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The present work aimed to evaluate some technological characteristics of the wood of two commercial hybrid clones of Eucalyptus spp and two hybrid clones of Corymbia spp, implanted in three different planting spacings, at 24 months of age. Four trees per clone were sampled at each spacing to determine the following wood characteristics: basic density, gross calorific value, energy density and cellulose, hemicellulose, lignin, ash and carbon contents. There was a significant effect of the clone x spacing interaction for the basic density, energy density, lignin and cellulose contents of the wood. Eucalyptus showed the highest levels of lignin and cellulose, and hybrid clones of Corymbia the highest values of basic density and energy density of wood, with emphasis on clone C3, where the highest averages of the study were verified. For the levels of hemicelluloses and ash in the wood, the clone effect and spacing effect were observed. As for the carbon content and the gross calorific value in the wood, there was no significant effect, either from the clone, the spacing or the interaction of these two factors. The results show that there is variability in the characteristics between the genetic materials evaluated and in relation to the planting spacing tested. It should be noted that the choice of the best genetic material should be based on the technological characteristics of the wood, but also the forest productivity associated with good silviculture of the species should be evaluated.

Disease-resistant genes play an important role in defending against a variety of pathogens and insect pests in plants. Most of the disease-resistant genes encode proteins with conserved leucine rich repeat and nucleotide binding site domains. In this study, we cloned and characterized gene-resistant analogs (RGAs) from Eucalyptus grandis using degenerate PCR, with primers specifically targeting these two domains. The amplified fragments were cloned into the pGEM-T vector and transformed into Escherichia coli. Among the 90 clones obtained, 13 were sequenced and compared with each other and with previously identified gene-resistant diseases. A BLASTX search in GenBank revealed high similarities among the conserved domains of these cloned genes with RGA genes. Some clones, however, showed no significant similarity with DNA sequences in GenBank. Southern blotting analysis identified several polymorphic RFLP loci between distinct genotypes. However, none of them co-segregated with the Puccinia psidii Winter resistance gene 1 (Ppr1) in a population study.

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Thaumastocoris peregrinus is a pest that damages eucalyptus plantations. Recently in Brazil, there are few studies related to its control. With the advancement of molecular biology, several techniques can assist in the discovery of an effective and sustainable control. The different techniques of analysis of gene expression start with the extraction of the total RNA from the material for genomic analysis, hence it is essential that the RNA be intact. Numerous insect RNA extraction protocols are available, but none of them are widely effective, therefore, several factors and intrinsic characteristics of the tissue to be analyzed can affect the quality of the extracted material. Thus, it is necessary to modify the protocols in order to optimize the extraction of RNA. This study aimed to analyze the efficiency of three methods for RNA extraction from T. peregrinus. The results obtained demonstrated that the RNA extracted with only one method was more efficient due to less contamination with DNA and greater integrity of the samples. It should be noted that the determination of an efficient protocol for the extraction of RNA from T. peregrines will assist in future research, which will assist in the discovery of genes present in the extracted RNA sample.