Conidia sporulation of Pyricularia oryzae in segments of wheat plants under six different temperatures / Esporulação de conídios de Pyricularia oryzae em segmentos de plantas de trigo sob seis diferentes temperaturas

ABSTRACT: Wheat blast is known for developing itself more intensely under relatively high temperature conditions but many aspects related to its epidemiology remain unknown. The objective of this research was to evaluate the sporulative capacity of Pyricularia oryzae Triticum (Pot), the causal agent of wheat blast, in tissues of wheat plants under different temperatures degrees. Wheat plants of the cultivar Anahuac 75, susceptible to blast, were inoculated in the stage of flowering with conidial suspensions (105 conidia/mL) of the Pot isolates Py 12.1.209 and Py 12.1.132. Seven days after the inoculation, plants were cut in the following segments: leaves, stems and rachis (with blast severity ranging from 40 to 60%). Groups of each one of the three plant segments with the lesions were disposed in Petri-dish moist chambers, that were submitted to six different temperature treatments (18, 21, 24, 27, 30 and 33 °C). The most appropriate model that related the conidia production with temperature was identified in the evaluations conducted with stems. The established equations allowed identifying that the highest production of conidia of Pot occurs between 24 and 27 °C.

RESUMO: Sabe-se que a brusone do trigo ocorre preferencialmente em condições de temperaturas relativamente altas, porém muitos aspectos sobre a epidemiologia desta doença ainda permanecem desconhecidos. O objetivo deste trabalho foi avaliar a capacidade esporulativa de Pyricularia oryzae Triticum (Pot) em tecidos de plantas de trigo sob diferentes temperaturas. Plantas de trigo do cultivar Anahuac 75, suscetível à brusone, foram inoculadas no estádio do florescimento com suspensões de conídios dos isolados Py 12.1.209 e Py 12.1.132 de Pot (105 conídios/mL). Sete dias após a inoculação, as plantas foram cortadas e separadas em três tipos de segmentos: colmos, folhas e ráquis (com severidade de brusone variando de 40 a 60%). Um grupo de cada desses três tipos de segmentos de planta contendo lesões foi disposto em câmara úmida. O material foi acondicionado em seis níveis de temperatura: 18, 21, 24, 27, 30 e 33 °C. O modelo mais apropriado que relacionou a produção de conídios com temperatura foi identificado nas avaliações feitas nas amostras de colmo. As equações estabelecidas permitiram identificar que a maior produção de conídios de Pot ocorreu entre as temperaturas de 24 e 27 °C.

Evaluation of Antifungal Activities of Five Plant Extracts against Pseudoperenospora cubensis (Downy Mildew) in Muskmelon (Cucumis melo L.)

Laboratory study was conducted to evaluate the effect of leaf extracts of five indigenous plant on conidia germination, growth and sporulation of Pseudoperenospora cubensis causing downy mildew disease of muskmelon. Extracts of five plant; mexican sunflower (Tithonia diversifolia), bush banana (Uvaria chamae), salt and oil tree (Cleistopholis patens), goat weed (Ageratum conyzoides) and African eggplant (Solanum macrocarpon) at Four concentrations (15, 30, 45 and 60%) were tested against the growth, conidial germination and sporulation of Pseudoperenospora cubensis in vitro. Results show that all the plant extracts significantly inhibited conidia germination and radial growth compared to the control. The extracts had no significant (p≤0.05) effect on sporulation. The rate of inhibition of growth and conidia germination was concentration dependent being highest at 60% for the extracts. The extracts of Solanum macrocarpon was the most effective followed by Ageratum conyzoides, Cleistopholis patens and Uvaria chamea whileTithonia diversifolia caused the least inhibition of growth and conidia germination. At 15, 30, 45 and 60% concentrations growth of Pseudoperenospora cubensis on PDA modified with Solanum macrocqrponwere 3.79, 3.65, 3.33 and 2.87; and 4.25, 4.12, 3.92 and 3.89 for PDA modified with Tithonia diversifolia. Similarly, conidia germination percentages recorded at same concentration of extracts S. macrocarpon were 87, 85, 70 and 62% while that of T. diversifolia were 91, 87, 84 and 72%. The study shows that the plant extracts has the potential for inhibition of the pathogen.

