Phenotyping xylem connections in grafted plants using X-ray micro-computed tomography.

Plants are able to naturally graft or inosculate their trunks, branches and roots together, this mechanism is used by humans to graft together different genotypes for a range of purposes. Grafts are considered successful if functional vascular connections between the two genotypes occur. Various techniques can evaluate xylem connections across the graft interface.

Tissue-specific stilbene accumulation is an early response to wounding/grafting as revealed by using spatial and temporal metabolomics.

Grafting is widely used in horticulture. Shortly after grafting, callus tissues appear at the graft interface and the vascular tissues of the scion and rootstock connect. The graft interface contains a complex mix of tissues, we hypothesised that each tissue has its own metabolic response to wounding/grafting and accumulates different metabolites at different rates.

Grafting in plants: recent discoveries and new applications.

Grafting is a traditional horticultural technique that makes use of plant wound healing mechanisms to join two different genotypes together to form one plant. In many agricultural systems, grafting with rootstocks controls the vigour of the scion and/or provides tolerance to deleterious soil conditions such as the presence of soil pests or pathogens or limited or excessive water or mineral nutrient supply. Much of our knowledge about the limits to grafting different genotypes together comes from empirical knowledge of horticulturalists.

Targeting Ultrastructural Events at the Graft Interface of by A Correlative Light Electron Microscopy Approach.

Combining two different plants together through grafting is one of the oldest horticultural techniques. In order to survive, both partners must communicate via the formation of de novo connections between the scion and the rootstock. Despite the importance of grafting, the ultrastructural processes occurring at the graft interface remain elusive due to the difficulty of locating the exact interface at the ultrastructural level.

Identifying early metabolite markers of successful graft union formation in grapevine.

Grafting is an important horticultural technique used for many crop species. However, some scion/rootstock combinations are considered as incompatible due to poor graft union formation and subsequently high plant mortality. The early identification of graft incompatibility could allow the selection of non-viable plants before planting and would have a beneficial impact on research and development in the nursery sector.

A correlative light electron microscopy approach reveals plasmodesmata ultrastructure at the graft interface.

Despite recent progress in our understanding of graft union formation, we still know little about the cellular events underlying the grafting process. This is partially due to the difficulty of reliably targeting the graft interface in electron microscopy to study its ultrastructure and three-dimensional architecture. To overcome this technological bottleneck, we developed a correlative light electron microscopy (CLEM) approach to study the graft interface with high ultrastructural resolution.

Identifying Molecular Markers of Successful Graft Union Formation and Compatibility.

Grafting is a technique used for millennia for vegetative propagation, especially in perennial fruit crops. This method, used on woody and herbaceous plants, can improve several agronomic characteristics, such as yield or vigor, as well as tolerance to biotic and abiotic stresses. However, some scion/rootstock combinations suffer from poor graft compatibility, i.

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.

Polyphenol Profiles of Just Pruned Grapevine Canes from Wild Accessions and Cultivars.

Grapevine canes are an abundant byproduct of the wine industry. The stilbene contents of cultivars have been largely studied, but little is known about the stilbene contents of wild accessions. Moreover, there have only been few studies on the quantification of other phenolic compounds in just pruned grapevine canes.

Dissecting the control of shoot development in grapevine: genetics and genomics identify potential regulators.

Background: Grapevine is a crop of major economic importance, yet little is known about the regulation of shoot development in grapevine or other perennial fruits crops. Here we combine genetic and genomic tools to identify candidate genes regulating shoot development in Vitis spp.

Results: An F2 population from an interspecific cross between V.

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.

Merging genotypes: graft union formation and scion-rootstock interactions.

Grafting has been utilised for at least the past 7000 years. Historically, grafting has been developed by growers without particular interest beyond the agronomical and ornamental effects, and thus knowledge about grafting has remained largely empirical. Much of the commercial production of fruit, and increasingly vegetables, relies upon grafting with rootstocks to provide resistance to soil-borne pathogens and abiotic stresses as well as to influence scion growth and performance.

Phosphorus acquisition efficiency and phosphorus remobilization mediate genotype-specific differences in shoot phosphorus content in grapevine.

Crop productivity is limited by phosphorus (P) and this will probably increase in the future. Rootstocks offer a means to increase the sustainability and nutrient efficiency of agriculture. It is known that rootstocks alter petiole P concentrations in grapevine.

Potential contribution of strigolactones in regulating scion growth and branching in grafted grapevine in response to nitrogen availability.

In grafted plants, rootstocks assure the mineral nutrition of the scion and modify its development. In this study, we show that two grapevine rootstock genotypes have different shoot branching architectures when cultivated as cuttings and that this trait is transmitted to the scion when grafted. Shoot branching plasticity in response to nitrogen supply was also studied.

