Quantification of biotic stresses on aerial parts of plants using Chlorophyll Fluorescence Imaging and Image Analysis

Image analysis is increasingly used in plant phenotyping. Among the various imaging techniques available for plant phenotyping, Chlorophyll Fluorescence Imaging is particularly su itable for the imaging of biotic and abiotic stresses on the aerial parts of plants. Numerous chlorophyll fluorescence parameters may be measured or calculated, but only some of them may provide useful contrasts for the quantification of a given stress on leaves. In the perspective of high throughput phenotyping of biotic stresses on plants, we developed automated procedures to identify Chlorophyll Fluorescence parameters of interest for the quantification of a given biotic stress on large image datasets. The outputs of the automated procedures enable: - the visualization of the whole dataset, by providing contact sheets for each of the chlorophyll fluorescence parameter tested. - the visualization of basic statistics : radial - plot, box - plot and Mann - Whitney tests based on the mean intensity of each parameters are provided to compare the various treatments performed. - images are clustered based on histograms associated to each images, thereby enabling the clustering of images leaves displaying leaves of si milar phytosanitary status. - the objective quantification of disease incidence on each leaf tested. The quantification can discriminate varois stages of symptom development such as necrotic tissues, wilted and chlorotic tissues, and impacted tissues that do not display any symptoms visible to the eye.

Ocorrência de Vibrio parahaemolyticus em mexilhões (Perna perna, Linnaeus, 1758) de banco natural do litoral do município de Palhoça, Santa Catarina, Brasil Occurrence of Vibrio parahaemolyticus in mussels (Perna perna, Linnaeus, 1758) from a natural coastal bed in the municipality of Palhoça, Santa Catarina, Brazil

Foi estudada a ocorrência de Vibrio parahaemolyticus em quarenta amostras de mexilhões (Perna perna, Linnaeus, 1758) procedentes de banco natural da praia da Pinheira, município de Palhoça, Santa catarina, durante um período de três meses. Na metodologia de isolamento foi utilizada a técnica do Número Mais Provável (NMP) com enriquecimento em água alcalina peptonada e subseqüente plaqueamento em ágar TCBS (thiosulfate citrate bile salts sucrose). Em 52,5% das amostras de mexilhões foi constatada a presença de Vibrio parahaemolyticus, com níveis de contaminação entre <3 e 93 NMP/g. Na caracterização sorológica de 61 culturas, 36,1% não permitiram a identificação das estruturas antigênicas O e K; 54,1% somente da estrutura K e apenas 8,2% tiveram ambas as estruturas definidas. Nenhuma dessas culturas apresentou positividade para o teste de Kanagawa.<br>A study was carried out on the occurrence of Vibrio parahaemolyticus in forty samples of mussels (Perna perna, Linnaeus, 1758) from a natural bed at Pinheira Beach, Municipality of Palhoça, Santa Catarina (Brazil), during a three-month period. The most probable number technique was used for isolation methodology with prior enrichment of samples in alkaline peptone water and subsequent planting on thiosulfate citrate bile salts sucrose agar. Vibrio parahaemolyticus was found in 52.5% of samples of mussels with a most probable number range of < 3 to 93 organisms/g. Serotyping was performed on 61 isolates and our findings indicate that 36.1% of these isolates were serologically non-typable; 54.1% of isolates displayed only flagellate antigenic structures and 8.2% had both antigenic structures. None of the isolates were Kanagawa positive