Grapevine yellows: Comparison of different procedures for DNA extraction and amplification with PCR for routine diagnosis of phytoplasmas in grapevine

In order to devise a procedure to be used as reference for detection of grapevine phytoplasmas and monitoring of Flavescence dorée, 12 combinations comprising three methods of plant DNA extraction and 4 procedures for amplification in polymerase chain reaction of phytoplasma DNA were examined in parallel using the same plant tissues infected with phytoplasmas. In a first series tissues of periwinkles (Catharanthus roseus) infected with phytoplasma isolates of the Elm yellows group (16SrV) and maintained in the greenhouse, were used. In a second series tissues of grapevines (Vitis vinifera) naturally infected with Flavescence dorée or Palatinate grapevine yellows phytoplasma were used. The DNA preparations obtained with each of the three extraction procedures were used undiluted or serially diluted, as target DNA in the 4 nested-polymerase chain reactions. The results showed differences in the efficiency among different methods of extraction as well as in the sensitivity among the DNA amplification procedures, which improved when DNA extracted from field grapevines was diluted. After additional comparative validation on numerous field-collected samples of GY-affected grapevines, the quickest extraction procedure was selected for use in routine diagnosis, with nested-PCR amplification either of ribosomal DNA or of the FD9 DNA fragment specific for Flavescence dorée and other 16SrV group phytoplasmas

Identification of the hygrothermal properties of a building envelope material by the Covariance Matrix Adaptation evolution strategy

International audienceThis paper proposes the application of the Covariance Matrix Adaptation (CMA) evolution strategy for the identification of building envelope materials hygrothermal properties. All material properties are estimated on the basis of local temperature and relative humidity measurements, by solving the inverse heat and moisture transfer problem. The applicability of the identification procedure is demonstrated in two stages: first, a numerical benchmark is developed and used as to show the potential identification accuracy, justify the choice for a Tikhonov reg-ularisation term in the fitness evaluation, and propose a method for its appropriate tuning. Then, the procedure is applied on the basis of experimental measurements from an instrumented test cell, and compared to the experimental characterisation of the observed material. Results show that an accurate estimation of all hygrothermal properties of a building material is feasible, if the objective function of the inverse problem is carefully defined