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For two successive years, cell walls were isolated from the internal part of skin cells of Vitis vinifera L. cv. Cabernet Sauvignon grape berries grown in a vineyard. Procyanidin localization and composition were determined over the course of development. Tannins were mainly localized in the inner cell fraction, due to their biosynthesis and storage. Cell wall tannins always exhibited a higher mean degree of polymerization as compared to the internal cell fraction, which had a constant mDP. The mDP of cell wall tannins also tended to increase at the end of maturation. Our results suggest tannin polymerization near the cell wall but an aggregation in the vacuole during growth. The tannin composition was typical of skins, and small differences were noted between the two cell parts. Surprisingly, epigallocatechin-3-gallate was also detected, although in a very small amount. Epicatechin was present in significant proportions in both fractions, especially as an extension subunit, while epigallocatechin was likewise abundant, also as a terminal subunit. Last, procyanidin composition and organization seemed to be characteristic of the Cabernet Sauvignon variety.

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Accumulated in large amounts in carrot, carotenoids are an important product quality attribute and therefore a major breeding trait. However, the knowledge of carotenoid accumulation genetic control in this root vegetable is still limited. In order to identify the genetic variants linked to this character, we performed an association mapping study with a candidate gene approach. We developed an original unstructured population with a broad genetic basis to avoid the pitfall of false positive detection due to population stratification. We genotyped 109 SNPs located in 17 candidate genes – mostly carotenoid biosynthesis genes – on 380 individuals, and tested the association with carotenoid contents and color components. Total carotenoids and β-carotene contents were significantly associated with genes zeaxanthin epoxydase (ZEP), phytoene desaturase (PDS) and carotenoid isomerase (CRTISO) while α-carotene was associated with CRTISO and plastid terminal oxidase (PTOX) genes. Color components were associated most significantly with ZEP. Our results suggest the involvement of the couple PDS/PTOX and ZEP in carotenoid accumulation, as the result of the metabolic and catabolic activities respectively. This study brings new insights in the understanding of the carotenoid pathway in non-photosynthetic organs.

<p style="text-align: justify;">Grape berry ripening is characterised by numerous metabolic and physiological changes, placed under hormonal control. The phytohormone abscisic acid (ABA) is considered as a possible promoter of « véraison », since it accumulates at this time. In order to evaluate its impact, we assess the effect of ABA on several parameters of maturity: anthocyanins synthesis, phenylalanine ammonia-lyase activity, sugar contents, acidity and maturity index, both in untreated berry skin and in skin of berries submitted to applications of exogenous ABA. The maturation processes we focused on appear ABA-dependent, as they occured immediately after ABA accumulation in the skin. Treatment also shows a close relationship between ABA and the beginning of ripening. These results allow us to conclude that ABA content could modulate the triggering of « véraison ».</p>

Gene inactivation and complementation experiments showed that the tripartite AheABC efflux pump of Aeromonas hydrophila extruded at least 13 substrates, including nine antibiotics. The use of phenylalaninearginine-␤-naphthylamide (PA␤N) revealed an additional system(s) contributing to intrinsic resistance. This is the first analysis of the role of multidrug efflux systems in Aeromonas spp.

Main conclusion Variations in gene expression can partially explain the difference of carotenoid accumulation in secondary phloem and xylem of fleshy carrot roots. The carrot root is well divided into two different tissues separated by vascular cambium: the secondary phloem and xylem. The equilibrium between these two tissues represents an important issue for carrot quality, but the knowledge about the respective carotenoid accumulation is sparse. The aim of this work was (i) to investigate if variation in carotenoid biosynthesis gene expression could explain differences in carotenoid content in phloem and xylem tissues and (ii) to investigate if this regulation is differentially modulated in the respective tissues by water-restricted growing conditions. In this work, five carrot genotypes contrasting by their root color were studied in control and water-restricted conditions. Carotenoid content and the relative expression of 13 genes along the carotenoid biosynthesis pathway were measured in the respective tissues. Results showed that in orange genotypes and the purple one, carotenoid content was higher in phloem compared to xylem. For the red one, no differences were observed. Moreover, in control condition, variations in gene expression explained the different carotenoid accumulations in both tissues, while in water-restricted condition, no clear association between gene expression pattern and variations in carotenoid content could be detected except in orange-rooted genotypes. This work shows that the structural aspect of carrot root is more important for carotenoid accumulation in relation with gene expression levels than the consequences of expression changes upon water restriction.