European apple canker: morphophysiological variability and pathogenicity in isolates of Neonectria ditissima in southern Brazil / Cancro europeu da macieira: variabilidade morfofisiológicas e patogenicidade de isolados de Neonectria ditissima no sul do Brasil

ABSTRACT: European apple canker (EC) is caused by Neonectria ditissima, a pathogen officially registered as a quarantine pest in 2012. Thirty-five isolates of N. ditissima of different geographical regions of southern Brazil from apple branches showing symptoms of EC were identified by the specific pair primers Ch1 and Ch2 and analyzed concerning the virulence on Gala apple cultivar and morphophysiological characteristics. The disease symptoms were characterized and the isolates compared based on average mycelium growth (AMG), mycelium growth index (MGI), colony color, conidia type, dimensions and growth on potato dextrose agar (PDA), malt agar (AM), and synthetic SNAY (SN) culture media. Nineteen isolates showed the greatest AMG on PDA, forming three growth groups of 35.56 (GI), 52.71 (GII), and 62.67mm (GIII). Seven isolates showed MGI greater than 4.0mm diameter on PDA compared with that on AM and SN. The highest conidia production was on SN, and the predominant colony color in all media was white to beige with central pigmentation of brown and borders colored in shades of beige. There were significant differences among the average dimensions of micro- and macroconidia on PDA, AM, and SN. The pathogenicity was confirmed for all isolates despite of different morphophysiological characteristics. There was no correlation among isolates morphophysiological variability, virulence, and geographical origin.

RESUMO: O cancro europeu (CE) da macieira é causado pelo fungo Neonectria ditissima e foi oficialmente registrado como praga quarentenária em 2012. Foram avaliados 35 isolados de N. ditissima provenientes de ramos de macieira com sintomas típicos de CE de diferentes regiões do sul do Brasil. Os isolados foram identificados pelos primers específicos Ch1 e Ch2 e analisados quanto as características morfofisiológicas e virulência na cultivar de macieira Gala. Os sintomas foram caracterizados e os isolados comparados com base no crescimento micelial médio (CMM), índice de crescimento micelial (ICM), coloração das colônias e tipos, dimensões e produção de conídios em meios de cultura batata-dextrose-ágar (BDA), malte-ágar (MA) e meio sintético SNAY (SS). Dezenove isolados tiveram os maiores CMM sobre BDA, formando três grupos de crescimento de 35.56 (GI), 52.71 (GII) e 62.67mm (GIII). Sete isolados tiveram ICM maior de 4mm de diâmetro sobre BDA quando comparados com os meios MA e SS. A maior produção de conídios ocorreu sobre o meio SS e a coloração predominante foi de branco-à-bege com pigmentação central marrom e bordas de colônia em tons de bege. Foram observadas diferenças significativas nas dimensões médias dos micro- e macroconídios sobre os meios de culturas BDA, MA e SS. Todos os isolados foram patogênicos na cultivar de macieira gala, independentemente das diferenças morfofisiológicas. Não foram observadas correlações entre a variabilidade morfofisiológicas, virulência e origem geográfica dos isolados.

