Early development of Moniliophthora perniciosa basidiomata and developmentally regulated genes

<p>Abstract</p> <p>Background</p> <p>The hemibiotrophic fungus <it>Moniliophthora perniciosa </it>is the causal agent of Witches' broom, a disease of <it>Theobroma cacao</it>. The pathogen life cycle ends with the production of basidiocarps in dead tissues of the infected host. This structure generates millions of basidiospores that reinfect young tissues of the same or other plants. A deeper understanding of the mechanisms underlying the sexual phase of this fungus may help develop chemical, biological or genetic strategies to control the disease.</p> <p>Results</p> <p>Mycelium was morphologically analyzed prior to emergence of basidiomata by stereomicroscopy, light microscopy and scanning electron microscopy. The morphological changes in the mycelium before fructification show a pattern similar to other members of the order <it>Agaricales</it>. Changes and appearance of hyphae forming a surface layer by fusion were correlated with primordia emergence. The stages of hyphal nodules, aggregation, initial primordium and differentiated primordium were detected. The morphological analysis also allowed conclusions on morphogenetic aspects. To analyze the genes involved in basidiomata development, the expression of some selected EST genes from a non-normalized cDNA library, representative of the fruiting stage <it>of M. perniciosa</it>, was evaluated. A macroarray analysis was performed with 192 selected clones and hybridized with two distinct RNA pools extracted from mycelium in different phases of basidiomata formation. This analysis showed two groups of up and down-regulated genes in primordial phases of mycelia. Hydrophobin coding, glucose transporter, Rho-GEF, Rheb, extensin precursor and cytochrome p450 monooxygenase genes were grouped among the up-regulated. In the down-regulated group relevant genes clustered coding calmodulin, lanosterol 14 alpha demethylase and PIM1. In addition, 12 genes with more detailed expression profiles were analyzed by RT-qPCR. One aegerolysin gene had a peak of expression in mycelium with primordia and a second in basidiomata, confirming their distinctiveness. The number of transcripts of the gene for plerototolysin B increased in reddish-pink mycelium and indicated an activation of the initial basidiomata production even at this culturing stage. Expression of the glucose transporter gene increased in mycelium after the stress, coinciding with a decrease of adenylate cyclase gene transcription. This indicated that nutrient uptake can be an important signal to trigger fruiting in this fungus.</p> <p>Conclusion</p> <p>The identification of genes with increased expression in this phase of the life cycle of <it>M. perniciosa </it>opens up new possibilities of controlling fungus spread as well as of genetic studies of biological processes that lead to basidiomycete fruiting. This is the first comparative morphologic study of the early development both <it>in vivo </it>and <it>in vitro </it>of <it>M. perniciosa </it>basidiomata and the first description of genes expressed at this stage of the fungal life cycle.</p

Identification of Climate and Genetic Factors That Control Fat Content and Fatty Acid Composition of \u3ci\u3eTheobroma cacao\u3c/i\u3e L. Beans

The main ingredients of chocolate are usually cocoa powder, cocoa butter, and sugar. Both the powder and the butter are extracted from the beans of the cacao tree (Theobroma cacao L.). The cocoa butter represents the fat in the beans and possesses a unique fatty acid profile that results in chocolate’s characteristic texture and mouthfeel. Here, we used a linkage mapping population and phenotypic data of 3,292 samples from 420 progeny which led to the identification of 27 quantitative trait loci (QTLs) for fatty acid composition and six QTLs for fat content. Progeny showed extensive variation in fat levels and composition, with the level of palmitic acid negatively correlated to the sum of stearic acid, oleic acid, and linoleic acid. A major QTL explaining 24% of the relative level of palmitic acid was mapped to the distal end of chromosome 4, and those higher levels of palmitic acid were associated with the presence of a haplotype from the “TSH 1188” parent in the progeny. Within this region of chromosome 4 is the Thecc1EG017405 gene, an orthologue and isoform of the stearoyl-acyl carrier protein (ACP) desaturase (SAD) gene in plants, which is involved in fatty acid biosynthesis. Besides allelic differences, we also show that climate factors can change the fatty acid composition in the beans, including a significant positive correlation between higher temperatures and the higher level of palmitic acid. Moreover, we found a significant pollen donor effect from the variety “SIAL 70” which was associated with decreased palmitic acid levels

Characterization of lactobacilli strains derived from cocoa fermentation in the south of Bahia for the development of probiotic cultures

In the last years, several factors have contributed to the development of probiotic cultures from locally sourced strains. In this paper, we aimed to characterize Lactobacillus plantarum and Lactobacillus fermentum isolates derived from Brazilian cocoa fermentation for the development of new probiotic cultures. Isolates diversity was studied by RAPD and strains were further tested in vitro for their probiotic potential. Physiological traits such as heat tolerance, hydrophobicity, resistance to simulated gastrointestinal digestion and antibiotic susceptibility were studied. Besides, activity against food pathogens was tested through four different assays: deferred inhibition, co-aggregation, co-cultivation and antagonism of supernatants. Considering the resistance to simulated gastrointestinal digestion and the results from the antimicrobial and co-aggregation tests, L. plantarum 286 showed the most promising results, followed by L. plantarum 289, for further studies for their application as probiotics.Fil: Teles Santos, Tiza. Universidade Estadual de Santa Cruz; BrasilFil: Santos Ornelas, Roberta María. Universidade Estadual de Santa Cruz; BrasilFil: Borges Arcucio, Leonardo. Universidade Federal de Minas Gerais; BrasilFil: Messias Oliveira, Mayara. Universidade Estadual de Santa Cruz; BrasilFil: Nicoli, Jaques Robert. Universidade Federal de Minas Gerais; BrasilFil: Villela Dias, Cristiano. Universidade Estadual de Santa Cruz; BrasilFil: Trovatti Uetanabaro, Ana Paula. Universidade Estadual de Santa Cruz; BrasilFil: Vinderola, Celso Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentin