Search

Grafting alters the genetic and anatomical features of plants. Although grafting has been widely applied in plant propagation, the underlying processes that govern the effects of the procedure are not fully understood. Samples were collected to study the long-term influence of grafting on the leaf-shoot morphology, leaf-shoot anatomy, and genetic signature of the grafted plants. Citrulus lanatus (Thunb.) Matsum. & Nakai (cv. Lady) was used as the scion, and Lagenaria siceraria (Molina) Standl (cv. Argentario) as a rootstock. In grafted plants, leaf blades and petioles were 20.92% and 12.82% longer, respectively, while the midrib collenchyma was 35.68% thicker, and the diameter of the vessel member was 11.17% larger than in ungrafted plants. In the stem, grafting affected the arrangement and number of vascular bundles (from 1 to 2 rings). The thickness of the epidermis decreased by 69.79%, and the size of the external fascicular phloem decreased by 23.56%. The diameter of the vessel member of the grafted plants increased by 28.94%. Eight out of ten evaluated primers met the requirements (stability in both watermelons and bottle gourd, tissue-specific). In the genetic tests, we examined whether this change in the gene expression pattern is due to the grafting and, if so, to what extent. Seven out of eight tested Small Auxin Up-Regulated RNA (SAUR) genes were expressed in the ungrafted and grafted C. lanatus lines in four cases; the expression increased by more than 10% after grafting. The morpho-anatomical changes and genetic variation reported in this study for grafted lines of C. lanatus contribute to the understanding of the underlying mechanisms of plant growth observations resulting from grafting.

The global cannabis market is continuously expanding and as a result, the cannabis industry demands new and improved agronomic cultivation practices to increase production efficiency of cannabidiol (CBD), which is valued for its therapeutic benefits. This study investigates the influence of three rootstock types on the survival rate, morphological parameters, and biochemical composition of cannabis: potentially dwarfing rootstocks (PDR), potentially vigorous rootstocks (PVR), and seedlings-as-rootstocks (SAR). Rootstocks were used for grafting two scion genotypes: ‘ScionII’ = chemotype II of industrial hemp, and ‘ScionIII’ = chemotype III of high CBD accumulating variety. Contrary to expectations, PVR and SAR did not outperform PDR on most of the measured variables. SAR showed the highest survival rate of the grafted cannabis plants (40–70%). The rootstock type had a statistically significant influence only on the bud compactness index in ‘ScionII’, with PDR being particularly noticeable. A comparative analysis of the ‘rootstock/scion’ combinations with their controls (non-grafted scions) revealed grafting’s substantial improvement in most traits. Specifically, PDR increased CBD content by 27% in ‘ScionIII’, inflorescence yield and CBD yield per plant increased by 71% and 84%, respectively, when SAR was used in ‘ScionII’. SAR showed to be the most effective rootstock type for CBD production. Our findings suggest grafting as a promising technique for optimizing cannabis’s agronomic and medicinal potential, highlighting the necessity for further research on its underlying mechanisms to refine production efficiency and quality.

To explore the quality rootstocks which impart better quality fruits in mango varieties, we studied the interactive effect of the scion and rootstock using five mango varieties (Mallika, Amrapali, Dashehari, Pusa Arunima, and Pusa Surya) grafted on three rootstocks (Olour, Kurukkan, and K-5). A total of 25 physico-chemical parameters were studied in the five grafted varieties viz., fruit weight, yield efficiency, fruit per plant, pulp percent, total soluble solids (TSS), acidity, physiological loss in weight (PLW), peel thickness, respiration rate, etc., and were found to be altered through scion–rootstock interaction. Among the five mango varieties, Olour rootstock proved best to improve the fruit quality and shelf life using the grafting approach. Physico-chemical-traits-based clustering was unable to precisely group scion varieties according to their grafting rootstock. A total of 35 shelf-life specific markers were designed from ripening genes, such as expansin, polygalactouranase, ethylene insensitive, ethylene sensitive, etc. Of these specific primers, 24 showed polymorphism among the studied genotypes. The gene diversity (GD), allele per locus (An), polymorphism information content (PIC), and major allele frequency (MAF) observed were 0.43, 2.00, 0.34, and 0.63, respectively. Cluster analysis clearly showed that scion grafted on Kurukkan and Olour rootstock, and scion varieties grafted on K-5 rootstock grouped together have more similarity. A total of eight simple sequence repeats loci (SSRs) markers were associated with eight physiological traits. Strong association of SSR loci NMSLC-12 and NMSLC-14 with yield efficiency and fruit weight were observed with a phenotypic variance of 85% and 70%, respectively.

