Influence of Mycosphaerella and Teratosphaeria leaf diseases on chemical composition of essential oils of Eucalyptus globulus and effect of these essential oils on ascospores germination.

In a first step, essential oils were extracted from Eucalyptus globulus leaves, healthy and with symptoms and signs of Mycosphaerella leaf disease (MLD) and Teratosphaeria leaf disease (TLD), in two leaf stages. Stage 1: sessile, oval leaves covered by a waxy layer of a bluish colour, with opposite phyllotaxis, inserted along stems of quadrangular section. Stage 2: narrow and sickle leaves with a greyish green surface, mainly on the abaxial surface, inserted in alternating pairs along rounded stems. The essential oils were extracted by hydrodistillation and were analyzed by gas chromatography coupled with mass spectrometry. Chemical composition data and percentages of essential oil constituents were submitted to cluster analysis and principal component analysis. In a second step, under in vitro conditions, was evaluated the germination of Teratosphaeria nubilosa (one of the causal agents of TLD) ascospores in contact with the four types of essential oils extracted. The evaluations were performed at 24, 48 and 72 h after the experiments were assembled. The present study made it possible to distinguish and identify the chemical composition of essential oils from the eucalypt leaves used, and allowed 1,8-cineole to be identified as the major component for the essential oils investigated. The contact between essential oils and T. nubilosa spores allowed to prove the inhibition of the ascospores germination, being more efficient for the essential oils extracted from materials with the disease, which presented high amounts of 1,8-cineole.

Determination of disease biomarkers in Eucalyptus by comprehensive two-dimensional gas chromatography and multivariate data analysis.

In this paper is reported the use of the chromatographic profiles of volatiles to determine disease markers in plants - in this case, leaves of Eucalyptus globulus contaminated by the necrotroph fungus Teratosphaeria nubilosa. The volatile fraction was isolated by headspace solid phase microextraction (HS-SPME) and analyzed by comprehensive two-dimensional gas chromatography-fast quadrupole mass spectrometry (GC×GC-qMS). For the correlation between the metabolic profile described by the chromatograms and the presence of the infection, unfolded-partial least squares discriminant analysis (U-PLS-DA) with orthogonal signal correction (OSC) were employed. The proposed method was checked to be independent of factors such as the age of the harvested plants. The manipulation of the mathematical model obtained also resulted in graphic representations similar to real chromatograms, which allowed the tentative identification of more than 40 compounds potentially useful as disease biomarkers for this plant/pathogen pair. The proposed methodology can be considered as highly reliable, since the diagnosis is based on the whole chromatographic profile rather than in the detection of a single analyte.

Estudos biológicos de espécies de Puccinia utilizando "Germinatélios" / Biological studies of puccina species using "Germinatelia"

Apesar da importância dos fitopatógenos pertencentes à Ordem Pucciniales (=Uredinales), popularmente denominados de ferrugens, certas particularidades de sua biologia são pouco conhecidas, principalmente devido à dificuldade de cultivá-los em meios de cultura e também pela falta de metodologias adequadas ao desenvolvimento das pesquisas. Portanto, o objetivo deste trabalho foi verificar a eficiência de aparatos denominados "germinatélios" para a obtenção de dados sobre a produção de basidiósporos e biologia de diferentes espécies de Pucciniales. Foram utilizadas no estudo as espécies Puccinia psidii, P. pampeana, P. pelargonii-zonalis, P. arachidis, P. mogiphanis, P. emiliae, P. hetereospora, P. malvacearum e P. cnici oleracei. A utilização dos "germinatélios" permitiu constatar elevada produção de basidiósporos (estruturas infectivas) por um período de até 5 meses, à temperaturas entre 12 a 21oC. Além disso, em P. malvacearum foi possível registrar a germinação por repetição (estratégia de sobrevivência) em 4,5% dos basidiósporos produzidos. Todas as espécies foram favorecidas a temperaturas amenas. Estes resultados demonstram, portanto, que a utilização dos "germinatélios" é eficiente, auxiliando na obtenção de dados sobre a biologia e ciclos de diferentes espécies de Puccinia, possibilitando melhor conhecimento sobre estes fitopatógenos, resultando em medidas de manejo e controle mais adequadas/precisas.

Despite the importance of plant pathogens belonging to the Order Pucciniales (=Uredinales), popularly called rusts, certain peculiarities of its biology is poorly known, mainly due to the difficulty of growing them in culture media and also by the lack of appropriate methodologies for the development of research. Therefore, this study was to verify the efficiency of apparatus called "germinatelia" to obtain data about the basidiospores production biology of different Pucciniales species. Were used in the study Puccinia pampeana, P. psidii, P. pelargonii-zonalis, P. arachidis, P. mogiphanis, P. emiliae, P. hetereospora, P. malvacearum and P. cnici-oleracei. The use of "germinatelia" have revealed high basidiospores production for a period up to 5 months at temperatures between 12o and 21oC. Furthermore, in P. malvacearum was possible to record the germination by repetition (survival strategy) in 4.5% of basidiospores produced. All species were favored to mild temperatures. These results therefore demonstrate that the use of "germinatélios" is efficient, assisting in obtaining data about the biology and cycles of different Puccinia species, enabling better understanding of these pathogens, resulting in management and control measures most appropriate/accurate.