Intraspecific Grafting Research Articles

A graft that crafts nontransgenic and genome-edited plants

Grafting in plants facilitates the transmission of biomolecules across the union formation. Recently, Yang et al. demonstrated that inter- and intraspecific grafting in plants can be exploited for trafficking tRNA-tagged mobile reagents of the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system from the transgenic rootstock to wild-type scion for genetic improvement in plants through targeted mutagenesis.

Exploring graft incompatibility markers: Intraspecific and interspecific grafts of tomato (Solanum lycopersicum L.)

Grafting is an innovative and cost-efficient technique commonly practiced in solanaceous crops such as tomato (Solanum lycopersicum L.). However, incompatibility limits the far-reaching grafting approaches in sustainable food production worldwide. An early and precise graft incompatibility detection will have great significance, since graft compatibility between rootstock and scion is a pre-requisite for a successful grafting. The current study examined graft incompatibility in tomato self-grafts (Roma tomato grafted on Roma tomato), intraspecific grafts (Roma tomato grafted on Super red tomato) and interspecific grafts (Roma tomato grafted on Eggplant and Pepper plant) at 4, 8 and 16 DAG (days after grafting) to explore physiological, biochemical and metabolic changes at the graft junction that might be used as graft incompatibility markers. Results revealed that among grafted combinations intraspecific grafts depicted a vigorous resistance against oxidative damage by accumulating low hydrogen peroxide, minimum membrane permeability and lipid peroxidation coupled with high antioxidants activity compared to other grafted combinations while interspecific grafts with low survival rates showed high accumulation of total phenolic and flavonoid content at all three grafting stages (4, 8 and 16 DAG). During histological examinations of graft junctions, an apparent long adherence region at the graft junction of self-grafts and intraspecific grafts were observed while interspecific grafts present a small adhesion line. These variations at the structural, physiological and metabolic level may regulate incompatibility and may serve as markers for early detection of graft incompatibility. These findings may further help in the development of markers at molecular level valuable in rootstock development programs.

Grafting Compatibility, Scion Growth, and Fusarium Wilt Disease Incidence of Intraspecific Grafted Tomato

Abstract The tomato (Solanum lycopersicum L.) is one of the most important vegetables grown globally. However, the production of tomatoes is restricted by Fusarium oxysporum f. sp. lycopersici (Fol). This study aims to investigate the ability of Fol-resistant tomato genotypes to be a rootstock for the susceptible cultivar. In this study, a tomato cultivar was grafted on rootstocks of the same species (intraspecific), and grafting compatibility, peroxidase gene expression, and fusarium wilt disease incidence of tomato scion was evaluated. A Fol-susceptible tomato ‘Sidathip 3’ (SDT3) was grafted onto four different Fol-resistant tomato genotypes and compared with self-grafted cultivar/cultivar and rootstock/rootstock. The survival rate of all grafted plants was 100% at 20 days after grafting (DAG) without significant differences in incompatibility evaluated at 42 days after grafting. The expression of the peroxidase gene (Solyc02g084800.2) using the qPCR technique was compared in self-grafted rootstock LE472/LE472 and SDT3/LE472. The expression level was three times higher in heterografted plants than in self-grafted ones at 15 DAG, indicating graft incompatibility. The rootstocks did not affect the height of the plant, the number of branches, the size of the fruit, or the yield of SDT3 scion. All intraspecific heterografted plants significantly controlled Fol when evaluated 60 days after inoculation. These results showed the usefulness of intraspecific grafting by using the proper rootstock genotypes to increase pathogen resistance in addition to stimulating growth and fruit yield.

The dynamic changes of tracheary elements in an intraspecific quinoa (Chenopodium quinoa) graft