Breadfruit (Artocarpus altilis) is a traditional fruit tree of 15–30 m tall in Oceania. The species is a staple crop for food security in the tropics. Tree loss from tropical windstorms, together with transition toward high-density planting has driven an interest in the dwarf phenotype of the species. Information on dwarfing rootstocks for breadfruit is currently limited. The aim of this study was to assess the performance of breadfruit growth with lakoocha (Artocarpus lakoocha) as rootstocks. We compared the phenotype of breadfruit trees on lakoocha rootstocks with those on self-graft and non-graft within 21 months after grafting. These led to the discovery of a rootstock-induced dwarf trait in breadfruit species. Breadfruit scions on lakoocha rootstocks displayed a reduction in tree height, stem thickness, and internode length, with fewer branches and leaves, resulting in about 32% of the standard height at the end of 21 months after grafting. These suggest lakoocha rootstocks have the potential to control breadfruit tree vigor. Non-structural carbohydrate analysis showed the composite trees exhibited lower hexose concentration in both scion stems and roots, but higher sucrose level in scion stems, and higher starch level in roots. The significance of these parameters in rootstock dwarfing is discussed.

Plant grafting is a maneuver humans learned from nature and has been practiced since ancient times. The technique has long been applied for efficient propagation as well as for the modification of the traits of interest, such as stress tolerance, tree size, and fruit quality. Since grafting can enhance the environmental tolerance and disease resistance of a plant, its techniques are now used not only in tree species but also among vegetables. Despite such wide advantages of grafting, however, the potential cause behind a compatible graft establishment (scion-rootstock connection) is yet to be fully understood. As compared to succulent herbaceous plants, woody plants often take a longer time for the graft-take and the plants may exhibit incompatible/unsuccessful graft-establishment symptoms within a period ranging from months to years. In this review, we discuss factors involved in a successful/compatible graft establishment along with bottlenecks of our understanding and future perspectives in a simplified manner- particularly focusing on incompatible graft formation on fruit trees based on earlier studies in the field.

Cut roses are grown throughout the four distinct seasons of spring, summer, autumn, and winter in Korea. Especially in the very hot or cold seasons of summer or winter, the temperature and light environments inside a greenhouse cause abiotic stress on the growth of horticultural crops. In a greenhouse where shade cultivation is performed in summer, the temperature is high and the light intensity is low, whereas in winter when shade cultivation is not performed, both temperature and light intensity are low. This experiment investigated the year-round growth and yield changes of cut roses grafted onto three rootstocks. The root activity of rootstocks was generally higher than that of the scion. The stomata of the grafted cut roses showed morphological changes according to the seasons. Compared with the scion, the stomata of grafted cut roses became smaller and their number increased in summer, whereas only the stomata size increased in winter. The grafted cut roses had characteristics of high photosynthetic efficiency such as photosynthesis rate, stomatal conductance, transpiration rate from rootstocks under harsh environmental conditions including temperature and light intensity, and thus the photosynthetic efficiency was higher than that of the scion. There was no significant change in the yield of grafted cut roses, but flower quality parameters such as the stem height, stem thickness, and weight of grafted cut roses were improved according to the rootstocks compared with those of the scion. In particular, in cut roses grafted with R. multiflora cv. Natal Briar and Rosa indica ‘Major’ rootstocks, the weight increased as the stem lengthened and thickened in spring, autumn, and winter. Therefore, grafting is effective in improving the quality of cut roses grown under abiotic stress caused by harsh temperature and light intensity conditions during winter.