Nuevos registros de hongos anamórficos para Guatemala / New records of anamorph fungi from Guatemala

Los hongos anamorfos constituyen un grupo muy diverso microscópicos cuya forma de reproducción es asexual a través de conidios. Actúan como agentes de degradación de la materia vegetal en el suelo, lo cual es un proceso clave en el reciclaje de nutrientes. Debido a la importancia y al vacío de información que existe sobre estos hongos en Guatemala, en este trabajo se identificaron 12 especies, por medio de características microscópicas; luego de la extracción de las estructuras fúngicas desarrolladas en hojas, ramas y semillas recolectadas en una parcela de la Reserva Ecológica Cayalá de la Ciudad de Guatemala. El material de referencia está depositado en la colección de hongos anamorfos de la Micoteca de Macrohongos de Guatemala "Lic. Rubén Mayorga Peralta" (MICG)

Anamorphic fungi are a diverse group of microscopic fungi that reproduce asexually through conidia. They degrade plant debris on the soil, which is a key process in nutrients recycling. Because of its importance and the lack of information regarding to these fungi in Guatemala, In this article, 12 species were identified through microscopic characteristics, after extraction of fungal structures developed in leaves, twigs and seeds collected at the Cayalá Ecological Reserve in Guatemala City. Reference materials are placed at the anamorphic fungi collection at Micoteca de Macro hongos de Guatemala, "Dr. Ruben Mayorga Peralta" (MICG).

Conidial germination in Scedosporium apiospermum, S. aurantiacum, S. minutisporum and Lomentospora prolificans: influence of growth conditions and antifungal susceptibility profiles

In the present study, we have investigated some growth conditions capable of inducing the conidial germination in Scedosporium apiospermum, S. aurantiacum, S. minutisporum and Lomentospora prolificans. Germination in Sabouraud medium (pH 7.0, 37ºC, 5% CO2) showed to be a typically time-dependent event, reaching ~75% in S. minutisporum and > 90% in S. apiospermum, S. aurantiacum and L. prolificans after 4 h. Similar germination rate was observed when conidia were incubated under different media and pHs. Contrarily, temperature and CO2 tension modulated the germination. The isotropic conidial growth (swelling) and germ tube-like projection were evidenced by microscopy and cytometry. Morphometric parameters augmented in a time-dependent fashion, evidencing changes in size and granularity of fungal cells compared with dormant 0 h conidia. In parallel, a clear increase in the mitochondrial activity was measured during the transformation of conidia-into-germinated conidia. Susceptibility profiles to itraconazole, fluconazole, voriconazole, amphotericin B and caspofungin varied regarding each morphotype and each fungal species. Overall, the minimal inhibitory concentrations for hyphae were higher than conidia and germinated conidia, except for caspofungin. Collectively, our study add new data about the conidia-into-hyphae transformation in Scedosporium and Lomentospora species, which is a relevant biological process of these molds directly connected to their antifungal resistance and pathogenicity mechanisms.

Diversity of leaf endophytic fungi in mangrove plants of Northeast Brazil

With the aim of increasing the knowledge about endophytic fungi, a group of microorganisms with high biotechnological potential and a valuable source of useful metabolites, a survey in leaves of mangrove plants (Avicennia schaueriana, Laguncularia racemosa, and Rhizophora mangle) was performed at the Itamaracá Island, PE, Brazil. Leaves were collected, during two seasons, dry and rainy, superficially sterilized and fragments maintained in Petri dishes with Potato dextrose agar (PDA) at 28º ± 2º C until isolation of the fungi. Fourty taxa were isolated: 25 species representing 19 genera and 15 morphotypes determined as Mycelia sterilia. Leaves of L. racemosa hosted the highest number of colony forming units (CFU) and taxa. Guignardia sp. and Colletotrichum gloeosporioides were the most frequently isolated, while Glomerella cingulata was the only species found in association with the three host plants. The proportional importance of each fungus differed among hosts. The similarity of fungi species between the two seasons reached only 4.2%, and that between the hosts was also low, with the maximum (A. schaueriana x L. racemosa) reaching 24.2%. Sphaerosporium, as well as Chloridium virescens var. virescens, Microsphaeropsis arundinis, Penicillium pinophilum, Periconia cambrensis, Phoma herbarum, P. diachenii, P. obscurans, Sordaria prolifica and Torula elisii are reported for the first time as endophytic in tropical regions.

