Grape ripening speed slowed down using natural variation.

Reducing the speed of ripening genetically is a means for adapting grape berry development to the changing needs of the wine industry and in response to global warming. Understanding ripening patterns and governing ripening speed are central aspects of grapevine (Vitis vinifera) berry biology owing to the importance of grape ripeness in winemaking. Given this reality, it is surprising that the genetic control of ripening remains unknown.

Xylem network connectivity and embolism spread in grapevine(Vitis vinifera L.).

Xylem networks are vulnerable to the formation and spread of gas embolisms that reduce water transport. Embolisms spread through interconduit pits, but the three-dimensional (3D) complexity and scale of xylem networks means that the functional implications of intervessel connections are not well understood. Here, xylem networks of grapevine (Vitis vinifera L.

A continuum of stomatal responses to water deficits among 17 wine grape cultivars (Vitis vinifera).

Vitis vinifera L. cultivars have been previously classified as isohydric, near-isohydric, anisohydric or isohydrodynamic, depending on the study. To test the hypothesis that V.

The Xylella fastidosa RTX operons: evidence for the evolution of protein mosaics through novel genetic exchanges.

Background: Xylella fastidiosa (Xf) is a gram negative bacterium inhabiting the plant vascular system. In most species this bacterium lives as a benign symbiote, but in several agriculturally important plants (e.g.

Characterization of major ripening events during softening in grape: turgor, sugar accumulation, abscisic acid metabolism, colour development, and their relationship with growth.

Along with sugar accumulation and colour development, softening is an important physiological change during the onset of ripening in fruits. In this work, we investigated the relationships among major events during softening in grape (Vitis vinifera L.) by quantifying elasticity in individual berries.

Unravelling the geometry of data matrices: effects of water stress regimes on winemaking.

A new method is proposed for unravelling the patterns between a set of experiments and the features that characterize those experiments. The aims are to extract these patterns in the form of a coupling between the rows and columns of the corresponding data matrix and to use this geometry as a support for model testing. These aims are reached through two key steps, namely application of an iterative geometric approach to couple the metric spaces associated with the rows and columns, and use of statistical physics to generate matrices that mimic the original data while maintaining their inherent structure, thereby providing the basis for hypothesis testing and statistical inference.

Water Transport Properties of the Grape Pedicel during Fruit Development: Insights into Xylem Anatomy and Function Using Microtomography.

Xylem flow of water into fruits declines during fruit development, and the literature indicates a corresponding increase in hydraulic resistance in the pedicel. However, it is unknown how pedicel hydraulics change developmentally in relation to xylem anatomy and function. In this study on grape (Vitis vinifera), we determined pedicel hydraulic conductivity (kh) from pressure-flow relationships using hydrostatic and osmotic forces and investigated xylem anatomy and function using fluorescent light microscopy and x-ray computed microtomography.

Polarity of water transport across epidermal cell membranes in Tradescantia virginiana.

Using the automated cell pressure probe, small and highly reproducible hydrostatic pressure clamp (PC) and pressure relaxation (PR) tests (typically, applied step change in pressure = 0.02 MPa and overall change in volume = 30 pL, respectively) were applied to individual Tradescantia virginiana epidermal cells to determine both exosmotic and endosmotic hydraulic conductivity (L(p)(OUT) and L(p)(IN), respectively). Within-cell reproducibility of measured hydraulic parameters depended on the method used, with the PR method giving a lower average coefficient of variation (15.

Water uptake along the length of grapevine fine roots: developmental anatomy, tissue-specific aquaporin expression, and pathways of water transport.

To better understand water uptake patterns in root systems of woody perennial crops, we detailed the developmental anatomy and hydraulic physiology along the length of grapevine (Vitis berlandieri × Vitis rupestris) fine roots from the tip to secondary growth zones. Our characterization included the localization of suberized structures and aquaporin gene expression and the determination of hydraulic conductivity (Lpr) and aquaporin protein activity (via chemical inhibition) in different root zones under both osmotic and hydrostatic pressure gradients. Tissue-specific messenger RNA levels of the plasma membrane aquaporin isogenes (VvPIPs) were quantified using laser-capture microdissection and quantitative polymerase chain reaction.

Analysis of HRCT-derived xylem network reveals reverse flow in some vessels.

