Pythium aphanidermatum pathogenicity to hydroponics lettuce and its biocontrol with Trichoderma

O objetivo deste trabalho foi avaliar a patogenicidade de Pythium aphanidermatum a variedades de alface, e a ação do produto Biotrich, formulado com Trichoderma, no controle deste patógeno e na promoção do crescimento das plantas. Em experimento in vitro, plântulas recém-germinadas das variedades de alface Vera e Elisa foram colocadas em placas de Petri com ágar-água e 1 mL de suspensão do produto Biotrich (0,2 mL L-1) e, após 24 horas, em discos com micélio do isolado de Pythium. As avaliações foram realizadas após dez dias de incubação a 20 e 31ºC. Ostestes in vivo foram realizados na primavera e verão, em sistema hidropônico “Nutrient Film Technique” (NFT), em delineamento inteiramente casualizado, em esquema fatorial 2x2x2, como segue: duas variedades; presença ou ausência do patógeno; e presença ou ausência de Biotrich. Ao final do cultivo, foram avaliadas as massas de matéria fresca e seca das plantas. No experimento in vitro, P. aphanidermatum apresentou maior agressividade a 31ºC. Contudo, não foi verificada patogenicidade nos testes in vivo. De modo geral, o Biotrich não promoveu o crescimento das plantas, mas foi efetivo no controle do patógeno in vitro. Pythium aphanidermatum é patogênico às variedades de alface Vera e Elisa, a 20 e 31ºC, e o Biotrich é efetivo para o controle desse patógeno nessas temperaturas.The objective of this work was to evaluate the pathogenicity of Pythium aphanidermatum to lettuce varieties, and the action of the product Biotrich, formulated with Trichoderma, in the control of this pathogen and its effect on plant growth promotion. In a in vitro experiment, germinated seedlings of Vera and Elisa lettuce varieties were placed in Petri dishes with water-agar and 1mL Biotrich suspension (0.2 mL L-1), and after 24 hours, on plugs with the Pythium isolate mycelium. The evaluations were done ten days after the incubation at 20 and 31ºC. In vivo experiments were carried out during the spring and summer, using the Nutrient Film Technique (NFT) system, in a completely randomized design, following a 2x2x2 factorial arrangement, as well: two varieties; pathogen abscence or presence; and with or without Biotrich addition. At the end of cultivation, the fresh and dry weight of shoots and roots were analyzed. In vitro, P. aphanidermatum had increased aggressiveness at 31ºC. However, no pathogenicity was observed in vivo. Generally, Biotrich did not promote plant growth; however, it was effective in controlling the pathogen in vitro. Pythium aphanidermatum is pathogenic to lettuce varieties Vera and Elisa, at 20 and 31°C, and Biotrich is effective for its control at these temperatures

Fungal systematics and evolution : FUSE 7

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Morphological and phylogenetic analyses of three <I>Phytopythium</I> species (Peronosporales, Oomycota) from Brazil

We analyzed the morphology and phylogenetic placement of six isolates of Phytopythium belonging to P. helicoides, P. palingenes and P. vexans that were isolated from water bodies and substrates used for hydroponically grown crops. The molecular data are from the partial large subunit and the complete internal transcribed regions of the ribosomal DNA. These three species are characterized by the presence of ovoid to globose zoosporangia with papillae, internal proliferation as in Phytophthora and mode of zoospore discharge as in Pythium. All isolates showed high morphological and phylogenetic similarity with members of the Clades II and III of Phytopythium. In this paper, Phytopythium palingenes is included for the first time in phylogenetic analyses and our ITS and LSU phylogenies indicated that Aquaperonospora taiwanensis is a synonym of Phytopythium helicoides.</p

Oomycota (Straminipila) da Reserva Biológica de Paranapiacaba, Santo André, SP, Brasil

Durante o período de novembro/2003 a novembro/2004, coletas trimestrais de amostras de água e solo foram realizadas na Reserva Biológica de Paranapiacaba, importante fragmento de Mata Atlântica localizado no estado de São Paulo, para estudo da diversidade de oomicetos. Para o isolamento destes organismos, as amostras foram tratadas pelo método de iscagem, que resultou na identificação de 35 espécies, das quais uma pertence a Leptomitales, quatro a Peronosporales, duas a Rhipidiales, e 28 a Saprolegniales, sendo descritas, comentadas e ilustradas neste trabalho as de ocorrência relatada no Brasil, das quais três são citadas pela primeira vez para o estado de São Paulo, Leptolegnia eccentrica Coker &amp; Matthews, Pythiopsis humphreyana Coker e Pythiopsis irregularis Seymour, e 20 para a Reserva

Oomycota from &quot;Parque Estadual da Ilha do Cardoso&quot; (PEIC): first records for São Paulo State and Brazil

(Oomycota from “Parque Estadual da Ilha do Cardoso” (PEIC): first records for São Paulo State and Brazil). We studied the oomycetes diversity from soil and freshwater samples collected quarterly from August 2012 to June 2013 at “Parque Estadual da Ilha do Cardoso” (PEIC), São Paulo State, Brazil. Among the species identified by morphological and/or molecular (complete ITS rDNA region) analysis, four are recorded for the first time for Brazil: Araiospora streptandra var. streptandra Kevorkian, Achlya primoachlya (Coker &amp; Couch) TW Johnson and RL Seym., Aplanopsis terrestris Höhnk and Saprolegnia aenigmatica Sandoval-Sierra &amp; Diéguez-Uribeondo and three for São Paulo State: Achlya crenulata Ziegler, Brevilegnia longicaulis TW Johnson and Saprolegnia truncata RL Seym. All species are described, commented and illustrated herein. The specimens were deposited in the culture collection of the “Instituto de Botânica (CCIBt)” and/or in the Herbarium SP. The ITS rDNA sequences obtained were deposited in the GenBank.</p