Fungi are disease-causing agents in plants and affect crops of economic importance. One control method is to induce resistance in the host by using biological control with hypovirulent phytopathogenic fungi. Here, we report the detection of a mycovirus in a strain of Colletotrichum gloeosporioides causing anthracnose of cashew tree. The strain C. gloeosporioides URM 4903 was isolated from a cashew tree (Anacardium occidentale) in Igarassu, PE, Brazil. After nucleic acid extraction and electrophoresis, the band corresponding to a possible double-stranded RNA (dsRNA) was purified by cellulose column chromatography. Nine extrachromosomal bands were obtained. Enzymatic digestion with DNAse I and Nuclease S1 had no effect on these bands, indicating their dsRNA nature. Transmission electron microscopic examination of extracts from this strain showed the presence of isometric particles (30-35 nm in diameter). These data strongly suggest the infection of this C. gloeosporioides strain by a dsRNA mycovirus. Once the hypovirulence of this strain is confirmed, the strain may be used for the biological control of cashew anthracnose. Key words: Anacardium occidentale, anthracnose, biological control, hypovirulence, mycovirus, phytopathogenic fungi.Fungi are the most important disease-causing agents in plants with serious economic impact. Chemical methods to control phytopathogenic fungi can affect human health and have environmental consequences. In an attempt to minimize dependence on chemical methods, alternative means of pathogen control have been investigated (Yu et al., 2010). One alternative is to use hypovirulent phytopathogenic fungal strains that can biologically control phytopathogenic fungi of the same or related species. Fungal hypovirulence is usually caused by mycoviral infection. Hypovirulent fungi cause milder infection and may induce hypovirulence in other pathogenic strains via viral transfer (Pearson et al., 2009).All currently known mycoviruses have isometric, double-stranded RNA (dsRNA)-containing particles, and are classified into three families: Chrysoviridae, Endornaviridae, Partitiviridae and Totiviridae. Particle size ranges from 25 to 50 nm in diameter, except for endornaviruses which do not produce virions (Chu et al., 2002;Ghabrial & Suzuki, 2009).In this communication, we report the presence of isometric dsRNA viral particles in a strain of Colletotrichum gloeosporioides (Penz.) Sacc., the causal agent of anthracnose in cashew tree.Colletotrichum gloeosporioides URM 4903 was isolated from anthracnose lesions on a cashew tree (Anacardium occidentale L.) in the town of Igarassu, Pernambuco, Brazil (7°50'3.74"S and 34°54'22.87"O), and deposited in the mycology collection (URM) at Federal University of Pernambuco, Recife, PE. This strain was chosen after preliminary tests revealed poor pathogenicity in detached cashew leaves and the presence of extrachromosomal bands in agarose gel electrophoresis (unpublished data).PDA (20% potato extract, 2% dextrose, 1.5% agar) and PD (20% potato extract,...

The Abnc strain of A. nidulans carries the bncA1 gene (binucleated conidia), which induces the formation of binucleate and trinucleate conidia, displaying a chromosome I duplicated area and shifted to the chromosome II (IàII), and bringing forth genetic instability with degenerated sectors. This work has considered in a cytological level the conidiogenesis of the deteriorated variants isolated from the Abnc strain of A. nidulans, observing the event at the level of structural alterations, which composes the conidiophore, and the variations in the number of sterigmata and conidia nuclei. Cytogenetic analyses of conidiogenesis were accomplished in predetermined periods, under Giemsa stain, to observe the nuclei and analysis through the Scanning Electronic Microscopy, and also the structures that composes the conidiophore. The analyzed, deteriorated variants presented alterations in the cell-foot, metulae and phialides structure, conidiophore number and conidias reduction, and the formation of secondary conidiophores. These alterations can be related to genes for the development, bristle, and activities of NIMA e NINX cdc2 (involved in morphogenesis regulatory cycle) that induce the expression of brislte, establishing the link to the regulation and expression of the genes control throughout the conidiophore development. Key words: bristle, conidiophore, developmental mutants CONIDIOGÊNESE DE VARIANTES DETERIORADOS DA LINHAGEM Abnc DE Aspergillus nidulansRESUMO: A linhagem Abnc de A. nidulans é portadora do gene bncA1 ("binucleated conidia"), que confere a característica de conídios bi e trinucleados, além de apresentar uma região duplicada do cromossomo I e translocada para o cromossomo II (IàII), gerando instabilidade genética com formação de setores deteriorados. Este trabalho analisou citologicamente a conidiogênese dos variantes deteriorados isolados da linhagem Abnc de A. nidulans, observando a ocorrência de alterações das estruturas que compõe o conidióforo e as variações no número de núcleos dos esterígmas e conídios. As análises citogenéticas da conidiogênese foram realizadas com períodos pré-determinados, sendo efetuada a coloração de Giemsa para observação dos núcleos, e análise por Microscopia Eletrônica de Varredura, para observação das estruturas que compõe o conidióforo. Os variantes deteriorados analisados apresentaram alterações na estrutura das células-pé, métulas e fiálides, redução do número de conidióforos e conídios, e formação de conidióforos secundários. Estas alterações no conidióforo podem estar relacionadas com os genes para o desenvolvimento, bristle e com atividade das proteínas NIMA e NINX cdc2 (envolvidas com o ciclo regulatório da morfogênese) as quais induzem a expressão de brislte, estabelecendo o caminho para a regulação e controle da expressão dos genes durante o desenvolvimento do conidióforo.

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A development mutant, named V103, was obtained spontaneously from the A strain of A. nidulans. The A strain contains a duplicated segment of chromosome I that has undergone translocation to chromosome II (I II). It is mitotically unstable and generates phenotypically deteriorated types, some with enhanced stability. The deteriorated variants of A. nidulans show abnormal development, exhibiting slower colony growth, variations in colony pigmentation and changes in conidiophore structure. The alterations observed in the conidiophore include fewer metulae and phialides, further elongation and ramification of these structures, delayed nuclear migration and the presence of secondary conidiophores.