Ultrastructural study of the mycelial phase of clinical isolates of Sporothrix schenckii obtained from feline, canine and human cases of sporotrichosis

Using transmission electron microscopy, we studied the presence of melanin and cell wall thickness of clinical isolates of Sporothrix schenckii obtained from cats, dogs and humans as compared to reference strains. We detected differences regarding presence of the melanin among the clinical isolates of S. schenckii and a correlation between presence of melanin and cell wall thickness.

Enhancing Effect of Shimizuomyces paradoxus on Seed Germination and Seedling Growth of Canola, Plant Growth of Cucumber, and Harvest of Tomato

Shimizuomyces paradoxus showed no inhibitory effect against plant pathogen fungi, such as Fusarium oxysporum f. sp. lycopersici and Alternaria solani. The S. paradoxus culture filtrate showed higher seed germination and seedling growth rates in canola than distilled water and potato-dextrose broth. A conidial suspension of 1.0x104/mL resulted in the highest growth stimulating effects on total plant length, and fresh and dry weight of shoots and roots in cucumber, when compared to the highest suspension concentration. Total plant length and shoot weight increased with the foliar spray treatment, and root length and root weight increased by simultaneous treatments of soil drenching and foliar spray in cucumber. Lower concentrations of the S. paradoxus conidial suspension increased the harvest of tomato fruit.

Effect of moisture content and inoculum on the growth and conidia production by Beauveria bassiana on wheat bran

The aim of the present work was to study the effect of moisture content and inoculum on the growth and conidia production by Beauveria bassiana on wheat bran (WB).The highest growth rate of B. bassiana 885.2 on WB media was obtained at a w=1.0, with no detected growth at a w < 0.97. Solid-state fermentation (SSF) using WB (66 percent moisture; a w=1.0) achieved a maximal yield of 1.18x10 10 conidia per gram of dry substrate (gds). This yield decreased one order of magnitude with higher moisture contents or the addition of sugarcane bagasse (SCB) as a texturiser. In SSF using WB (66 percent humidity),the time to obtain a yield of 1x10(10) conidia/gds, referred to as t10, could be predicted using a model considering common inoculum levels and maximal yields. For instance, t10 was 285 h with an inoculum of 1x10(6) conidia/gds; however, t10 was reduced to 232 h and 148 for inocula of 7x10(6) and 5x10(7) conidia/gds, respectively. The estimation of t10 values allowed both comparison between the cultures and prediction of harvesting times in production processes. Values for hydrophobicity were within 90 and 92 percent, whereas viability averages were around 70 percent for all the cultures

Successful Development of Cordyceps bassiana Stromata from Beauveria bassiana

A specimen of Beauveria bassiana was collected from Yang-yang of Gangwon province, Korea in October 2006. Conidial isolates were prepared from the specimen by the dilution method and inoculated in brown rice medium for fruiting body production. After nearly two months incubation for perithecial stromata developed from single isolates as well as from their combinations. They were determined as Cordyceps bassiana by observing the stromatal characters and their conidial structures. This is the first report of the development of C. bassiana from B. bassiana cultures.

Compatibilidade de isolados de Beauveria bassiana (Ascomycetes: Clavicipitaceae) com carrapaticidas químicos utilizados no controle do carrapato dos bovinos / Compatibility of Beauveria bassiana (Ascomycetes: Clavicipitaceae) with chemicals acaricides used in the control of cattle tick

