The rate of ethylene biosynthesis was monitored throughout the four stages (S1, S2, S3, and S4) of peach (Prunus persica L. Batsch `Springcrest') fruit development. The highest values of ethylene production were detected during the early S1 and at ripening. During S1, the increase in the evolution of ethylene was accompanied by high activity of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO). A weak accumulation of ACO mRNA was detected in developing fruitlets, indicating that ACO may play a specific role in modulating the rate of ethylene biosynthesis during the early growth stage. When fruitlets harvested at S1 were flushed with propylene (500 mL·L-1) for 48 h, a two-fold increase of ethylene biosynthesis and a dramatic induction of ACO activity were observed. Treatment with the ethylene analogue greatly stimulated the expression of ACO gene(s). During ripening, the climacteric occurred when fruit had softened to ≈20 N. This process was preceded by an increase in ACC content and ACO activity in the mesocarp. ACO transcripts began to accumulate before the rise in whole-fruit ethylene biosynthesis with peak levels coincident with the climacteric when the highest values of ACO activity were detected. Propylene greatly enhanced ACO gene expression and stimulated the ripening-associated ethylene climacteric. ACO-related transcripts also accumulated in fruit treated with nitrogen for 72 hours.

Effective crop improvement, whether through selective breeding or biotech strategies, is largely dependent on the cumulative knowledge of a species’ pangenome and its containing genes. Acquiring this knowledge is specially challenging in grapevine, one of the oldest fruit crops grown worldwide, which is known to have more than 30,000 genes. Well-established research communities studying model organisms have created and maintained, through public and private funds, a diverse range of online tools and databases serving as repositories of genomes and gene function data. The lack of such resources for the non-model, but economically important, Vitis vinifera species has driven the need for a standardised collection of genes within the grapevine community. In an effort led by the Integrape COST Action CA17111, we have recently developed the first grape gene reference catalogue, where genes are ascribed to functional data, including their accession identifiers from different genome-annotation versions (https://integrape.eu/resources/genes-genomes/). We present and discuss this gene repository together with a validation-level scheme based on varied supporting evidence found in current literature. The catalogue structure and online submission form provided permits community curation. Finally, we present the Gene Cards tool, developed within the Vitis Visualization (VitViz) platform, to visualize the data collected in the catalogue and link gene function with tissue-specific expression derived from public transcriptomic data. This perspective article aims to present these resources to the community as well as highlight their potential use, in particular for plant-breeding applications.

No abstract

Berry texture and berry skin mechanical properties are traits with high agronomic relevance because they are related to quality parameters and marketing requirements of wine, table, and raisin grapes. Searching for QTLs linked to berry texture, an F1 population of 152 individuals and their parents were used in this study. These F1 plants were obtained crossing Raboso Veronese, a seeded black wine grape cultivar, and Sultanina, a seedless white grape variety, especially used for raisins. Density flotation was applied for berry sorting improving the management of many and highly variable genotypes, irrespective of the quantification of specific molecule classes. Berries were evaluated for technological ripeness parameters and mechanical properties. Texture parameters were taken as raw data and as data normalised on berry dimensions, i.e., berry diameter or surface or volume. SSR molecular markers were used to produce a genetic map and a major QTL for berry texture was found on chromosome 18 with traits related to berry firmness showing a phenotypical explained variance higher than 60 %, and traits related to berry resilience, springiness and cohesiveness showing a variance higher than 50 %. Surprisingly, this QTL showed to be associated with SSR markers linked to VviAGL11, the main gene linked to seedlessness. VviAGL11 expression and co-expression profiling during grape ripening was evaluated using available information; this data suggested a role for this gene on the texture of a ripe berry.List of Abbreviations:ABW, average berry weightBR, berry resilienceBR_diam, berry resilience normalised on berry diameterBR_sur, berry resilience normalised on berry surfaceBR_vol, berry resilience normalised on berry volumeBS_ratio, berry springinessBS_ratio_diam, berry springiness normalised on berry diameterBS_ratio_sur, berry springiness normalised on berry surfaceBS_ratio_vol, berry springiness normalised on berry volumeBCo, berry cohesivenessBCo_diam, berry cohesiveness normalised on berry diameterBCo_sur, berry cohesiveness normalised on berry surfaceBCo_vol, berry cohesiveness normalised on berry volumeBH, berry hardnessBH_diam, berry hardness normalised on berry diameterBH_sur, berry hardness normalised on berry surfaceBH_vol, berry hardness normalised on berry volumeBG, berry gumminessBG_diam, berry gumminess normalised on berry diameterBG_sur, berry gumminess normalised on berry surfaceBG_vol, berry gumminess normalised on berry volumeBCh_ratio, berry chewinessBCh_ratio_diam, berry chewiness normalised on berry diameterBCh_ratio_sur, berry chewiness normalised on berry surfaceBCh_ratio_vol, berry chewiness normalised on berry volumeFsk, berry skin break forceWsk, berry skin break energyEsk, berry skin resistance to the axial deformationSpsk, berry skin thickness

The partial dehydration of grapes after harvest is a traditional practice in several winegrowing regions that leads to the production of high quality wines. Postharvest dehydration (also known as withering) has a significant impact on the overall metabolism and physiology of the berry, yielding a final product that is richer in sugars, solutes, and aroma compounds. These changes are, at least in part, the result of a stress response, which is controlled at transcriptional level, and are highly dependent on the grape water loss kinetics and the environmental parameters of the facility where grapes are stored to wither. However, it is difficult to separate the effects driven by each single environmental factor from those of the dehydration rate, especially discerning the effect of temperature that greatly affects the water loss kinetics. To define the temperature influence on grape physiology and composition during postharvest dehydration, the withering of the red-skin grape cultivar Corvina (Vitis vinifera) was studied in two conditioned rooms set at distinct temperatures and at varying relative humidity to maintain an equal grape water loss rate. The effect of temperature was also studied by withering the grapes in two unconditioned facilities located in geographic areas with divergent climates. Technological, LC-MS and GC-MS analyses revealed higher levels of organic acids, flavonols, terpenes and cis- and trans-resveratrol in the grapes withered at lower temperature conditions, whereas higher concentrations of oligomeric stilbenes were found in the grapes stored at higher temperatures. Lower expression of the malate dehydrogenase and laccase, while higher expression of the phenylalanine ammonia-lyase, stilbene synthase and terpene synthase genes were detected in the grapes withered at lower temperatures. Our findings provide insights into the importance of the temperature in postharvest withering and its effect on the metabolism of the grapes and on the quality of the derived wines.