Long distance water and nutrient transport in plants is dependent on the proper functioning of xylem networks, a series of interconnected pipe-like cells that are vulnerable to hydraulic dysfunction as a result of drought-induced embolism and/or xylem-dwelling pathogens. Here, flow in xylem vessels was modeled to determine the role of vessel connectivity by using three dimensional xylem networks derived from High Resolution Computed Tomography (HRCT) images of grapevine (Vitis vinifera cv. 'Chardonnay') stems.

In vivo visualizations of drought-induced embolism spread in Vitis vinifera.

Long-distance water transport through plant xylem is vulnerable to hydraulic dysfunction during periods of increased tension on the xylem sap, often coinciding with drought. While the effects of local and systemic embolism on plant water transport and physiology are well documented, the spatial patterns of embolism formation and spread are not well understood. Using a recently developed nondestructive diagnostic imaging tool, high-resolution x-ray computed tomography, we documented the dynamics of drought-induced embolism in grapevine (Vitis vinifera) plants in vivo, producing the first three-dimensional, high-resolution, time-lapse observations of embolism spread.

Xylem vessel relays contribute to radial connectivity in grapevine stems (Vitis vinifera and V. arizonica; Vitaceae).

Premise Of The Study: Xylem network connections play an important role in water and nutrient transport in plants, but also facilitate the spread of air embolisms and xylem-dwelling pathogens. This study describes the structure and function of vessel relays found in grapevine xylem that form radial and tangential connections between spatially discrete vessels.

Methods: We used high-resolution computed tomography, light microscopy, scanning electron microscopy, and single-vessel dye injections to characterize vessel relays in stems and compare their distributions and structure in two Vitis species.

Genomic DNA-based absolute quantification of gene expression in Vitis.

Many studies in which gene expression is quantified by polymerase chain reaction represent the expression of a gene of interest (GOI) relative to that of a reference gene (RG). Relative expression is founded on the assumptions that RG expression is stable across samples, treatments, organs, etc., and that reaction efficiencies of the GOI and RG are equal; assumptions which are often faulty.

Impact of diurnal temperature variation on grape berry development, proanthocyanidin accumulation, and the expression of flavonoid pathway genes.

Little is known about the impact of temperature on proanthocyanidin (PA) accumulation in grape skins, despite its significance in berry composition and wine quality. Field-grown grapes (cv. Merlot) were cooled during the day or heated at night by +/-8 °C, from fruit set to véraison in three seasons, to determine the effect of temperature on PA accumulation.

Fruit ripening in Vitis vinifera: light intensity before and not during ripening determines the concentration of 2-methoxy-3-isobutylpyrazine in Cabernet Sauvignon berries.

The roles of light and temperature in the accumulation of the vegetal impact compound 2-methoxy-3-isobutylpyrazine (MIBP) in grape (Vitis vinifera L.) berries were determined. Individual clusters were exposed to various light intensities using neutral density shade cloth before ripening, during ripening or throughout the season in three growing seasons.

Fruit ripening in Vitis vinifera: spatiotemporal relationships among turgor, sugar accumulation, and anthocyanin biosynthesis.

This study reports the first observations indicating the spatiotemporal relationships among genetic and physiological aspects of ripening in the berry of Vitis vinifera. At the onset of ripening in the red flesh variety Alicante Bouschet, colour development began in the flesh at the stylar end of the fruit and progressed toward the pedicel end flesh and into the skin. Tissue solute potential and cell turgor also decreased first in the flesh.

Automated analysis of three-dimensional xylem networks using high-resolution computed tomography.

Connections between xylem vessels represent important links in the vascular network, but the complexity of three-dimensional (3D) organization has been difficult to access. This study describes the development of a custom software package called TANAX (Tomography-derived Automated Network Analysis of Xylem) that automatically extracts vessel dimensions and the distribution of intervessel connections from high-resolution computed tomography scans of grapevine (Vitis vinifera) stems, although the method could be applied to other species. Manual and automated analyses of vessel networks yielded similar results, with the automated method generating orders of magnitude more data in a fraction of the time.

Xylem structure of four grape varieties and 12 alternative hosts to the xylem-limited bacterium Xylella fastidious.