Tomato, which is mainly established with grafted seedlings, is one of the most popular vegetables worldwide with a high nutritional value,. Market demand for grafted seedlings is high in specific seasons; thus, commercial nurseries face a problem of limited space availability during the healing stage. Light quality is an essential parameter during healing that can adjust seedling development towards desirable traits and lead to time and space saving during seedling production. Moreover, transplant shock constitutes another challenge that could limit crop yield. The objective of this study was to evaluate the overall quality of grafted tomato seedlings and their potential adjustment to transplant shock as affected by different light spectra during healing in a chamber. Evaluations were conducted immediately after exiting the healing chamber and after transplantation into pots. Light wavelengths were used from fluorescent lamps (FL) or light-emitting diodes with red (R), blue (B), red–blue combinations with 12 and 24% blue (12B and 24B), and white (W) emitting 11% blue. W enhanced the dry shoot biomass and the root architecture before and after transplantation. 24B led to an increased stem diameter, root development, and phenolic and antioxidant accumulation at both phases of the experiment. 12B enhanced the leaf area before transplantation and root development after transplantation. FL, R and B induced inferior seedling growth compared to the red–blue-containing LEDs, with B performing poorly in almost all tested parameters. Overall, red, including 11–24% blue, provides the optimum light conditions during the healing stage for the production of high-quality grafted tomato seedlings, with advanced capabilities of abiotic stress adaptation to transplant shock.

Nowadays, citrus greening or Huanglongbing is considered the most destructive disease in the citrus industry worldwide. In the Americas and Asia, the disease is caused by the putative pathogen, ‘Candidatus Liberibacter asiaticus’ and transmitted by the psyllid vector, Diaphorina citri. It has been shown that volatile organic compounds (VOC) that are released from citrus leaves attract the psyllid vector. Herein, we tested whether the rootstock influenced the stored VOC profile in the scion leaves and if these influences were altered after infestation with D. citri. The VOC profiles of the hexane-extracted leaves of the mandarin hybrid ‘Sugar Belle’ that were grafted on three different rootstocks (C-35, sour orange (SO), and US-897) with and without infestation with D. citri were studied. The GC-MS analysis showed that the scion VOC profiles of the non-infested control trees were similar to each other, and rootstock was not a strong influence. However, after one month of infestation with D. citri, clear differences in the scion VOC profiles appeared that were rootstock dependent. Although the total scion leaf VOC content did not differ between the three rootstocks, the infestation increased scion monoterpenes significantly on US-897 and C-35 rootstock, increased terpene alcohols on US-897 and SO rootstock, and increased sesquiterpenes on SO. Infestation with D. citri significantly reduced fatty acids and fatty acid esters across all of the rootstocks. Therefore, our results suggest that rootstock choice could influence scions with an inducible volatile defense by enhancing the amounts of VOCs that are available for repelling vectors or for signaling to their natural enemies or parasitoids. According to this study, US-897 may be the best choice among the three that were studied herein, due to its diverse and robust VOC defense response to infestation with D. citri.

Despite the importance of grafting in horticultural crops such as tomato (Solanum lycopersicum L.), the structural changes that occur during the graft establishment are little understood. Using histological techniques, the present work examines the time course of changes on the anatomical structure of the graft junction in functional tomato homografts and compares it to that of heterografts and non-functional grafts. No apparent differences were detected between homo- and heterografts, showing similar tissue development. At 10 days after grafting, the cell walls of the scion and rootstock in the area of the graft junction were thicker than usual. Undifferentiated cells and new vascular tissue emerged from the pre-existing vasculature. Adventitious roots appeared mainly on the scion, arising from the pre-existing vasculature. At 20 days, more pronounced vascular tissue was visible, along with large areas showing vascular connection. At 210 days, vestiges of the changes undergone in graft development were still visible. Generally, non-functional grafts presented layers of necrotic remains and deposition of cell wall material in the cut edges, impeding the suitable scion-rootstock connection. Our results show that accurate changes in pre-existing vasculature and the cell walls of the adhesion line are crucial to the development of functional grafts.

