Scion and Rootstock Differently Influence Growth, Yield and Quality Characteristics of Cherry Tomato

Comparative Stem Transcriptome Analysis Reveals Pathways Associated with Drought Tolerance in Maritime Pine Grafts

The maritime pine (Pinus pinaster Ait.) is a highly valuable Mediterranean conifer. However, recurrent drought events threaten its propagation and conservation. P. pinaster populations exhibit remarkable differences in drought tolerance. To explore these differences, we analyzed stem transcriptional profiles of grafts combining genotypes with contrasting drought responses under well-watered and water-stress regimes. Our analysis underscored that P. pinaster drought tolerance is mainly associated with constitutively expressed genes, which vary based on genotype provenance. However, we identified key genes encoding proteins involved in water stress response, abscisic acid signaling, and growth control including a PHD chromatin regulator, a histone deubiquitinase, the ABI5-binding protein 3, and transcription factors from Myb-related, DOF NAC and LHY families. Additionally, we identified that drought-tolerant rootstock could enhance the drought tolerance of sensitive scions by regulating the accumulation of transcripts involved in carbon mobilization, osmolyte biosynthesis, flavonoid and terpenoid metabolism, and reactive oxygen species scavenging. These included genes encoding galactinol synthase, CBL-interacting serine/threonine protein kinase 5, BEL1-like homeodomain protein, dihydroflavonol 4-reductase, and 1-deoxy-D-xylulose-5-phosphate. Our results revealed several hub genes that could help us to understand the molecular and physiological response to drought of conifers. Based on all the above, grafting with selected drought-tolerant rootstocks is a promising method for propagating elite recalcitrant conifer species, such as P. pinaster.

Qualitative Characteristics and Functional Properties of Cherry Tomato under Soilless Culture Depending on Rootstock Variety, Harvesting Time and Bunch Portion

Tomato grafting is an effective practice in increasing the profitability of fresh-market tomato cultivation, especially in greenhouses, and is also considered a strategy for enhancing fruit quality. In this study, selected quanti-qualitative traits, and the of bioactive health-promoting compound and organic acid contents of cherry tomato fruits from three different scion/rootstock combinations (Sunstream/Top Bental, Sunstream/Kaiser and Sunstream/Suzuka) grown under a greenhouse hydroponic system were evaluated in three different harvests (beginning, middle and end of the whole harvesting period) and on three different bunch portions (proximal, central and distal). Although the tomato productive performance was influenced by the rootstock, with Suzuka and Kaiser grafted plants showing the highest total marketable yield (9.8 kg plant-1, i.e., 20% more than Top Bental), the yield-related traits (bunch number, weight and length per plant, and fruit number per bunch) and the qualitative characteristics of the fruits (color, equatorial and polar diameters, dry matter and solid soluble contents, pH and titratable acidity) showed less variability, by displaying, along with the bioactive compound contents (total polyphenols, lycopene, β-carotene), DPPH free radical scavenging activity and organic acids contents (lactic and acetic), a significant effect of the harvesting time and bunch portion. Fruits from the beginning of the harvesting period showed better qualitative and functional properties, with the lycopene and β-carotene contents equal to 178.6 and 3 mg 100 g-1 fw, and fruits from proximal and central bunch portions had lycopene and β-carotene contents equal to 203.1 and 2.9 mg 100 g-1 fw.

Arabidopsis CDF3 transcription factor increases carbon and nitrogen assimilation and yield in trans-grafted tomato plants

Grafting in tomato (Solanum lycopersicum L.) has mainly been used to prevent damage by soil-borne pathogens and the negative effects of abiotic stresses, although productivity and fruit quality can also be enhanced using high vigor rootstocks. In the context of a low nutrients input agriculture, the grafting of elite cultivars onto rootstocks displaying higher Nitrogen Use Efficiency (NUE) supports a direct strategy for yield maximization. In this study we assessed the use of plants overexpressing the Arabidopsis (AtCDF3) or tomato (SlCDF3) CDF3 genes, previously reported to increase NUE in tomato, as rootstocks to improve yield in the grafted scion under low N inputs. We found that the AtCDF3 gene induced greater production of sugars and amino acids, which allowed for greater biomass and fruit yield under both sufficient and limiting N supplies. Conversely, no positive impact was found with the SlCDF3 gene. Hormone analyses suggest that gibberellins (GA4), auxin and cytokinins (tZ) might be involved in the AtCDF3 responses to N. The differential responses triggered by the two genes could be related, at least in part, to the mobility of the AtCDF3 transcript through the phloem to the shoot. Consistently, a higher expression of the target genes of the transcription factor, such as glutamine synthase 2 (SlGS2) and GA oxidase 3 (SlGA3ox), involved in amino acid and gibberellin biosynthesis, respectively, was observed in the leaves of this graft combination. Altogether, our results provided further insights into the mode of action of CDF3 genes and their biotechnology potential for transgrafting approaches.

