Evaluation of three strategies to obtain viruses resistant Pelargonium transformed plants

International audienc

Evaluation of the protection against Xanthomonas in transgenic Pelargomium containing a chimaeric cecropin gene

International audienc

Image analysis and polyphenol profiling unveil red-flesh apple phenotype complexity

Abstract Background The genetic basis of colour development in red-flesh apples (Malus domestica Borkh) has been widely characterised; however, current models do not explain the observed variations in red pigmentation intensity and distribution. Available methods to evaluate the red-flesh trait rely on the estimation of an average overall colour using a discrete class notation index. However, colour variations among red-flesh cultivars are continuous while development of red colour is non-homogeneous and genotype-dependent. A robust estimation of red-flesh colour intensity and distribution is essential to fully capture the diversity among genotypes and provide a basis to enable identification of loci influencing the red-flesh trait. Results In this study, we developed a multivariable approach to evaluate the red-flesh trait in apple. This method was implemented to study the phenotypic diversity in a segregating hybrid F1 family (91 genotypes). We developed a Python pipeline based on image and colour analysis to quantitatively dissect the red-flesh pigmentation from RGB (Red Green Blue) images and compared the efficiency of RGB and CIEL*a*b* colour spaces in discriminating genotypes previously classified with a visual notation. Chemical destructive methods, including targeted-metabolite analysis using ultra-high performance liquid chromatography with ultraviolet detection (UPLC-UV), were performed to quantify major phenolic compounds in fruits’ flesh, as well as pH and water contents. Multivariate analyses were performed to study covariations of biochemical factors in relation to colour expression in CIEL*a*b* colour space. Our results indicate that anthocyanin, flavonol and flavanol concentrations, as well as pH, are closely related to flesh pigmentation in apple. Conclustion Extraction of colour descriptors combined to chemical analyses helped in discriminating genotypes in relation to their flesh colour. These results suggest that the red-flesh trait in apple is a complex trait associated with several biochemical factors

Pre-harvest climate and post-harvest acclimation to cold prevent from superficial scald development in Granny smith apples

International audienceSuperficial scald is one of the most serious postharvest physiological disorders that may affect apples after a prolonged cold storage period. As little is known about its early determinism, we investigated the impact of pre- and post-harvest climatic variations on its incidence on a susceptible apple cultivar. Fruit batches with contrasted phenotype for superficial scald incidence were identified among several years of “Granny Smith” fruit production. The “low scald” year pre-harvest climate was characterised by a warm period followed by a sudden decrease in temperature, playing the part of an in vivo acclimation to cold storage. In agreement, a transcriptomic analysis at harvest revealed that many abiotic stress responsive genes were differentially expressed in fruit peel. In particular 48 Heat Shock Proteins (HSPs) and 5 Heat Shock transcription Factors (HSFs) were strongly induced at harvest when scald incidence was low after 4 months of cold storage. For “high scald” year, a post-harvest cold acclimation of 1 week was efficient to reduce scald incidence. Expression profiles of stress related genes were affected by the acclimation treatment and indicate fruit physiological adaptations to cold storage. The identified stress-responsive genes and in particular HSPs could be useful indicators of the fruit physiological status in order to predict the risk of scald occurrence as early as harvest