O presente trabalho teve como escopo avaliar a compatibilidade dos isolados IBCB66 e IBCB21 de Beauveria bassiana com os carrapaticidas a base de Flumetrina + Coumafós, Deltametrina, Diclorvós + Cipermetrina, Diclorvós + Clorpirifós, Cipermetrina High Cis, Diclorvós + Cipermetrina High Cis, Cipermetrina e Amitraz utilizados no controle do carrapato Rhipicephalus (Boophilus) microplus em nosso país. O efeito dos produtos comerciais sobre os isolados foi verificado por meio da observação do crescimento vegetativo, produção de conídios e viabilidade das estirpes do fungo B. bassiana. Com referência ao isolado IBCB66, os produtos Deltametrina, Cipermetrina High Cis e Amitraz foram classificados como compatíveis, não interferindo no desenvolvimento do entomopatógeno. O produto Cipermetrina foi classificado como tóxico e os produtos Flumetrina + Coumafós, Diclorvós + Cipermetrina, Diclorvós + Clorpirifós e Diclorvós + Cipermetrina High Cis, muito tóxicos. Em relação ao isolado IBCB21, os produtos Flumetrina + Coumafós, Diclorvós + Cipermetrina, Diclorvós + Clorpirifós, Cipermetrina High Cis, Diclorvós + Cipermetrina High Cis e Cipermetrina foram classificados como muito tóxicos e o produto Amitraz como tóxico. Entre os carrapaticidas avaliados, o produto Deltametrina foi o único que não produziu efeito tóxico sobre o entomopatógeno.

The purpose of the present study was to assess compatibility between IBCB66 and IBCB21 isolates of Beauveria bassiana and acaricides: Flumethrin + Coumaphos, Deltamethrin, Dichlorvos + Cypermethrin, Dichlorvos + Chlorpyrifos, Cypermethrin High Cis, Dichlorvos + Cypermethrin High Cis, Cypermethrin and Amitraz, utilized on the control of Rhipicephalus (Boophilus) microplus in our country. The effect of commercial products on the isolates was assayed according to observation of vegetative growth, conidia production, and viability of strains of B. bassiana fungus. With concerning about IBCB66 isolate, products Deltamethrin, Cypermethrin High Cis and Amitraz were compatible, not affecting the entomopathogen development. Product Cypermethrin was toxic, and products Flumethrin + Coumaphos, Dichlorvos + Cypermethrin, Dichlorvos+ Chlorpyrifos and Dichlorvos + Cypermethrin High Cis were very toxic. In regard to IBCB21 isolate, products Flumethrin + Coumaphos, Dichlorvos + Cypermethrin, Dichlorvos + Chlorpyrifos, Cypermethrin High Cis, Dichlorvos + Cypermethrin High Cis and Cypermethrin were very toxic and product Amitraz was toxic. From the acaricides evaluated, product Deltamethrin was the single agent that did not produce toxic effect on the entomopathogen.

Compatibilidade de isolados de Beauveria bassiana (Ascomycetes: Clavicipitaceae) com carrapaticidas químicos utilizados no controle do carrapato dos bovinos

The purpose of the present study was to assess compatibility between IBCB66 and IBCB21 isolates of Beauveria bassiana and acaricides: Flumethrin + Coumaphos, Deltamethrin, Dichlorvos + Cypermethrin, Dichlorvos + Chlorpyrifos, Cypermethrin High Cis, Dichlorvos + Cypermethrin High Cis, Cypermethrin and Amitraz, utilized on the control of Rhipicephalus (Boophilus) microplus in our country. The effect of commercial products on the isolates was assayed according to observation of vegetative growth, conidia production, and viability of strains of B. bassiana fungus. With concerning about IBCB66 isolate, products Deltamethrin, Cypermethrin High Cis and Amitraz were compatible, not affecting the entomopathogen development. Product Cypermethrin was toxic, and products Flumethrin + Coumaphos, Dichlorvos + Cypermethrin, Dichlorvos+ Chlorpyrifos and Dichlorvos + Cypermethrin High Cis were very toxic. In regard to IBCB21 isolate, products Flumethrin + Coumaphos, Dichlorvos + Cypermethrin, Dichlorvos + Chlorpyrifos, Cypermethrin High Cis, Dichlorvos + Cypermethrin High Cis and Cypermethrin were very toxic and product Amitraz was toxic. From the acaricides evaluated, product Deltamethrin was the single agent that did not produce toxic effect on the entomopathogen.

