These results indicate that X-ray radiation emitted during panoramic dental radiography induces a genotoxic effect on epithelial gingival cells that increases the frequency of chromosomal damage and nuclear alterations indicative of apoptosis.

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This study reports on expression analysis associated with molecular systems biology of cacao-Moniliophthora perniciosa interaction. Gene expression data were obtained for two cacao genotypes (TSH1188, resistant; Catongo, susceptible) challenged or not with the fungus M. perniciosa and collected at three time points through disease. Using expression analysis, we identified 154 and 227 genes that are differentially expressed in TSH1188 and Catongo, respectively. The expression of some of these genes was confirmed by RT-qPCR. Physical protein-protein interaction (PPPI) networks of Arabidopsis thaliana orthologous proteins corresponding to resistant and susceptible interactions were obtained followed by cluster and gene ontology analyses. The integrated analysis of gene expression and systems biology allowed designing a general scheme of major mechanisms associated with witches' broom disease resistance/susceptibility. In this sense, the TSH1188 cultivar shows strong production of ROS and elicitors at the beginning of the interaction with M. perniciosa followed by resistance signal propagation and ROS detoxification. On the other hand, the Catongo genotype displays defense mechanisms that include the synthesis of some defense molecules but without success in regards to elimination of the fungus. This phase is followed by the activation of protein metabolism which is achieved with the production of proteasome associated with autophagy as a precursor mechanism of PCD. This work also identifies candidate genes for further functional studies and for genetic mapping and marker assisted selection.

White-rot basidiomycetes are the organisms that decompose lignin most efficiently, and is a promising species for ligninolytic enzyme production. There are several publications on applications for lignin degradation regarding the expression and secretion of laccase and manganese peroxidase (MnP) but no reports on the identification and characterization of lignin peroxidase (LiP), a relevant enzyme for the efficient breakdown of lignin. The object of this study was to identify and partially characterize, for the first time, gDNA, mRNA, and the corresponding lignin peroxidase (TvLiP) protein from strain CCMB561 from the Brazilian semiarid region. The presence of ligninolytic enzymes produced by this strain grown in inducer media was qualitatively and quantitatively analyzed by spectrophotometry, qPCR, and dye fading using Remazol Brilliant Blue R. The spectrophotometric analysis showed that LiP activity was higher than that of MnP. The greatest LiP expression as measured by qPCR occurred on the 7 day, and the ABSA medium (agar, sugarcane bagasse, and ammonium sulfate) was the best that favored LiP expression. The amplification of the gene median region covering approximately 50% of the gene (87% identity); the presence of Trp199, Leu115, Asp193, Trp199, and Ala203 in the translated amplicon of the mRNA; and the close phylogenetic relationship between TvLiP and LiP all indicate that the target enzyme is a lignin peroxidase. Therefore, CCMB561 has great potential for use as a LiP, MnP, and Lac producer for industrial applications.

ABSTRACT. Cacao (Theobroma cacao) is one of the most important tropical crops; however, production is threatened by numerous pathogens, including the hemibiotrophic fungus Moniliophthora perniciosa, which causes witches' broom disease. To understand the mechanisms that lead to the development of this disease in cacao, we focused our attention on cacao transcription factors (TFs), which act as master regulators of cellular processes and are important for the finetuning of plant defense responses. We developed a macroarray with 88 TF cDNA from previously obtained cacao-M. perniciosa interaction libraries. Seventy-two TFs were found differentially expressed between the susceptible (Catongo) and resistant (TSH1188) genotypes and/or during the disease time course -from 24 h to 30 days after infection. Most of the differentially expressed TFs belonged to the bZIP, MYB and WRKY families and presented opposite expression patterns in susceptible and resistant cacao-M. perniciosa interactions (i.e., upregulated in Catongo and down-regulated in TSH1188). The results of the macroarray were confirmed for bZIP and WRKY TFs by realtime PCR. These differentially expressed TFs are good candidates for subsequent functional analysis as well as for plant engineering. Some of these TFs could also be localized on the cacao reference map related to witches' broom resistance, facilitating the breeding and selection of resistant cacao trees.

We identified and characterized two chitinases, named MpCHIT1 and MpCHIT2, from the fungus Moniliophthora perniciosa - the etiologic agent of witches' broom disease in cacao tree (Theobroma cacao L.) - during its development, mainly in the mycelia phases preceding the basidioma formation. The expression of MpCHIT1 and MpCHIT2, together with MpCHS and MpATG8 (chitin synthase and autophagy genes, respectively), was analyzed during the M. perniciosa growth and development on bran-based solid medium as well as in liquid medium containing H2O2 or rapamycin (oxidative and nutritional related-autophagy stress agents, respectively). In order to link the expression of chitin metabolism-related genes to nutritional composition influencing fungus development, we also quantified total and reduced sugars, as well as macro- and micronutrients in the bran-based solid medium. The expression analysis showed that the MpCHS expression increased through mycelial development and then decreased in the primordium and basidioma phases, while the expression of MpCHIT1 and MpCHIT2 was higher in basidioma and primordium phases, respectively. Moreover, the expression pattern of MpCHIT1 and MpCHIT2 is distinct, the second correlated with the MpATG8 expression pattern and possibly with autophagy process, while the first may be related to the basidioma formation. The quantification of total and reduced sugars, as well as macro- and micronutrients supported the idea that the cell wall restructuration due to MpCHS, MpCHIT1 and MpCHIT2 is related to stress and fungal nutrient reallocation, allowing the formation and development of the basidioma. Experiments involving M. perniciosa growth on liquid medium containing H2O2 or rapamycin showed that MpCHIT1 and MpCHIT2 were over-expressed in response to oxidative but also to nutritional related-autophagy stresses. Interestingly, the expression level of MpCHS, MpCHIT1 and MpCHIT2 in presence of rapamycin is similar to the one observed in the primordium and basidioma from bran-based solid medium. The analysis of the overall data allowed designing a general scheme of chitin metabolism and autophagy during M. perniciosa development, focusing on the mycelium phases as crucial and environmentally influenced steps preceding the primordium and basidioma formation. These data support the idea that the nutritional environment of M. perniciosa influences its development and life cycle.