Nitrogen nutrition influences some biochemical responses to iron deficiency in tolerant and sensitive genotypes of Vitis

The effects of nitrogen source on iron deficiency responses were investigated in two Vitis genotypes, one tolerant to limestone chlorosis Cabernet Sauvignon (Vitis vinifera cv.) and the other susceptible Gloire de Montpellier (Vitis riparia cv.). Plants were grown with or without Fe(III)-EDTA, and with NO 3 - alone or a mixture of NO 3 - and NH 4 + . Changes in pH of the nutrient solution and root ferric chelate reductase (FC-R) activity were monitored over one week. We carried out quantitative metabolic profiling (1H-NMR) and determined the activity of enzymes involved in organic acid metabolism in root tips. In iron free-solutions, with NO 3 - as the sole nitrogen source, the typical Fe-deficiency response reactions as acidification of the growth medium and enhanced FC-R activity in the roots were observed only in the tolerant genotype. Under the same nutritional conditions, organic acid accumulation (mainly citrate and malate) was found for both genotypes. In the presence of NH4+, the sensitive genotype displayed some decrease in pH of the growth medium and an increase in FC-R activity. For both genotypes, the presence of NH 4 + ions decreased significantly the organic acid content of roots. Both Vitis genotypes were able to take up NH 4 + from the nutrient solution, regardless of their sensitivity to iron deficiency. The presence of N-NH 4 + modified typical Fe stress responses in tolerant and sensitive Vitis genotypes. © 2006 Springer Science+Business Media B.V.This work was partly funded by the Franco-Spanish bilateral cooperation program (Picasso Program HF2003-273) and by Aquitaine-Aragón cooperation programs (Aq23, Aq25). Sergio Jiménez was supported by a I3P fellowship from CSIC/FSE (Consejo Superior de Investigaciones Científicas/Fondo Social Europeo) and a travel fellowship from DGA/CAI (CA 5/03).Peer Reviewe

Acta hortic.

Regulation of root system growth and architecture is an adaptive mechanism evolved by plants to cope with variable nitrogen availability in the soil. In grafted plants, this process depends on intrinsic properties of the rootstock as well as long-distanc

Comment adapter la viticulture de demain?

Présentation orale, Festival Pint of Science 2018, Manifestation (2018-05-14 - 2018-05-16), Bordeaux, FR

How do grapevine rootstocks modify phosphorus concentration in scion ?

National audienc

Scion genotypes exert long distance control over rootstock transcriptome responses to low phosphate in grafted grapevine

Background : Grafting is widely used in horticulture and rootstocks are known to modify scion growth and adaptation to soil conditions. However, the role of scion genotype in regulating rootstock development and functioning has remained largely unexplored. In this study, reciprocal grafts of two grapevine genotypes were produced as well as the corresponding homo-graft controls. These plants were subjected to a low phosphate (LP) treatment and transcriptome profiling by RNA sequencing was done on root samples collected 27 h after the onset of the LP treatment.Results: A set of transcripts responsive to the LP treatment in all scion/rootstock combinations was identified. Gene expression patterns associated with genetic variation in response to LP were identified by comparing the response of the two homo-grafts. In addition, the scion was shown to modify root transcriptome responses to LP in a rootstock dependent manner. A weighted gene co-expression network analysis identified modules of correlated genes; the analysis of the association of these modules with the phosphate treatment, and the scion and rootstock genotype identified potential hub genes.Conclusions: This study provides insights into the response of grafted grapevine to phosphate supply and identifies potential shoot-to-root signals that could vary between different grapevine genotypes

Metabolite profiling during graft union formation reveals the reprogramming of primary metabolism and the induction of stilbene synthesis at the graft interface in grapevine

BACKGROUND: Grafting with rootstocks is essential for the culture of many perennial fruit crops and is increasing being used in the production of annual fruits and vegetables. Our previous work based on microarrays showed that transcripts encoding enzymes of both primary and secondary metabolism were differentially expressed during graft union formation in both homo-grafts (a genotype grafted with itself) and hetero-grafts (two different genotypes grafted together). The aim of this study was to profile primary and secondary metabolites, and quantify the activity of phenylalanine ammonia lyase (PAL) and neutral invertase (NI) in the scion and rootstock tissues and the graft interface of homo and hetero-grafts of grapevine 1 month after grafting. Table-top grafting was done on over-wintering stems (canes) of grapevine and the graft interface tissues (containing some woody stem tissues and callus) were compared to the surrounding rootstock and scion tissues. The objective was to identify compounds involved in graft union formation and hetero-grafting responses.[br/] RESULTS: A total of 54 compounds from primary and secondary metabolism (19 amino acids, five primary and 30 secondary compounds metabolites) and the activity of two enzymes were measured. The graft interface was associated with an increase in the accumulation of the branched-chain amino acids, basic amino acids, certain stilbene compounds and higher PAL and NI activity in comparison to the surrounding woody stem tissues. Some amino acids and stilbenes were identified as being accumulated differently between the graft interfaces of the scion/rootstock combinations in a manner which was unrelated to their concentrations in the surrounding woody stem tissues.[br/] CONCLUSIONS: This study revealed the modification of primary metabolism to support callus cell formation and the stimulation of stilbene synthesis at the graft interface, and how these processes are modified by hetero-grafting. Knowledge of the metabolites and/or enzymes required for successful graft union formation offer us the potential to identify markers that could be used by nurseries and researchers for selection and breeding purposes

Metabolite profiling at the graft interface of grapevine

Poste

Acta hortic.

In viticulture, grafting is used to facilitate grapevine cultivation in soils infected with phylloxera, a soil-dwelling insect pest introduced to Europe from America at the end of the 19th century. Successful grafting of plants is a complex biochemical and structural process that begins with an initial wound response, followed by callus formation and the establishment of a functional vascular system between the two grafting partners. Despite the importance of the scion-rootstock interface in viticulture, we know little of the processes involved in forming a successful graft union. Developments at the scion-rootstock interface of grapevine have been studied using a variety of techniques. Morphological developments have been studied using microscopy techniques and X-ray computed tomography, and xylem connectivity has been assessed by using a high- and low-pressure flow meter. Microarrays have been used to identify genes that are differentially expressed between the wood and graft interface tissues of homo-grafts (the same genotype grafted together) and at the graft interface between different scion-rootstock combinations (hetero-grafts). Primary and secondary metabolite profiling has also been done. An overview of the interdisciplinary approaches currently being used to piece together the puzzle of graft union formation in an important woody, perennial crop will be presented