Biology subjects

Gambetta, G. A.

Publications and source records attributed to Gambetta, G. A..

5 recordsLinked to original sources

bioRxiv2024

Nitrogen nutrition impacts grapevine esca leaf symptom incidence, physiology and metabolism.

Nitrogen plays a crucial role in plant growth and defence mechanisms, yet its role in plant-pathogen interactions is complex and remains largely unexplored, especially in perennial crops. This study aimed to investigate the effects of controlled nitrogen nutrition levels on disease incidence, fungal communities, and plant physiology and metabolism. Esca is a widespread grapevine vascular disease affecting physiology, xylem integrity and metabolism. Naturally infected Vitis vinifera L. cv. Sauvignon blanc were subjected to three ammonium nitrate treatments across three seasons, resulting in reduced esca incidence under nitrogen deficiency compared with medium nutrition levels, while excess nitrogen had no significant impact. Nitrogen treatments significantly impacted vine physiology and leaf metabolites but did not affect fungal wood communities. Nitrogen deficiency significantly reduced stem diameter, photosynthesis, and leaf area, likely decreasing whole-plant transpiration, while excess nitrogen increased these factors suggesting a key role of plant transpiration in esca incidence. Additionally, nitrogen deficiency led to significantly higher production of phenylpropanoids, particularly flavonoids, in leaf metabolomes compared to the medium level. These findings highlight the pivotal role of nitrogen in the development of esca through alterations in vine morphology, physiology and metabolism. Fertilization practices may be crucial in the management of plant diseases.

plant biology↗

bioRxiv2024

Grape ripening speed slowed down using natural variation

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. Despite this, the genetic control of ripening is largely unknown. Here, we report a major quantitative trait locus that controls ripening speed, expressed as speed of sugar accumulation. A haplotype originating from the species Vitis riparia halves maximum speed regardless of crop levels and berry sizes. The sequence of events that are normally completed at the onset of ripening in a two-week period known in viticulture as veraison are taking place at a slower speed, thereby attaining ripeness under milder weather conditions in late summer. V. vinifera cultivars show limited phenotypic variation for ripening speed and no selective sweep in the causal genomic region that could derive from domestication or improvement. Closely related species make up for the lack of standing variation, supplying major effect alleles for adapting grape cultivars to climate change. HIGHLIGHT / SIGNIFICANCE STATEMENTReducing the speed of fruit ripening genetically is a means for adapting the grape berry developmental program to the changing needs of the wine industry and in response to global warming. We identified a haplotype in a wild grape species that slows down the speed of ripening in progenies of Vitis vinifera by limiting the speed of sugar accumulation throughout the duration of ripening, a condition of great importance for winemakers to harvest their grapes at the desired level of technological ripeness.

plant biology↗

bioRxiv2020

Seasonal and long-term consequences of esca on grapevine stem xylem integrity

Hydraulic failure has been extensively studied during drought-induced plant dieback, but its role in plant-pathogen interactions is under debate. During esca, a grapevine (Vitis vinifera) disease, symptomatic leaves are prone to irreversible hydraulic dysfunctions but little is known about the hydraulic integrity of perennial organs over the short- and long-term. We investigated the effects of esca on stem hydraulic integrity in naturally infected plants within a single season and across season(s). We coupled direct (ks) and indirect (kth) hydraulic conductivity measurements, and tylose and vascular pathogen detection with in vivo X-ray microtomography visualizations. We found xylem occlusions (tyloses), and subsequent loss of stem ks, in all of the shoots with severe symptoms (apoplexy) and in more than 60% of the shoots with moderate symptoms (tiger-stripe), and no tyloses in shoots that were currently asymptomatic. In vivo stem observations demonstrated that tyloses were observed only when leaf symptoms appeared, and resulted in more than 50% PLC in 40% of symptomatic stems, unrelated to symptom age. The impact of esca on xylem integrity was only seasonal and no long-term impact of disease history was recorded. Our study demonstrated how and to what extent a vascular disease such as esca, affecting xylem integrity, could amplify plant mortality by hydraulic failure. HighlightOur study reveals that esca can critically affect xylem water movement in grapevine perennial organs, by the presence of plant-derived tyloses.

plant biology↗

bioRxiv2020

VviMYB41 orthologs contribute to the water deficit induced suberization of grapevine fine roots

The permeability of roots to water and nutrients is controlled through a variety of mechanisms and one of the most conspicuous is the presence of structures such as the Casparian strips and suberin lamellae. Roots actively regulate the creation of these structures developmentally, along the length of the root, and in response to the environment, including abiotic stresses such as drought. In the current study, we characterized the suberin composition along the length of grapevine fine roots during development and in response to water deficit. In parallel samples we quantified changes in expression of suberin biosynthesis- and deposition-related gene families (via RNAseq) allowing the identification of drought-responsive suberin-related genes. Grapevine suberin composition did not differ between primary and lateral roots, and was similar to that of other species. Under water deficit there was a global upregulation of suberin biosynthesis which resulted in an increase of suberin specific monomers, but without changes in their relative abundances, and this upregulation took place across all the developmental stages of fine roots. These changes corresponded to the upregulation of numerous suberin biosynthesis- and deposition-related genes which included orthologs of the previously characterized AtMYB41 transcriptional factor. Functional validation of two grapevine MYB41 orthologs, VviMYB41 and VviMYB41-like, confirmed their ability to globally upregulate suberin biosynthesis and deposition. This study provides a detailed characterization of the developmental and water deficit induced suberization of grapevine fine roots and identifies important orthologs responsible for suberin biosynthesis, deposition, and its regulation in grape. One sentence summaryOur study details the biochemical changes and molecular regulation of how grapevines decrease their root permeability during drought.

plant biology↗

bioRxiv2019

Minimally invasive, pressure probe based sampling allows for in-situ gene expression analyses in plant cells.

BackgroundGene expression analyses are conducted using multiple approaches and increasingly research has been focused on assessing gene expression at the level of a tissue or even single-cells. To date, methods to assess gene expression at the single-cell in plant tissues have been semi-quantitative, require tissue disruption, and/or involve laborious, possibly artifact-inducing manipulation. In this work, we used grape berries (Vitis vinifera L. Zinfandel) as a model in order to examine the validity and reproducibility of an in-situ gene expression analysis method combining a cell pressure probe (CPP) with quantitative PCR (qPCR).\n\nResultsWe developed a method to directly assess gene expression levels via qPCR from cellular fluids sampled in-situ with a CPP. Cellular fluids, with volumes in the picoliter range, were collected from intact berries with a CPP at various depths across skin and mesocarp tissues. The expression of a key anthocyanin biosynthetic gene, UDP-glucose: flavonoid 3-O-glucosyltransferase (VviUFGT), was analyzed as a test case since its expression is restricted to cells producing anthocyanins in grape berry skins during ripening. The method identifies samples contaminated with significant levels of genomic DNA by amplifying a region of VviUFGT that spans an intron. Therefore false positives were discarded which occurred in 28% of the samples tested. Shallow probing of skin cells showed high VviUFGT expression as expected while deeper probing of mesocarp cells resulted in no VviUFGT expression.\n\nConclusionsThe clear correspondence of VviUFGT expression to the targeted cell samples suggests that the in-situ gene expression analysis using a CPP is reliable and does not result in contamination as the probe moves through tissues. This method can be paired to single-cell transcriptomic analyses in the future. We conclude that this technique represents a minimally invasive method of sampling plant cells in-situ which creates an opportunity for the analysis of cellular level, spatiotemporal responses in heterogeneous plant tissues.

plant biology↗