Gynostegium morphology of Mesechiteae miers (Apocynaceae, Apocynoideae) as it pertains to the classification of the tribe

In order to investigate morphological patterns in Mesechiteae and test the new circumscription of the tribe, the gynostegium structure of nine species belonging to Forsteronia, Mandevilla, and Mesechites, with two species from Secondatia as outgroup, were comparatively studied. Our results support the most recent circumscription of Mesechiteae, including Forsteronia, Mandevilla, and Mesechites and excluding Secondatia. The gynostegia of Forsteronia, Mandevilla, and Mesechites have the same basic organization: a proliferation of parenchyma cells in the style head forms five projecting ribs that are adnate to an expanded portion of the connective below the thecae, here named the 'staminal retinacle'. This adnation is very tenuous in Forsteronia ( few cells of the staminal retinacle are effectively connected to the style head) but much stronger in Mandevilla and Mesechites (several cells of the staminal retinacle are connected to the style head). The observed differences in the size of the style head ribs and the degree of adnation to the stamens also support the three major clades recognized within the tribe. The gynostegium of Secondatia has a different organization, of the type reported for representatives of the tribe Apocyneae: the style head has no projecting ribs, and its epidermal cells are interdigitated with, but not adnate to, unicellular trichomes of the staminal retinacle.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.1687999101

Production of calcium oxalate crystals by the basidiomycete Moniliophthora perniciosa, the causal agent of Witches' Broom disease of cacao

Oxalic acid has been shown as a virulence factor for some phytopathogenic fungi, removing calcium from pectin and favoring plant cell wall degradation. Recently, it was published that calcium oxalate accumulates in infected cacao tissues during the progression of Witches' Broom disease (WBD). In the present work we report that the hemibiotrophic basidiomycete Moniliophthora perniciosa, the causal agent of WBD, produces calcium oxalate crystals. These crystals were initially observed by polarized light microscopy of hyphae growing on a glass slide, apparently being secreted from the cells. The analysis was refined by Scanning electron microscopy and the compositon of the crystals was confirmed by energy-dispersive x-ray spectrometry. The production of oxalate by M. perniciosa was reinforced by the identification of a putative gene coding for oxaloacetate acetylhydrolase, which catalyzes the hydrolysis of oxaloacetate to oxalate and acetate. This gene was shown to be expressed in the biotrophic-like mycelia, which in planta occupy the intercellular middle-lamella space, a region filled with pectin. Taken together, our results suggest that oxalate production by M. perniciosa may play a role in the WBD pathogenesis mechanism.56436337

Flavonoid Supplementation Reduces the Extractive Content and Increases the Syringyl/Guaiacyl Ratio in Eucalyptus grandis x Eucalyptus urophylla Hybrid Trees

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The Eucalyptus genus plays an important role in the worldwide forest industry, with highly productive plantations supplying high-quality raw material for pulp and paper, wood, and biomass that would otherwise come from native forests. Lignin and extractives are important components for wood structure and protection but they are disruptive elements with respect to some industrial processes involving paper, pulp, and biomass production. This work evaluated effects of supplementation of flavonoids on the wood composition of Eucalyptus grandis x Eucalyptus urophylla (E. urograndis), a commercial hybrid. The wood samples were analyzed for extractives and lignin contents by wet chemical analysis, and the composition of lignin monomers and the carbohydrate hexosan/pentosan ratio were determined by analytical pyrolysis. The results showed that supplementation with the flavonoids naringenin and naringenin-chalcone led to an overall reduction of the extractive content and altered the monomeric composition of lignins towards a higher syringyl content. Thus, the treatment of Eucalyptus with flavonoids results in the improvement of wood quality for technological purposes.8217471757Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundacaopara a Ciencia e Tecnologia (Portugal) [P-KBBE/AGR-GPL/0001/2010, PTDC/AGR-GPL/098179/2008]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundacaopara a Ciencia e Tecnologia (Portugal) [P-KBBE/AGR-GPL/0001/2010, PTDC/AGR-GPL/098179/2008

A potential role for an extracellular methanol oxidase secreted by Moniliophthora perniciosa in Witches' broom disease in cacao

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The hemibiotrophic basidiomycete fungus Moniliophthora perniciosa, the causal agent of Witches' broom disease (WBD) in cacao, is able to grow on methanol as the sole carbon source. In plants, one of the main sources of methanol is the pectin present in the structure of cell walls. Pectin is composed of highly methylesterified chains of galacturonic acid. The hydrolysis between the methyl radicals and galacturonic acid in esterified pectin, mediated by a pectin methylesterase (PME), releases methanol, which may be decomposed by a methanol oxidase (MOX). The analysis of the M. pernciosa genome revealed putative max and pme genes. Real-time quantitative RT-PCR performed with RNA from mycelia grown in the presence of methanol or pectin as the sole carbon source and with RNA from infected cacao seedlings in different stages of the progression of WBD indicate that the two genes are coregulated, suggesting that the fungus may be metabolizing the methanol released from pectin. Moreover, immunolocalization of homogalacturonan, the main pectic domain that constitutes the primary cell wall matrix, shows a reduction in the level of pectin methyl esterification in infected cacao seedlings. Although MOX has been classically classified as a peroxisomal enzyme, M. perniciosa presents an extracellular methanol oxidase. Its activity was detected in the fungus culture supernatants, and mass spectrometry analysis indicated the presence of this enzyme in the fungus secretome. Because M. pernciosa possesses all genes classically related to methanol metabolism, we propose a peroxisome-independent model for the utilization of methanol by this fungus, which begins with the extracellular oxidation of methanol derived from the demethylation of pectin and finishes in the cytosol. (C) 2012 Elsevier Inc. All rights reserved.4911922932Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq [472710/2008-7]FAPESP [2006/59843-3, 2007/51030-6, 2009/50119-9