate losses caused by different disease intensities at different corn growth stages, these models should first be validated. Damage coefficients may be used in determining the economic damage threshold.Additional keywords: gray leaf spot, Zea mays, losses. RESUMO Modelo de ponto crítico para estimar os danos causados por Cercospora zea-maydis em milhoDesenvolveu-se um modelo para estimar os danos causados pela cercosporiose (Cercospora zea-maydis) na cultura do milho, com base em dados experimentais de campo, coletados nas safras de verão nos anos 2000/01 e na safrinha de 2001, no sudoeste goiano. Três cultivares de milho híbrido foram semeados em dois locais perfazendo um total de 12 experimentos. O gradiente da intensidade da doença, avaliada em função do número de lesões por folha, foi gerado pela aplicação de cinco doses em três épocas. A intensidade da doença foi avaliada, semanalmente, em cinco folhas, a partir do embonecamento: folha da espiga (Fe), Fe -1, Fe -2, Fe +1 e Fe +2. A colheita foi realizada na maturação fisiológica e o rendimento de grãos expresso em kg.ha -1 . As análises de regressão entre o rendimento de grãos e o número de lesões nas cinco folhas foram realizadas para todas as combinações obtidas e geraram 30 equações lineares da função de dano. Para estimativas de danos causados por diferente intensidade da doença, em diferentes estádios de desenvolvimento fenológico, esses modelos devem, antes de tudo, serem validados. Os valores dos coeficientes de dano podem potencialmente serem utilizados no cálculo do limiar de dano econômico.Palavras-chave adicionais: mancha foliar cinzenta, Zea mays, danos.

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Alguns fungos do Brasil (Phycomycetos)

Cited by 24 publications

References 1 publication

Phylogenetic lineages in Pseudocercospora

Phylogenetic lineages in Pseudocercospora

Ravenelia cenostigmatis, a new rust fungus from Brazil

Critical-point yield model to estimate yield damage caused by Cercospora zea-maydis in corn

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