Vascular connection is key to successful graft. Little study has been devoted to the behavior of tracheary elements (TEs), the basic component of vascular bundles, during vascular connection between scion and rootstock. Here we report the structural changes of TEs at the graft interface between two quinoa cultivars, Qaidam White-1 (QW1) and Qaidam Red-1 (QR1). Our results showed that TEs in ungrafted plants developed following an ontogenetic sequence, i.e., the annular vessel, helical vessel, scalariform vessel, reticulate vessel, and pitted vessel. However, this process was greatly accelerated in grafted plants, resulting in quick developmental transition of TE wall patterning. At the early stage of intraspecific grafting (e.g., 5 days after grafting), the membrane-like cellular patches were heavily accumulated at the graft interface but quickly retreated within 2–4 days, suggesting an early emergency response to grafting. The TE length in both scion and rootstock was significantly shorter (more than 50% on average, nTE = 747) than the ungrafted plants in the same period. These short TEs were gradually integrated into a long, continuous conduit, thereby enabling the functional vasculature at the graft union. In addition, the pit size was gradually reduced, for example, for the surface area of outer pit aperture, from 12.73 ± 3.15 to 5.40 ± 0.30 μm2, or for the surface area of inner pit aperture, from 9.34 ± 3.33 to 1.96 ± 1.04 μm2, in 18 days (npits = 2830). Taken together, the morphological changes of TEs and cellular responses to grafting in the intraspecific grafts seemed to be conservative to other homografts and heterografts, implying that these behavioral changes are highly adaptive to the scion–rootstock interaction.

Physico-chemical and postharvest quality characteristics of intra and interspecific grafted tomato fruits

The objective of this study was to evaluate the physico-chemical and postharvest quality characteristics of intra- and interspecific grafted tomato fruit. Anna F1, a commercial tomato variety was interspecifically (Tomato Scion and African eggplant rootstock ( Solanum aethiopicum) ) and intraspecifically (Tomato Scion and bacterial wilt resistant hybrid tomato rootstock) grafted. The tomatoes were grown in a greenhouse and harvested at mature green, turning and ripe stages respectively. The tomatoes were analyzed for size, weight, cumulative weight loss, color changes, texture, respiration and ethylene gas production rates, vitamin C and lycopene content. Interspecific grafting on Manyire green, AB2, and intraspecific grafting on Armada, and B.B rootstocks significantly improved physical and physiological attributes of the tomato fruit. There was significant difference (p < 0.05) in size and weight of grafted tomatoes and control at all the three maturity stages. Intraspecific grafted tomato fruits on Armada rootstocks had the best quality characteristics in terms of firmness, low weight loss, respiration and ethylene production rates which are associated with extended postharvest shelf-life. Intraspecific grafting reduced respiration and ethylene gas production rates with tomatoes grafted onto Armada rootstocks attaining the least climacteric peaks of 20.20 ml CO 2 Kg -1 h -1 and 0.34 μL C 2 H 4 Kg -1 h -1 respectively at mature green stage, thus leading to extendend postharvest life of these tomatoes. Tomatoes grafted onto B.B rootstock had the highest vitamin C content (28.11 mg/100 g). In general, intraspecific grafting recorded the best quality traits over the interspecific grafting. However interspecific grafting of tomato onto African eggplant Manyire and AB2 rootstocks had lower but comparable fruit quality to intraspecific grafting. • The effect of grafting on tomato quality is dependent on scion/rootstock combination. • Tomatoes from Manyire and AB2 rootstocks grafts (interspecific), and Armada and B.B rootstocks (intraspecific) had improved physical, physiological qualities as compared to nongrafted control. • Fruits from the Armada rootstock reported the best quality characteristics in terms of firmness and low weight loss, respiration and ethylene production rates which are associated with prolonging shelf-life. • Lycopene content was not affected by grafting. • In general, intraspecific grafting had the best quality traits over the interspecific grafting. However interspecific grafting of tomato onto African eggplant Manyire and AB2 rootstocks has comparable fruit quality to intraspecific grafting especially for resource poor farmers.

Integrated DNA methylation, transcriptome and physiological analyses reveal new insights into superiority of poplars formed by interspecific grafting.