Huanglongbing (HLB) reduces the growth and development of citrus and induces changes in secondary metabolites such as flavonoids, limonoids, and polyamines. Likewise, infected plants have a deficient absorption of nutrients such as zinc, potassium, manganese, and copper. Therefore, the objective of this study was to evaluate the influence of different rootstocks on morphology and mineral changes of Citrus limon and Citrus sinensis cv. Valencia plants inoculated with Candidatus Liberibacter asiaticus. In a greenhouse of the Experimental Station-Autonomous University of Tamaulipas, the Candidatus Liberibacter asiaticus bacteria were inoculated to Citrus limon plants (growing on Citrus volkameriana, Citrus macrophylla, and Citrus aurantium rootstocks) and Citrus sinensis cv. Valencia (growing on Citrus volkameriana and Citrus aurantium rootstocks). The experiment was established under a completely randomized design with 45 graft/rootstock repetitions. In each graft/rootstock combination, the plant height and stem diameter were determined using a tape measurer and a Vernier, respectively. In addition, the nutrient content of foliar samples was determined by an X-ray fluorescence spectrometer. In both citrus species, the C. aurantium rootstock promoted a higher concentration of the bacteria. On the other hand, the rootstock that showed the best agronomical results after inoculation with the bacteria was C. volkameriana, presenting the least variation in mineral content and conferring greater plant height (15%) and stem diameter (23%). In contrast, the presence of Ca. Liberibacter asiaticus decreased S content and increased Cu concentration in C. lemon plants. Similarly, plants infected with C. sinensis presented higher Fe content. Finally, in both species, no significant differences were observed for Mn, P, and Zn concentration.

Plant grafting is an important horticulture technique used to produce a new plant after joining rootstock and scion. This is one of the most used techniques by horticulturists to enhance the quality and production of various crops. Grafting helps in improving the health of plants, their yield, and the quality of plant products, along with the enhancement of their postharvest life. The main process responsible for successful production of grafted plants is the connection of vascular tissues. This step determines the success rate of grafts and hence needs to be studied in detail. There are many factors that regulate the connection of scion and stock, and plant hormones are of special interest for researchers in the recent times. These phytohormones act as signaling molecules and have the capability of translocation across the graft union. Plant hormones, mainly auxins, cytokinins, and gibberellins, play a major role in the regulation of various key physiological processes occurring at the grafting site. In the current review, we discuss the molecular mechanisms of graft development and the phytohormone-mediated regulation of the growth and development of graft union.

Grafting is a widely utilized agronomical technique to improve yield, disease resistance, and quality of fruit and vegetables. This work aims to assess the effect of grafting and fruit ripening on the production, physico-chemical characteristics, and nutritional quality of fruit from Spanish local pepper landraces. Landraces "Cuerno," "Sueca," and "Valencia" were used as scions, and "NIBER ® " as the rootstock. Two ripening stages of the fruits were sampled: green and red. Grafting improved the yield and marketable quality and did not negatively influence the physico-chemical and nutritional characteristics of the fruit. It was noteworthy that the bioactive compound contents and antioxidant capacity were more related to maturity stage and genotype, and red fruit had a higher antioxidant capacity than green fruit. However, in all the scions, grafting significantly enhanced lycopene content in both red and green fruit. Another important effect of grafting was the volatile compound composition evidenced by discriminant analyses, which was characterized for the first time in the fruit of these landraces. The rootstock and scion combination could be a way to improve not only the production, but also the fruit quality of peppers.