Background And Aims: The bacterium Xylella fastidiosa (Xf), responsible for Pierce's disease (PD) of grapevine, colonizes the xylem conduits of vines, ultimately killing the plant. However, Vitis vinifera grapevine varieties differ in their susceptibility to Xf and numerous other plant species tolerate Xf populations without showing symptoms. The aim of this study was to examine the xylem structure of grapevines with different susceptibilities to Xf infection, as well as the xylem structure of non-grape plant species that support or limit movement of Xf to determine if anatomical differences might explain some of the differences in susceptibility to Xf.

2-Methoxy-3-isobutylpyrazine in grape berries and its dependence on genotype.

2-Methoxy-3-isobutylpyrazine (MIBP) contributes a bell pepper aroma to many grape cultivars and has a reported aroma threshold of ∼2 ng L(-1) in water. The purpose of this study was twofold: (1) develop a procedure using headspace solid phase micro-extraction combined with GC-MS in the selected ion monitoring mode (HS-SPME-GC-MS-SIM) for analysis of MIBP in grape berries, and (2) determine the location of MIBP biosynthesis in grapevines by approach grafting clusters of Vitis vinifera L. cvs Cabernet Sauvignon and Muscat blanc onto each other.

The dynamics of embolism repair in xylem: in vivo visualizations using high-resolution computed tomography.

Water moves through plants under tension and in a thermodynamically metastable state, leaving the nonliving vessels that transport this water vulnerable to blockage by gas embolisms. Failure to reestablish flow in embolized vessels can lead to systemic loss of hydraulic conductivity and ultimately death. Most plants have developed a mechanism to restore vessel functionality by refilling embolized vessels, but the details of this process in vessel networks under tension have remained unclear for decades.

Measurement of vulnerability to water stress-induced cavitation in grapevine: a comparison of four techniques applied to a long-vesseled species.

Among woody plants, grapevines are often described as highly vulnerable to water-stress induced cavitation with emboli forming at slight tensions. However, we found native embolism never exceeded 30% despite low xylem water potentials (Psi(x)) for stems of field grown vines. The discrepancy between native embolism measurements and those of previous reports led us to assess vulnerability curve generation using four separate methods and alterations (i.

Sugar and abscisic acid signaling orthologs are activated at the onset of ripening in grape.

The onset of ripening involves changes in sugar metabolism, softening, and color development. Most understanding of this process arises from work in climacteric fruits where the control of ripening is predominately by ethylene. However, many fruits such as grape are nonclimacteric, where the onset of ripening results from the integration of multiple hormone signals including sugars and abscisic acid (ABA).

Vascular function in grape berries across development and its relevance to apparent hydraulic isolation.

During the latter stages of development in fleshy fruit, water flow through the xylem declines markedly and the requirements of transpiration and further expansion are fulfilled primarily by the phloem. We evaluated the hypothesis that cessation of water transport through the xylem results from disruption or occlusion of pedicel and berry xylem conduits (hydraulic isolation). Xylem hydraulic resistance (R(h)) was measured in developing fruit of grape (Vitis vinifera 'Chardonnay') 20 to 100 d after anthesis (DAA) and compared with observations of xylem anatomy by light and cryo-scanning electron microscopy and expression of six plasma membrane intrinsic protein (PIP) aquaporin genes (VvPIP1;1, VvPIP1;2, VvPIP1;3, VvPIP2;1, VvPIP2;2, VvPIP2;3).

The effects of Pierce's disease on leaf and petiole hydraulic conductance in Vitis vinifera cv. Chardonnay.

In this study, we test the hypothesis that the symptoms of Pierce's Disease (PD) result from the occlusion of xylem conduits by the bacteria Xylella fastidiosa (Xf ). Four treatments were imposed on greenhouse-grown Vitis vinifera cv. Chardonnay: well-watered and deficit-irrigated plants with and without petiole inoculation with Xf.

Seasonal pattern of apoplastic solute accumulation and loss of cell turgor during ripening of Vitis vinifera fruit under field conditions.

Using a novel pressure membrane (PM) apparatus for the extraction of apoplastic fluid from field-grown grape (Vitis vinifera L.) berries, our hypothesis that significant apoplast solutes accumulate at the beginning of the ripening process (i.e.