Plant grafting has a long history and it is extensively employed to improve plant performance. In our previous research, reciprocal grafts of Populus cathayana Rehder (C) and Populus deltoides Bart. Ex Marsh (D) were generated. The results showed that interspecific grafting combinations (scion/rootstock: C/D and D/C) grew better than intraspecific grafting combinations (C/C and D/D). To further understand differences in molecular mechanisms between interspecific and intraspecific grafting, we performed an integrated analysis, including bisulfite sequencing, RNA sequencing and measurements of physiological indicators, to investigate leaves of different grafting combinations. We found that the difference at the genome-wide methylation level was greater in D/C vs D/D than in C/D vs C/C, but no difference was detected at the transcription level in D/C vs D/D. Furthermore, the grafting superiority of D/C vs D/D was not as strong as that of C/D vs C/C. These results may be associated with the different methylation forms, mCHH (71.76%) and mCG (57.16%), that accounted for the highest percentages in C/D vs C/C and D/C vs D/D, respectively. In addition, the interspecific grafting superiority was found mainly related to the process of photosynthesis, phytohormone signal transduction, biosynthesis of secondary metabolites, cell wall and transcriptional regulation based on both physiological and molecular results. Overall, the results indicated that the physiological and molecular phenotypes of grafted plants are affected by the interaction between scion and rootstock. Thus, our study provides a theoretical basis for developing suitable scion-rootstock combinations for grafted plants.

Graft survival of Pinus engelmannii Carr. in relation to two grafting techniques with dormant and sprouting buds.

Developing methods for successfully grafting forest species will be helpful for establishing asexual seed orchards and increasing the success of forest genetic improvement programs in Mexico. In this study we investigated the effects of two grafting techniques (side veneer and top cleft) and two phenological stages of the scion buds (end of latency and beginning of sprouting), in combination with other seven grafting variables, on the sprouting and survival of 120 intraspecific grafts of Pinus engelmannii Carr. The scions used for grafting were taken from a 5.5-year-old commercial forest plantation. The first grafting was performed on January 18 (buds at the end of dormancy) and the second on February 21 (buds at the beginning of sprouting). The data were examined by analysis of variance and a test of means and were fitted to two survival models (the Weibull’s accelerated failure time and the Cox’s proportional hazards model) and the respective hazard ratios were calculated. Survival was higher in the top cleft grafts made with buds at the end of latency, with 80% sprouting and an estimated average survival time of between 164 and 457 days after the end of the 6-month evaluation period. Four variables (grafting technique, phenological stage of the scion buds, scion diameter and rootstock height) significantly affected the risk of graft death in both survival models. Use of top cleft grafts with buds at the end of the latency stage, combined with scion diameters smaller than 11.4 mm and rootstock heights greater than 58.5 cm, was associated with a lower risk of death.

Tomato Graft Union Failure Is Associated with Alterations in Tissue Development and the Onset of Cell Wall Defense Responses

Grafting is a technique applied to a considerable number of crops, with tomato standing out. However, this technique is limited by the obtaining of unfunctional grafts, which decrease the success rate and therefore the benefits achieved. The aim of this work was to analyze the failure in intraspecific grafting of tomato plants, focusing on tissue development, cell wall defense reactions, and the distribution of starch and soluble sugars at the graft junction. The success rate in autografts was higher than that of homografts and heterografts. Unfunctional homografts and heterografts showed similar responses: absence of vascular reconnections and lack of adhesion between scion and rootstock, even though callus cell clusters and differentiation of new vasculature were produced. The scions of unfunctional grafts accumulated more starch and soluble sugars than the rootstocks, showing a strong asymmetry in the response. In addition, three types of deposits were observed in the cell walls of unfunctional grafts: lignin, suberin, and callose, with the combined accumulation of more than one of them being frequent, particularly lignin and suberin. These deposits apparently prevent adhesion and seem to be a major cause of graft failure.

Scion-rootstock interaction and drought systemic effect modulate the organ-specific terpene profiles in grafted Pinus pinaster Ait

Intraspecific grafting with selected scions and rootstocks was used to study drought tolerance in the recalcitrant Mediterranean conifer P. pinaster. Conifers store different terpene types in needles, stems and roots, which can be modified by drought, but most studies have focused on a single organ and over selected terpenes which limits understanding of the overall plant response. In this work, terpene profile (160 components among mono-, sesqui-, di-terpenes and resin acids) as well as eco-physiological traits were assessed in needles, roots, and scion and rootstock stems to analyze the drought sensibility of scions and rootstocks on grafted P. pinaster trees. We used two scions from wet (Galicia) and dry (Oria) provenances grafted onto rootstocks showing differences in the efficiency of water use, grown under two different water regimes, well-watered and water stressed. Constitutively, organs showed clearly different qualitative and quantitative terpene profiles, such as a long-term optimized resources allocation, being neutral and acid diterpenes those more discriminant. Environmental factors may selectively affect the regulation of diterpene biosynthesis in needles, since scion provenances determined the variation of their profiles, mainly regarding again neutral and acid diterpenes. Different scion-conferred terpene phenotypes were observed in each organ, having a relevant role isoabienol content. Drought triggered needle/root resin acids redistribution, which may provide higher protection to roots, correlated to the effective water stress endured by plants. Drought sensitivity of scion-rootstock combinations determined the intensity of drought-triggered changes in terpene levels in all organs, suggesting that chemical defense and drought tolerance are somehow interconnected.