O presente trabalho teve como escopo avaliar a compatibilidade dos isolados IBCB66 e IBCB21 de Beauveria bassiana com os carrapaticidas a base de Flumetrina + Coumafós, Deltametrina, Diclorvós + Cipermetrina, Diclorvós + Clorpirifós, Cipermetrina High Cis, Diclorvós + Cipermetrina High Cis, Cipermetrina e Amitraz utilizados no controle do carrapato Rhipicephalus (Boophilus) microplus em nosso país. O efeito dos produtos comerciais sobre os isolados foi verificado por meio da observação do crescimento vegetativo, produção de conídios e viabilidade das estirpes do fungo B. bassiana. Com referência ao isolado IBCB66, os produtos Deltametrina, Cipermetrina High Cis e Amitraz foram classificados como compatíveis, não interferindo no desenvolvimento do entomopatógeno. O produto Cipermetrina foi classificado como tóxico e os produtos Flumetrina + Coumafós, Diclorvós + Cipermetrina, Diclorvós + Clorpirifós e Diclorvós + Cipermetrina High Cis, muito tóxicos. Em relação ao isolado IBCB21, os produtos Flumetrina + Coumafós, Diclorvós + Cipermetrina, Diclorvós + Clorpirifós, Cipermetrina High Cis, Diclorvós + Cipermetrina High Cis e Cipermetrina foram classificados como muito tóxicos e o produto Amitraz como tóxico. Entre os carrapaticidas avaliados, o produto Deltametrina foi o único que não produziu efeito tóxico sobre o entomopatógeno.

Stable Formation of Fruiting Body in Cordyceps bassiana

In order to breed a Cordyceps bassiana isolate that stably forms fruiting body in artificial cultivation, isolates derived from subculturing and single spores were tested through mating. From C. bassiana EFCC 783, three subcultured isolates EFCC 2830, EFCC 2831 and EFCC 2832 were obtained and fourteen single conidial isolates were obtained from these three subcultured isolates. Two different morphological types were found in the fourteen single conidial isolates. One type was able to form synnemata and another type was not able to form synnemata. Since switch of morphological type was not observed despite their continuous subculturing, cross was performed between the two types and the formation of fruiting body was examined. Ascospores were obtained from a selected fruiting body formed by hybrid of the cross. Self-cross and combinational cross of the ascospore-derived isolates generated hybrids that stably produce high quality fruiting body in artificial media.

Effects of Plant Extracts on Conidial Germination, Mycelial Growth and Sporulation of Fungi Isolated From Poultry Feed

Effect of ethanolic extracts of Lawsonia inermis, Azadirachta indica, Vinca rosea, Tagetes patula, Ocimum sanctum, Colocasia antiquorum, Adhatoda vasica, Moringa oleifera, Datura metel and Curcuma longa leaf on conidial germination, mycelial growth and sporulation of Aspergillus flavus, A. niger and A. fumigatus were examined. The conidial germination of A. flavus and A. fumigatus were most inhibited by the extract of L. inermis, while that of A. niger was inhibited by A. indica. Other tested plant extracts have a good effect on conidial germination on the selected fungi. The highest mycelial growth of A. flavus (37 mm) was found in V. rosea, but in case of A. niger and A. fumigatus it (38 and 39 mm) was found in D. metel. The lowest (4, 9 and 6 mm) respectively mycelial growth of these fungi found in L. inermis. The highest sporulation (75 x 10(4)/ml) of A. flavus was counted in V. rosea, but in case of A. niger and A. fumigatus those (45 x 10(4) and 55 x 10(4)/ml) were in D. metel and the lowest (5 x 10(4), 12 x 10(4) and 9 x 10(4)/ml) respectively sporulation of these fungi counted in L. inermis plant extract medium.