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      Características culturais e severidade da mancha foliar de Quambalaria eucalypti sob diferentes regimes de temperatura, luz e período de molhamento foliar Translated title: Cultural characteristics and severity of the Quambalaria eucalypti leaf spot under different temperatures, light regimes and leaf wetness duration

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          Abstract

          Quambalaria eucalypti foi recentemente relatado como agente etiológico da mancha foliar e do anelamento da haste de Eucalyptus spp., no Brasil. Em vista do pouco conhecimento disponível sobre este patossistema, procurou-se, neste trabalho, avaliar o crescimento micelial e a esporulação do fungo em diferentes meios de cultura, determinar "in vitro" a temperatura ótima para o crescimento micelial, esporulação e a germinação de conídios, avaliar a influência do regime de luz sobre a germinação de conídios e determinar a influência do binômio temperatura - tempo de câmara úmida sobre a severidade da doença. As temperaturas de 25, 13 e 37 ºC foram respectivamente, ótima, mínima e máxima, para o crescimento. A temperatura ótima para esporulação foi de 25 ºC. A interação entre meios de cultura e isolados foi significativa, sendo que os meios de batata-dextrose-ágar (BDA), V8-ágar (V8) e caldo de vegetais-ágar foram os mais favoráveis ao crescimento micelial, seguidos de caseína hidrolizada ágar e ágar água. Todavia, para a esporulação, a interação entre meios de cultura e isolados não foi significativa e o meio de BDA foi o mais favorável à esporulação do patógeno. A temperatura e o regime de luz não afetaram significativamente a germinação de conídios, com uma taxa média de 85 % de germinação. A interação entre temperatura e tempo de permanência em câmara úmida não foi significativa para severidade da doença. O modelo quadrático foi o que melhor representou a severidade em função da temperatura, com ponto ótimo estimado igual a 27 ºC. O modelo exponencial foi o que melhor representou a severidade em função do tempo de câmara úmida.

          Translated abstract

          Quambalaria eucalypti was recently reported as the causal agent of leaf spot and stem curl in Eucalyptus spp. in Brazil. Given the scarcity of knowledge available on this pathosystem our objectives were to evaluate the "in vitro" mycelial growth and sporulation of this fungus in different culture media, determine the optimum temperature of mycelial growth, sporulation and conidial germination, evaluate the influence of the lighting regime on conidial germination and determine the combined influence of time and temperature in a moisture chamber on the disease severity. Temperatures of 25, 13 and 37 ºC were found to be the optimum, minimum and maximum for growth, respectively. The optimum temperature for sporulation was 25 ºC. The interaction between growth medium and isolates was significant and potato dextrose-agar (PDA), V8-agar (V8) and vegetable broth-agar produced the most mycelial growth, followed by hydrolyzed casein-agar and water-agar. On the other hand, the interaction between culture medium and isolates was not significant for sporulation, although PDA appeared to favor spore production by this pathogen. Temperature and lighting regime did not significantly affect conidial germination, with 85 % of medium rate. The interaction between temperature and time of exposition in a moisture chamber was not significant for severity of disease. A quadratic model best represented disease severity as a function of temperature, with estimated optimum 27 ºC. An exponential model best represented disease severity as a function of moisture chamber.

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          Plant Pathology

          This fifth edition of the classic textbook in plant pathology outlines how to recognize, treat, and prevent plant diseases. It provides extensive coverage of abiotic, fungal, viral, bacterial, nematode and other plant diseases and their associated epidemiology. It also covers the genetics of resistance and modern management on plant disease. Plant Pathology, Fifth Edition , is the most comprehensive resource and textbook that professionals, faculty and students can consult for well-organized, essential information. This thoroughly revised edition is 45% larger, covering new discoveries and developments in plant pathology and enhanced by hundreds of new color photographs and illustrations. The latest information on molecular techniques and biological control in plant diseases Comprehensive in coverage Numerous excellent diagrams and photographs A large variety of disease examples for instructors to choose for their course
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            Natural variation in the Arabidopsis response to the avirulence gene hopPsyA uncouples the hypersensitive response from disease resistance.

            The plant hypersensitive response (HR) is tightly associated with gene-for-gene resistance and has been proposed to function in containing pathogens at the invasion site. This tight association has made it difficult to unequivocally evaluate the importance of HR for plant disease resistance. Here, hopPsyA from Pseudomonas syringae pv. syringae 61 is identified as a new avirulence gene for Arabidopsis that triggers resistance in the absence of macroscopic HR. Resistance to P. syringae pv. tomato DC3000 expressing hopPsyA was EDS1-dependent and NDR1-independent. Intriguingly, several Arabidopsis accessions were resistant to DC3000(hopPsyA) in the absence of HR. This is comparable to the Arabidopsis response to avrRps4, but it is shown that hopPsyA does not signal through RPS4. In a cross between two hopPsyA-resistant accessions that differ in their HR response, the HR segregated as a recessive phenotype regulated by a single locus. This locus, HED1 (HR regulator in EDS1 pathway), is proposed to encode a protein whose activity can cause suppression of the EDS1-dependent HR signaling pathway. HED1-regulated symptomless gene-for-gene resistance responses may explain some cases of Arabidopsis resistance to bacteria that are classified as nonhost resistance.
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              Manual de utilização do programa SAEG: Sistema para Análises Estatísticas e Genéticas

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                Author and article information

                Journal
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                Fitopatologia Brasileira
                Fitopatol. bras.
                Sociedade Brasileira de Fitopatologia (Brasília, DF, Brazil )
                0100-4158
                1678-4677
                August 2007
                : 32
                : 4
                : 329-334
                Affiliations
                [01] Viçosa MG orgnameUniversidade Federal de Viçosa orgdiv1Departamento de Fitopatologia Brasil aalfenas@ 123456ufv.br
                Article
                S0100-41582007000400007 S0100-4158(07)03200407
                10.1590/S0100-41582007000400007
                5fae968d-d093-4ce5-9b2c-3cbf5644774e

                This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

                History
                : 23 February 2006
                : 30 March 2007
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 21, Pages: 6
                Product

                SciELO Brazil

                Categories
                Artigos

                luz,molhamento foliar,meio de cultura,mancha foliar,anelamento da haste de eucalipto,light,leaf wetness,culture media,eucalyptus leaf spot,stem curl,Eucalyptus,temperatura,temperature

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