Genetic architecture of aerial and root traits in field-grown grafted grapevines is largely independent.

QTLs were identified for traits assessed on field-grown grafted grapevines. Root number and section had the largest phenotypic variance explained. Genetic control of root and aerial traits was independent.

Root transcriptomic responses of grafted grapevines to heterogeneous nitrogen availability depend on rootstock genotype.

In many fruit species, including grapevine, grafting is used to improve scion productivity and quality and to adapt the plant to environmental conditions. However, the mechanisms underlying the rootstock control of scion development are still poorly understood. The ability of rootstocks to regulate nitrogen uptake and assimilation may contribute to this control.

ABA-mediated responses to water deficit separate grapevine genotypes by their genetic background.

Background: ABA-mediated processes are involved in plant responses to water deficit, especially the control of stomatal opening. However in grapevine it is not known if these processes participate in the phenotypic variation in drought adaptation existing between genotypes. To elucidate this question, the response to short-term water-deficit was analysed in roots and shoots of nine Vitis genotypes differing in their drought adaptation in the field.

Temporal kinetics of the transcriptional response to carbon depletion and sucrose readdition in Arabidopsis seedlings.

To investigate whether the transcriptional response to carbon (C) depletion and sucrose resupply depends on the duration and severity of the C depletion, Arabidopsis seedlings were grown in liquid culture and harvested 3, 6, 12, 24, 48 and 72 h after removing sucrose from the medium and 30 min after resupplying sucrose at each time. Expression profiling revealed early transcriptional inhibition of cell wall synthesis and remodelling of signalling, followed by induction of C recycling and photosynthesis and general inhibition of growth. The temporal sequence differed from the published response to progressive exhaustion of C during a night and extended night in vegetatively growing plants.

Developments at the graft interface in homo- and hetero-grafts: Gene expression and histological changes during the first month after grafting.

Gene expression changes induced during graft union formation (the first month after grafting) in grapevine have been studied using whole genome microarrays. The genes differentially expressed between the rootstock and graft interface tissues of homo-grafts (Cabernet Sauvignon (CS) grafted onto CS) were compared at 3 and 28 days after grafting (dag). Graft union formation was associated with the upregulation of genes involved in secondary metabolism, cell wall, wound responses and hormone signaling.

Phenotyping the kinematics of leaf development in flowering plants: recommendations and pitfalls.

Leaves of flowering plants are produced from the shoot apical meristem at regular intervals and they grow according to a developmental program that is determined by both genetic and environmental factors. Detailed frameworks for multiscale dynamic analyses of leaf growth have been developed in order to identify and interpret phenotypic differences caused by either genetic or environmental variations. They revealed that leaf growth dynamics are non-linearly and nonhomogeneously distributed over the lamina, in the leaf tissues and cells.

Grafting with rootstocks induces extensive transcriptional re-programming in the shoot apical meristem of grapevine.

Background: Grafting is widely used in the agriculture of fruit-bearing crops; rootstocks are known to confer differences in scion biomass in addition to improving other traits of agricultural interest. However, little is known about the effect of rootstocks on scion gene expression. The objective of this study was to determine whether hetero-grafting the grapevine variety Vitis vinifera cv.

Graft union formation in grapevine induces transcriptional changes related to cell wall modification, wounding, hormone signalling, and secondary metabolism.

Grafting is particularly important to the cultivation of perennial crops such as grapevine (Vitis vinifera) because rootstocks can provide resistance to soil-borne pests and diseases as well as improve tolerance to some abiotic stresses. Successful grafting is a complex biochemical and structural process beginning with the adhesion of the two grafted partners, followed by callus formation and the establishment of a functional vascular system. At the molecular level, the sequence of events underlying graft union formation remains largely uncharacterized.

Grapevine rootstock effects on scion biomass are not associated with large modifications of primary shoot growth under nonlimiting conditions in the first year of growth.

In grapevine (Vitis vinifera L.), rootstocks are known to alter scion development by modifying stem weight and yield. The aim of this work was to evaluate the contribution of primary growth to the rootstock effects on scion biomass.

Do pH changes in the leaf apoplast contribute to rapid inhibition of leaf elongation rate by water stress? Comparison of stress responses induced by polyethylene glycol and down-regulation of root hydraulic conductivity.

We have dissected the influences of apoplastic pH and cell turgor on short-term responses of leaf growth to plant water status, by using a combination of a double-barrelled pH-selective microelectrodes and a cell pressure probe. These techniques were used, together with continuous measurements of leaf elongation rate (LER), in the (hidden) elongating zone of the leaves of intact maize plants while exposing roots to various treatments. Polyethylene glycol (PEG) reduced water availability to roots, while acid load and anoxia decreased root hydraulic conductivity.