Influencia de factores externos e internos en el prendimiento inicial de injertos de Pinus pseudostrobus var. oaxacana (Mirov) Harrison

Introduction: Grafting allows full multiplication of phenotypic and genotypic characteristics of genetically improved trees. Objective: To determine the influence of bud origin, rootstock fertilization, grafting period and grafting techniques on the success of grafting, growth, and survival of intraspecific grafts in Pinus pseudostrobus var. oaxacana (Mirov) Harrison. Materials and methods: The effect of four factors was evaluated ([a] two bud sources, [b] three rootstock fertilization doses, [c] three grafting seasons and [d] two grafting techniques) on the success of grafting, shoot growth (Sg) and survival. An analysis of variance was carried out to determine the effect of factors a, b, c, and d on successful grafting and Sg, and a Log-Rank test was carried out for survival analysis. Results and discussion: Significant differences (P ≤ 0.05) were obtained for factors a, c and d. Grafting during winter (December 2018 and February 2019) using the side-veneer grafts technique and buds coming from Santa Catarina Ixtepeji showed the highest values of successful grafting (≥25.5 %), Sg (≥14.5 cm) and survival (≥20.5 %). Final survival decreased from 100 to 27 % 90 days after grafting. Conclusions: Grafting period, bud origin, and grafting technique, individually or interacting with, are determinant factors for the success of intraspecific grafting on P. pseudostrobus var. oaxacana

Growth Performance of Mature Trees Resulted from Intra and Inter-specific Grafting on Robusta Coffee

To improve yield and cup quality, mature coffee tree as rootstock could be grafted with scion of selected genotype. This research aimed to study growth performance of mature trees resulted from intra and inter-specific grafting on Robusta coffee. The research was arranged in Randomized Complete Block Design with 3 replications. There were 12 treatments of entrees/under-stump genotype for coffee grafting including 8 treatments of intraspecific local Robusta/Robusta grafting and 4 treatments of interspecific coffee grafting of Robusta/Liberica and Arabica/Robusta. The results showed that intraspecific grafting of Robusta/Robusta, Robusta/Liberica, and Arabica/Robusta resulted in grafting mortality of 9.8%, 10.9%, and 24.8%, respectively. Until 28 weeks after grafting, branch growth variables were significantly affected by scion/rootstock of Robusta/Robusta, Robusta/Liberica, and Arabica/Robusta grafting. Grafted Arabica/Robusta coffee showed the poor growth performance. In second year of Robusta/Robusta and Robusta/Liberica growth, generative growth of cherry inflorescence per branch and number of cherries per inflorescence were not affected by scion and rootstock genotypes. Leaf and branch growth were very important variables correlating with other variables.

Grafts of Woody Plants and the Problem of Incompatibility Between Scion and Rootstock (a review)

Received 4.03.2011, received in revised form 11.03.2011, accepted 18.03.2011 Grafting can occur naturally between branches or more often roots of the same species, or artificially via asexual propagation where the tissues of two plants are encouraged to fuse with one another. Artificial grafting is commonly used for propagation to improve qualities of trees grown commercially via selecting for its roots (called the rootstock) and for stem, leaves, flowers or fruits (called the scion). It is often used to reduce the time to flowering and shorten the breeding program, improve quality and yield of fruits and seeds, improve hardiness in response to environmental conditions and pathogens resistance, and change cultivars. Incompatibility between rootstock and scion has been more often observed for inter-specific than intraspecific grafts, and might result in a dieback of a graft. The objective of this paper was to review the recent literature related to graft applications and incompatibility between scion and rootstock. Anatomical studies of incompatible grafts demonstrated a poor vascular connection, vascular discontinuity and phloem degeneration at the union area, which might be detected as early as few weeks after a graft establishment. These vascular fusion problems can disturb water, nutrient and assimilate flows in the plant and might result in a further breakdown of a union area. Incompatibility might be also a result of insufficient plasmodesmatal coupling at an early stage of development within one of the graft partners. Differences in abundance of phenol compounds and starch below and above the graft union, as well as peroxidase amount at the union might serve as biochemical markers of the rootstock/scion incompatibility. Genetically and biochemically similar scions and rootstocks could improve graft compatibility.

