Powdery mildew of rubber tree caused by Oidium heveae is an important disease of rubber plantations worldwide. Identification and classification of this fungus is still uncertain because there is no authoritative report of its morphology and no record of its teleomorphic stage. In this study, we compared five specimens of the rubber powdery mildew fungus collected in Malaysia, Thailand, and Brazil based on morphological and molecular characteristics. Morphological results showed that the fungus on rubber tree belongs to Oidium subgen. Pseudoidium. Nucleotide sequence analysis of the ribosomal DNA internal transcribed spacer (ITS) region and the large subunit rRNA gene (28S rDNA) were conducted to determine the relationships of the rubber powdery mildew fungus and to link this anamorphic fungus with its allied teleomorph. The results showed that the rDNA sequences of the two specimens from Malaysia were identical to a specimen from Thailand, whereas they differed by three bases from the two Brazilian isolates: one nucleotide position in the ITS2 and two positions in the 28S sequences. The ITS sequences of the two Brazilian isolates were identical to sequences of Erysiphe sp. on Quercus phillyraeoides collected in Japan, although the 28S sequences differed at one base from sequences of this fungus. Phylogenetic trees of both rDNA regions constructed by the distance and parsimony methods showed that the rubber powdery mildew fungus grouped with Erysiphe sp. on Q. phillyraeoides with 100% bootstrap support. Comparisons of the anamorph of two isolates of Erysiphe sp. from Q. phillyraeoides with the rubber mildew did not reveal any obvious differences between the two powdery mildew taxa, which suggests that O. heveae may be an anamorph of Erysiphe sp. on Q. phillyraeoides. Cross-inoculation tests are required to substantiate this conclusion.

Bone loss is a common problem after accidental traumas, cancers, congenital defects, and surgical procedures. The techniques normally used in large bone restoration involve complex and invasive procedures such as grafting. Thus, it is of interest to develop alternatives such as bioactive materials to induce accelerated bone regeneration. Natural rubber (NR) membranes are potential candidates due to their characteristics such as biocompatibility, angiogenic potential, flexibility, mechanical stability, surface porosity, and permeability. The present study aims at assessing the osteogenic potential of NR membranes of clones of high bioactivity of Hevea brasiliensis (RRIM 600 and IAN 873) and of Hancornia speciosa, as well as Physicochemical characterization at the NR membranes by scanning electron microscopy, Fourier transform infrared spectroscopy, and tensile tests. Critical-size bone defects were surgically made in adult male rabbit calvarium. A fibrin sealant (FS) was used to fix the membranes as a replacement for cyanoacrylate. We compared the respective osteogenic potentials of the tested membranes against a control group in healthy animals. The new bone formed was characterized using radiography, x-ray tomography, and histological and morphometric studies. Our results show that both membranes have great potential for regenerating bone tissue, with higher bioactivity compared to the gold standard (PTFE), which was used as positive control. In both NR membranes the stress-strain profile shows low stress at small strain, characteristic of elastomer with a low degree of reticulation, followed by an increase in the stress at high deformation and two main differences between both NRL biomembranes, related to its composition. The FS acted satisfactorily in the tests, being highly recommended as a substitute for cyanoacrylate in this type of application.

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