Quality Traits and Nutritional Components of Cherry Tomato in Relation to the Harvesting Period, Storage Duration and Fruit Position in the Truss

It is well known that the harvesting period and the storage duration have a significant effect on the quality characteristics of cherry tomato fruits. On the other hand, the effect of the fruit position in the truss has not been studied, as well as the relative contribution of each one of these factors on fruit quality. For this purpose, cherry tomato (Genio F1) whole trusses were harvested at the fruit red ripe stage during three periods. At each harvesting period, the first four (at the base of the truss) and the last four (at the top) fruits from each truss that was previously trimmed to 10 fruits, were stored at 12 °C for 0, 4 and 10 days. At the end of each storage duration, the external color, firmness, antioxidant capacity, pH and titratable acidity, as well as dry matter, soluble solid, total soluble phenol, lycopene, total carotenoid and β-carotene content, were determined. Analysis of variance (ANOVA) indicated that the harvesting period had the most significant effect on skin color parameters L * and C * and β-carotene, as well as on antioxidant capacity, total soluble phenols, dry matter and total soluble solids, while it also had an appreciable effect on titratable acidity. The storage duration had a dominant effect on firmness, total carotenoids and lycopene, while it had an appreciable effect on skin color parameter L * as well. On the other hand, the fruit position in the truss exerted an exclusive effect on h^o and a */b * ratio skin color parameters and pH and an appreciable effect on titratable acidity.

A systematic assessment of how rootstock growth characteristics impact grafted tomato plant biomass, resource partitioning, yield, and fruit mineral composition

The appropriate selection of rootstock-scion combinations to improve yield and fully realize grafting benefits requires an in-depth understanding of rootstock-scion synergy. Toward this end, we grafted two determinate-type scions [grape tomato ('BHN 1022') and beefsteak tomato ('Skyway')] onto four rootstocks with different characteristics to examine plant growth, yield performance, biomass production, and fruit mineral nutrient composition. The study was conducted during two growing seasons (spring and fall plantings in Florida) under organic production in high tunnels with the non-grafted scions as controls. Rootstocks had previously been designated as either "generative" ('Estamino') or "vegetative" ('DR0141TX') by some commercial suppliers or had not been characterized ['RST-04-106-T' and 'SHIELD RZ F1 (61-802)']. Also, 'Estamino', 'DR0141TX', and 'RST-04-106-T' had been described as more vigorous than 'SHIELD RZ F1 (61-802)'. In both planting seasons (with low levels of soilborne disease pressure), the "vegetative" and "generative" rootstocks increased marketable and total fruit yields for both scions except for the beefsteak tomato grafted with the "vegetative" rootstock in fall planting. Positive effects of 'RST-04-106-T' on fruit yield varied with scions and planting seasons, and were most manifested when grafted with the beefsteak tomato scion in fall planting. 'SHIELD RZ F1 (61-802)' led to similar yields as the non-grafted controls except for grafting with the grape tomato scion in fall planting. For vegetative and fruit biomass, both the "vegetative" and "generative" rootstocks had positive impacts except for the beefsteak tomato in fall planting. For fruit mineral composition, the "vegetative" and "generative" rootstocks, both highly vigorous, consistently elevated fruit P, K, Ca, Zn, and Fe contents on a dry weight basis, whereas the other rootstocks did not. Overall, although the more vigorous rootstocks enhanced tomato plant productivity and fruit minerals, the evidence presented here does not support the suggestion that the so-called "vegetative" and "generative" rootstocks have different impacts on tomato scion yield, biomass production, or fruit mineral contents. More studies with different production systems and environmental conditions as well as contrasting scion genotypes are needed to further categorize the impacts of rootstocks with different vigor and other characteristics on plant biomass production and their implications on fruit yield development.