Graft Compatibility among Chestnut (Castanea) Species

Graft compatibility was investigated for 15 Chinese chestnut (Castanea mollissima Bl.) cultivars, nine American chestnut [C. dentata (Marsh.) Borkh.] selections, six Japanese chestnut (C. crenata Sieb.) cultivars, and two putative Japanese hybrids on two known rootstocks of Chinese chestnut. Intraspecific grafting of Chinese chestnut resulted in 80% success after two growing seasons. An unusual anatomical structure of the chestnut stem had a significant effect on graft success. The phloem fiber bundles related to graft failure are described in the study. Interspecific grafts of seven American and five Japanese chestnut selections resulted in ≥70% success. The putative Japanese hybrids had a significantly lower success rate (&lt;50%) regardless of rootstocks. A marked graft incompatibility was found in one Japanese/Chinese and two American/Chinese combinations. Graft incompatibility related to morphological abnormalities at the graft union was also observed in interspecific grafts. Comparisons of cambial isoperoxidase isozymes between successful and unsuccessful grafts did not support the hypothesis that peroxidase isozymes are indicators of rootstock-scion compatibility. The results suggest that genetic incompatibility is not a major cause of graft failure in Chinese chestnut.

Ecological Consequences of Root Grafting in Tabonuco (Dacryodes excelsa) Trees in the Luquillo Experimental Forest, Puerto Rico

Root grafting was commonly found in tabonuco (Dacryodes excelsa Vahl), a dominant tree species of tabonuco forest in the subtropical wet forest of Puerto Rico. Over 90 percent of all stems and basal area of tabonuco occurred in unions, clumps of trees interconnected by root grafts. Self and intraspecific grafting were extensive, while interspecific grafting was not common in tabonuco trees. Seedlings and saplings did not show any grafting, probably because of their size or age. Grafted trees were taller and had a smaller crown/DBH ratio. Hurricane damage was significantly higher in isolated individual tabonuco trees than those in unions. Weak relationships between diameter class, area, and size of union, and inter-tree distances and the sum of the trunk circumferences of the two nearest neighbors suggested that a noncompetitive force such as root grafting was more important than competitive forces in maintaining the unions of tabonuco, and thus the forest community (...)

Phytophthora lateralis . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Phytophthora lateralis . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Chamaecyparis lawsoniana, C. lawsoniana var. ellwoodii, Rhododendron spp., Thuja orientalis [Platycladus orientalis] . DISEASE: Root rot of Lawson's cypress; a facultatively necrotrophic plant pathogen. The first symptom seen is wilting and fading of the bright green foliage at the branch tips nearest the soil (36, 505), followed by a colour change in the inner bark tissue from white to red-brown. There is a sharply distinct margin between infected and healthy tissue, usually found on the stem above the ground line, which disappears as the disease progresses. Dying trees are rapidly invaded by Phleosinus bark beetles, which may confuse correct disease diagnosis. GEOGRAPHICAL DISTRIBUTION: North America; Canada (British Columbia), USA (California, Ohio, Oregon, Pennsylvania, Washington State). See IMI Distribution Map No. 473. TRANSMISSION: By zoospores which move rapidly in surface water, or more slowly in saturated soils, to infect fine rootless. They produce hyphae which grow in the inner bark near the cambium and ascend the roots until the stem is girdled. Sporangia were also produced on leaves at 2-25°C when water was present (36, 505, 36, 800), and so zoospores may also be dispersed by rainsplash. Intraspecific grafting of forest tree roots may also provide a pathway for vegetative spread of the mycelium (56, 2248). Spread of the disease is most rapid where trees are planted together closely, along streams or by roadside ditches. Inoculum may be transported from infected soils in mud on vehicles. Survival is probably by oospores or resting spores, which remain viable for a few years after root death.

