Time‐Dependent Sporulation, Conidial Size and Germ Tube Formation in <i>Alternaria tenuissima</i> (Kunze ex Pers.) Wiltshire on Different Media

Sarma, B. K.

doi:10.1046/j.1439-0434.2000.00537.x

Cited by 2 publications

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“…Diversos meios de cultura que favorecem o crescimento micelial e estimulam a esporulação de espécies de Alternaria têm sido relatados na literatura. Entre eles se destacam os meios de aveia-ágar (LEITE; AMORIM, 2002;TUITE, 1969;QUEIROZ; BATISTA; BROMMNSCHENKEL, 2004) e o de batata-dextrose-ágar (BDA), freqüentemente utilizados para estudos de crescimento e esporulação (ALLEN; BROWN; KOCHMAN, 1983b;ÁVILA et al, 2000;COTTY;MISAGHI, 1985;FOURTOUNI;MANETAS;CHRISTIAS, 1998;HOTCHKISS;BAXTER, 1983;LACY;BRIDGMAN, 1962;SHABANA;ELWAKIL;CHARUDATTAN, 2001;SHAHIN;SHEPARD, 1979;SINGH, U.;SINGH, S., SARMA, 2000;STRANDBERG, 1987;TEIXEIRA et al, 2001). Mas Diener (1952) Muitos fungos ou alguns isolados que não esporulavam em meio BDA passaram a esporular nesse meio.…”

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Crescimento e esporulação de >i<Alternaria dauci>/i< e >i<A. solani>/i< em meio de cultura

Pulz¹

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Growth and sporulation of Alternaria dauci e Alternaria solani in culture mediaAlternaria dauci and A. solani are two phytopathogenic fungus species known for difficult sporulation in culture media. This hampers artificial inoculations and, consequently, affects the selection process of carrot and tomato genotypes resistant to the diseases caused by these fungi. This study had the objective of verifying the influence of some factors applied during incubation on mycelia growth and sporulation of the two fungus species. Different culture media (BDA, oat and V8), temperature (15, 20, 25, 30 and 35 ºC), light wavelengths during incubation (yellow, blue, white, NUV, green, and red), stress types applied to the colony (scratching, UV, microwave irradiation, and temperature of 100 ºC) and photoperiods (light / dark, respectively, of 24 h / 0 h, 22 h / 2 h, 17 h / 7 h, 12 h / 12 h, 7 h / 17 h, 2 h / 22 h and 0 h / 24 h) were tested. Upon determination of the best factors, the method developed in this study was compared to the traditional procedure (BDA, 25 ºC, 12 h white / 12 h dark light and scratching of the colony), with different isolates of both species. Results indicated the V8-agar media and a temperature of 25 ºC as most favorable for growth and sporulation. The different wavelengths had a marked influence on sporulation and NUV was the most stimulating. All applied stress types induced sporulation, but best results were obtained with scratching of the colonies. The 12 h light / 12 h dark photoperiod stimulated sporulation most. In general, longer dark than light periods after the stress of the colony favored sporulation. The procedure developed in this study consisted of incubation in V8-agar media, a temperature of 25 ºC, scratching of the colony and a 12 h light / 12 h dark photoperiod. This process is clearly superior to the traditional method for growth and sporulation of both species.

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Crescimento e esporulação de >i<Alternaria dauci>/i< e >i<A. solani>/i< em meio de cultura

Pulz¹

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Conidial morphology, virulence, molecular characterization, and host–parasite interactions of selected Alternaria panax isolates on American ginseng

2005

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The fungus Alternaria panax Whetzel causes leaf and stem blight of American ginseng ( Panax quinquefolius L.). Six isolates of A. panax, collected from widely separated ginseng-growing areas in North America, were characterized on the basis of their colony and conidial morphology, molecular characteristics, and virulence. Colony morphology on standard media and conidial morphology based on light microscopy showed some variation with geographic locality: Wisconsin isolates were slightly different from Ontario and British Columbia isolates. Isolates from each locality were equally virulent on American ginseng. Ginseng phytotoxin was present in the conidial germination fluid of all isolates. Sequences of the β-tubulin gene from all six isolates were identical as were the sequences of the internal transcribed spacer (ITS) region of the rDNA gene. The ITS1 and ITS2 gene sequences of the six isolates were also identical to those of American and Korean isolates of A. panax deposited in GenBank. Cellulase and pectinase were detected by agar biodiffusion assays of a representative isolate. Germination of conidia of this isolate on ginseng leaflets began within 2 h of application to leaf surfaces, and over 80% of conidia germinated within 12 h of application. Conidia produced one to several germ tubes that grew in all directions over the leaflet surface. The germ tubes formed terminal appressoria over stomatal openings, epidermal cells, and epidermal cell junctions. The frequency of direct penetration into ginseng leaflets was greater than penetration through stomata. Both retraction of plasma membrane and disruption of chloroplast membranes were observed 12 h after leaflet inoculation. At 24 h after inoculation, hyphae were present in both intercellular spaces and inside mesophyll cells. Severe disruption of plasma membrane, chloroplasts, and mitochondria was observed between 24 and 48 h after inoculation.

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Time‐Dependent Sporulation, Conidial Size and Germ Tube Formation in Alternaria tenuissima (Kunze ex Pers.) Wiltshire on Different Media

Cited by 2 publications

References 9 publications

Crescimento e esporulação de >i<Alternaria dauci>/i< e >i<A. solani>/i< em meio de cultura

Crescimento e esporulação de >i<Alternaria dauci>/i< e >i<A. solani>/i< em meio de cultura

Conidial morphology, virulence, molecular characterization, and host–parasite interactions of selected Alternaria panax isolates on American ginseng

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