Instrumental and sensory analyses of fruit quality attributes of grafted grape tomatoes in high tunnel organic production systems

BACKGROUND

'Vegetative' and 'generative' tomato rootstock types have been proposed based on their different effects on tomato scion growth performance; however, their impacts on fruit quality have not been characterized. No study has been conducted in which the effects of rootstock on grape tomato quality attributes were assessed using sensory and instrumental methods of evaluation. Here, we conducted two experiments to examine the influence of 'DR0141TX', 'Estamino', and 'Multifort' rootstocks (vegetative, generative, and uncharacterized, respectively) on fruit quality properties of determinate and indeterminate grape tomato scions under organic production in high tunnels, including color, size, firmness, dry matter content, soluble solids content (SSC), titratable acidity (TA), pH, and consumer sensory attributes.

RESULTS

In both experiments, grafting 'Sweet Hearts' indeterminate grape tomato onto 'DR0141TX', 'Estamino', or 'Multifort' increased fruit size and led to negligible effects on sensory attributes and instrumental measurements of fruit quality attributes. For 'BHN 1022' determinate grape tomato, rootstocks did not exhibit any major impact on fruit quality attributes in Experiment 1. However, fruit quality was compromised by grafting per se and rootstocks, especially 'Multifort', in Experiment 2, as reflected by reduced SSC, TA, and SSC/TA and lower scores for overall appearance, overall acceptability, tomato flavor, overall texture, and sweetness.

CONCLUSION

In general, 'vegetative' and 'generative' rootstocks showed comparable effects on sensory evaluations and instrumental measurements of grape tomato quality attributes for both indeterminate and determinate scions. More research is needed to better characterize rootstock effects on fruit quality, including the flavor-related compounds under different growing conditions. © 2022 Society of Chemical Industry.

Yield and Compositional Profile of Eggplant Fruits as Affected by Phosphorus Supply, Genotype and Grafting

The present experiment addressed the effects of two phosphorus regimes (30 and 90 kg ha−1, hereafter P30 and P90) on yield and composition of eggplant fruits in ‘Birgah’ and ‘Dalia’, whether or not these cultivars were grafted onto Solanum torvum ‘Espina’. The P30 regime did not reduce yield, and promoted fruits’ dry matter and total phenols content, along with their concentrations of macronutrients, mesonutrients (S and Na) and micronutrients (mostly Cu, B, Zn); however, their Fe concentrations were depressed. The rootstock ‘Espina’ increased fruit yield, dry matter content, epicarp chroma (in ‘Birgah’) and Ca content, together with their concentrations of B and Zn (especially at P30), but reduced their Fe content, mostly under P30. Thus, the reduced P supply and grafting proved to be effective tools to enhance fruit yield, carpometric and almost all nutritional traits in eggplant, in a framework of more sustainable crop management. However, the reduced fruit concentration of Fe suggests that the affinity of the rootstock with specific micro minerals should be taken into account, along with the option to adopt complementary practices (e.g., targeted micronutrient fertilizations) to manage the micro mineral composition of eggplants.

Leveraging a graft collection to develop metabolome-based trait prediction for the selection of tomato rootstocks with enhanced salt tolerance

Grafting has been demonstrated to significantly enhance the salt tolerance of crops. However, breeding efforts to develop enhanced graft combinations are hindered by knowledge-gaps as to how rootstocks mediate scion-response to salt stress. We grafted the scion of cultivated M82 onto rootstocks of 254 tomato accessions and explored the morphological and metabolic responses of grafts under saline conditions (EC = 20 dS m^-1) as compared to self-grafted M82 (SG-M82). Correlation analysis and Least Absolute Shrinkage and Selection Operator were performed to address the association between morphological diversification and metabolic perturbation. We demonstrate that grafting the same variety onto different rootstocks resulted in scion phenotypic heterogeneity and emphasized the productivity efficiency of M82 irrespective of the rootstock. Spectrophotometric analysis to test lipid oxidation showed largest variability of malondialdehyde (MDA) equivalents across the population, while the least responsive trait was the ratio of fruit fresh weight to total fresh weight (FFW/TFW). Generally, grafts showed greater values for the traits measured than SG-M82, except for branch number and wild race-originated rootstocks; the latter were associated with smaller scion growth parameters. Highly responsive and correlated metabolites were identified across the graft collection including malate, citrate, and aspartate, and their variance was partly related to rootstock origin. A group of six metabolites that consistently characterized exceptional graft response was observed, consisting of sorbose, galactose, sucrose, fructose, myo-inositol, and proline. The correlation analysis and predictive modelling, integrating phenotype- and leaf metabolite data, suggest a potential predictive relation between a set of leaf metabolites and yield-related traits.