GiESCO 2019 banner
IVES 9 IVES Conference Series 9 GiESCO 9 GiESCO 2019 9 Optical visualization of embolism spread in drought‐induced leaves: revealing differences across three grapevine genotypes

Optical visualization of embolism spread in drought‐induced leaves: revealing differences across three grapevine genotypes

Abstract

Context and purpose of the study ‐Evaluation of xylem embolism is an important challenge in identifying drought tolerant genotypes within the context of climate change. Visualization methods such as the optical vulnerability technique (Brodribb et al. 2016) has been shown to be a reliable and accessible approach to observe the spread of embolism in dehydrating leaves (Hochberg et al. 2017; Lamarque et al. 2018). In this study we use the optical technique to examine the development of leaf embolism in three grapevine cultivars as a method to characterize their drought‐tolerance strategy.

Material and methods ‐Potted plants of Grenache, Semillon and Syrah were grown outdoors in 2018 under well‐watered conditions. Leaf embolism formation and spread was evaluated in four individuals per genotype by monitoring changes in light transmission through the xylem after the irrigation was cutted‐off. For each plant, a mature leaf was placed on a scanner and imaged every 5 minutes until complete desiccation. Simultaneous measurements of stem water potential (Ystem) were registered using psychrometers properly installed on the main stem. The accuracy of the psychrometers was evaluated by measuring the leaf water potential in adjacent leaves previously bagged with aluminum foil using a Scholander pressure bomb. The stack of images obtained were analyzed using the ImageJ software as described in Lamarque et al. (2018). The percentage of embolism (%emb) was calculated as the cumulative number of embolised pixels normalized to the total number of embolised pixels throughout the dehydration. Finally, the %emb was represented as a function of Ystem and different events were colored using a continuous scale respective to their time of appearance.

Results ‐Embolism formation and spread in the leaves were detected at different times for each cultivar since the beginning of drought. While Grenache showed the first embolism event at around 48 h of desiccation (‐0.48 MPa), Semillon showed its first event after 72 h (‐1.5 MPa). Syrah plants were placed in between the other two genotypes showing the first embolisms at ‐0.68 MPa. The vulnerability curves (%emb vs Ystem) constructed from the data obtained followed a sigmoidal function for all genotypes and showed a great variability between individuals. In spite of this, the time and water potentials at which the main embolisms occurred was significantly different between cultivars where Grenache showed an early cavitation (P50 at ‐1.43 MPa), followed by Syrah (P50 at ‐1.65 MPa) and Semillon (P50 at ‐2.08 Mpa). The optical technique tested in this study revealed genotype differences in the temporal appearance of leaf embolism suggesting a different strategy to tolerate dehydration. 

DOI:

Publication date: June 19, 2020

Issue: GiESCO 2019

Type: Article

Authors

Silvina DAYER (1), Régis BURLETT (2), Laurent LAMARQUE2, Sylvain DELZON2, Gregory GAMBETTA1*

(1) Institut des Sciences de la Vigne et du Vin, Écophysiologie et Génomique Fonctionnelle de la Vigne, UMR 1287, 210 Chemin de Leysotte, F-33140 Villenave-d’Ornon, France
(2) Biodiversité Gènes et Communautés, Institut National de la Recherche Agronomique (INRA), Université Bordeaux, 33610 Cestas, France

Contact the author

Keywords

 Embolism, drought, xylem cavitation, vessels, grapevine

Tags

GiESCO 2019 | IVES Conference Series

Citation

Related articles…

The impacts of frozen material-other-than-grapes (MOG) on aroma compounds of red wine varieties

An undesirable note called “floral taint” has been observed in red wines by winemakers in the Niagara region caused by large volumes of frozen leaves and petioles [materials-other-than-grapes (MOG)] introduced during mechanical harvest and subsequent winemaking late in the season. The volatiles, which we hypothesized are responsible, are primarily terpenes, norisoprenoids, and specific esters in frozen leaves and petioles. The purpose of this study was to investigate the volatile compounds which may cause the floral taint problem and explore how much of them (thresholds) may lead to the problem. Also, the glycosidic precursors of some of these compounds were analyzed to see the changes happening during frost events.

Aromatic profile of six different clones of Chardonnay grape berries in Minas Gerais (Brazil)

Aromas are one of the key points in food analysis since they are related to character, quality and consequently consumer acceptance. It is not different in the winery industry, where the aromatic profile is a combination of viticultural and oenological practices. Based on the development of more aromatic clones and on the potential to produce sparkling wines at Caldas, in the southern region of Minas Gerais (Brazil) (21°55´S and 46°23´W, altitude 1,100m), the aim of this work was the determination of volatile compounds in six different clones of Chardonnay grape berries to better understand which compounds add bouquet to the wine, and additionally comprehend the impacts of the edaphoclimatic and annual conditions on the improvement of grape-growing and winemaking practices.

Improving stilbenes in vitis Labrusca L. Grapes through methyl jasmonate applications

Grapes (Vitis sp.) are considered a major source of phenolic compounds such as flavonols, anthocyanins and stilbenes. Studies related to the beneficial effects of these compounds on health have encouraged research aimed at increasing their concentration in fruits. On this behalf, several plant growth regulators such as jasmonic acid and its volatile ester, methyl-jasmonate (MeJa), have demonstrated promising results in many fruits. However, Brazilian subtropical climate might interfere on treatment response. The present study aims to evaluate the application of MeJa in the pre-harvest period in Concord and Isabel Precoce grapes (Vitis labrusca L.).

Service crop effects on grapevine water and nitrogen status and yield under Mediterranean climate

Service crops in vineyard can provide multiple ecosystem services but they can also lead to competition with the grapevine for soil resources in the Mediterranean region due to potential severe droughts (Garcia et al., 2018). One of the levers of action to manage this competition is the choice of species adapted in terms of growth dynamics and water and nutrients’ needs. The objectives of this study were to determine the effect of temporary service crops on grapevine water and nitrogen status and grapevine yield and yield components in a Mediterranean vineyard.

Impact of deficit irrigation strategies on terpene concentration in Gewürztraminer grapes

Deficit irrigation is a viticultural practice often applied to improve the phenolic composition of red grapes and wines. However, the impact of this practice on grape terpenes – key aromatics for several grapes and wines – remains largely unknown. This study investigated the impact of deficit irrigation strategies on free and glycosylated terpenes in Gewürztraminer grapes. In a field study conducted in Oliver, BC, in 2016, 2017, and 2018, deficit irrigation regimes were applied to Gewürztraminer vines at different developmental stages (pre-veraison = Early Deficit, ED; post-veraison = Late Deficit, LD; throughout the season = Prolonged Deficit, PD). A well-irrigated control (CN) treatment was also established.