Alloimmunity in the Gorgonian Coral Swiftia exserta.

This study of histocompatibility demonstrates that the gorgonian Swiftia exserta (Coelenterata, Anthozoan) fulfills the minimal functional criteria of cytotoxicity, specificity, and altered secondary response (memory) that characterize an adaptive immune response. All autografts (self grafts) fused, and all allografts (intraspecific grafts) underwent rejection, which is characterized by rapid and progressive blanching, necrosis, and loss of tissue in the immediate contact area. Initial reactions required 7-9 days to produce 1 mm of necrosis, but after a resting period, a second contact at a new tissue area yielded the same reaction in 3-4 days. After primary sensitization, intervals of up to eight weeks still produced a significantly accelerated secondary response. Significant differences between the reaction times of second set and third party allografts demonstrated recognition specificity in these responses. Thus, this is the first report of an adaptive alloimmune response in gorgonians.

Mapping of neural crest pathways in Xenopus laevis using inter- and intra-specific cell markers

This study examines the pathways of migration followed by neural crest cells in Xenopus embryos using two recently described cell marking techniques. The first is an interspecific chimera created by grafting Xenopus borealis cells into Xenopus laevis hosts. The cells of these closely related species can be distinguished by their nuclear dimorphism. The second type of marker is created by microinjection of lysinated dextrans into fertilized eggs which can then be used for intraspecific grafting. These recently developed fluorescent dyes are fixable and identifiable in both living and fixed embryos. After grafting labeled donor neural tubes into unlabeled host embryos, the distribution of neural crest cells at various stages after grafting was used to define the pathways of neural crest migration. To control for possible grafting artifacts, fluorescent lysinated dextran was injected into a single blastomere which gives rise to a large number of neural crest cells, thereby labeling the neural crest without grafting. By all three techniques, Xenopus neural crest cells were observed along two predominant pathways in the trunk. The majority of neural crest cells were observed along a “ventral” route, between the neural tube and somite, the notochord and somite, and along the dorsal mesentery. A second group of neural crest cells was observed “dorsally” where they populated the dorsal fin. A third minor “lateral” pathway was observed primarily in borealis/laevis chimerae and in blastomere-injected embryos; some neural crest cells were observed underneath the ectoderm lateral to the neural tube. Along the rostrocaudal axis, neural crest cells were not continuously distributed but were primarily located across from the caudal two-thirds of the somite. Fewer than 3% of the neural crest cells were observed across from the rostral third of each somite. When grafted to ventral locations, neural crest cells were not able to migrate dorsally but migrated laterally along the dorsal mesentery. Labeled neural crest cells gave rise to cells of the spinal, sympathetic, and enteric ganglia as well as to adrenal chromaffin cells, Schwann cells, pigment cells, mesenchymal cells of the dorsal fin, and some cells in the integuments and in the region of the pronephros. These results show that the neural crest migratory pathways in Xenopus differ from those in the avian embryo. In avians NC cells migrate as a closely associated sheet of cells while in Xenopus they migrate as individual cells. Both species exhibit a metamerism in the neural crest cell distribution pattern along the rostrocaudal axis. However, in chick embryos NC cells migrate through the rostral sclerotome of each somite and are never observed in the perinotochordal area.

Histo-incompatibility in a natural population of gorgonians

Intraspecific grafts were made between 2430 segments of “wild” gorgonians (Cnidaria). Of the surviving 1479, graft failures represented 96.6%, semi-rejection 2.7% and complete take 0.7%. A gene-dose effect with a two haplotypes difference for non-fusion and a one haplotype difference for semi-rejection could be proposed.

Root Grafting in Quercus Turbinella Greene

Apparent widespread self—grafting and intra—specific grafting roots of Quercus turbinella have been noted in north—central Arizona. Grafting occurred on roots varying in size from 0.1 inch to 1.5 inches in diameter and varying in depth below the soil surface from a few inches to over 25 ft. Cross sections of the grafts indicated sufficient fusion to allow translocation across the unions. Implications of the phenomenon are discussed.