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Miyahara T, Ohkubo H, Umeyama Y, Oguchi T, Ogawa T, Ohta D, Mochizuki T, Kodama H. Discontinuous Translocation of a Luciferase Protein beyond Graft Junction in Tobacco. Food Saf (Tokyo) 2024; 12:1-16. [PMID: 38532775 PMCID: PMC10961615 DOI: 10.14252/foodsafetyfscj.d-23-00010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 01/29/2024] [Indexed: 03/28/2024] Open
Abstract
Transgrafting, a grafting technique that uses both genetically modified (GM) and non-GM plants, is a novel plant breeding technology that can be used to improve the efficiency of crop cultivation without introducing foreign genes into the edible parts of non-GM plants. This technique can facilitate the acquisition of disease resistance and/or increased yield. However, the translocation of low-molecular-weight compounds, ribonucleic acid (RNA), and proteins through graft junctions raises a potential safety risk for food crops. Here, we used a transgenic tobacco plant expressing a firefly luciferase gene (LUC) to examine the translocation of the LUC protein beyond the graft junction in grafted plants. We observed the bi-directional translocation of LUC proteins in transgrafted tobacco plants, i.e., from the rootstock to scion and vice versa. Transcriptomic analysis revealed that transcripts of the LUC gene were undetectable in non-GM plant bodies, indicating that the LUC protein itself was translocated. Moreover, the movement of the LUC protein is an episodic (i.e., non-continuous) event, since non-GM samples showing high LUC activity were flanked by non-GM samples showing no apparent LUC activity. Translocation from the GM to non-GM part depends on the characteristics of GM plant bodies; here, the enhanced translocation of the LUC protein into the non-GM scion was observed when LUC-expressing rootstocks with hairy roots were used. Moreover, the quantity of translocated LUC protein was far below the level that is generally required to induce an allergenic response. Finally, since the LUC protein levels of plants used for transgrafting are moderate and the LUC protein itself is relatively unstable, further investigation is necessary regarding whether the newly expressed protein in GM plants is highly stable, easily translocated, and/or highly expressed.
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Affiliation(s)
- Taira Miyahara
- Graduate School of Horticulture, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Hitomi Ohkubo
- Graduate School of Horticulture, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Yukiko Umeyama
- Graduate School of Horticulture, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Taichi Oguchi
- Institute of Life and Environmental Sciences, University of
Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
- Tsukuba Plant Innovation Research Center, University of Tsukuba,
1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Takumi Ogawa
- Graduate School of Agriculture, Osaka Metropolitan University,
1-1 Gakuen-cho, Naka-ku, Sakai,Osaka 599-8531, Japan
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Daisaku Ohta
- Graduate School of Agriculture, Osaka Metropolitan University,
1-1 Gakuen-cho, Naka-ku, Sakai,Osaka 599-8531, Japan
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Tomofumi Mochizuki
- Graduate School of Agriculture, Osaka Metropolitan University,
1-1 Gakuen-cho, Naka-ku, Sakai,Osaka 599-8531, Japan
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Hiroaki Kodama
- Graduate School of Horticulture, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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Estrada Y, Plasencia F, Ortíz-Atienza A, Faura C, Flores FB, Lozano R, Egea I. A novel function of the tomato CALCINEURIN-B LIKE 10 gene as a root-located negative regulator of salt stress. PLANT, CELL & ENVIRONMENT 2023; 46:3433-3444. [PMID: 37555654 DOI: 10.1111/pce.14679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/28/2023] [Accepted: 07/30/2023] [Indexed: 08/10/2023]
Abstract
Climate change exacerbates abiotic stresses like salinization, negatively impacting crop yield, so development of strategies, like using salt-tolerant rootstocks, is crucial. The CALCINEURIN B-LIKE 10 (SlCBL10) gene has been previously identified as a positive regulator of salt tolerance in the tomato shoot. Here, we report a different function of SlCBL10 in tomato shoot and root, as disruption of SlCBL10 only induced salt sensitivity when it was used in the scion but not in the rootstock. The use of SlCBL10 silencing rootstocks (Slcbl10 mutant and RNAi line) improved salt tolerance on the basis of fruit yield. These changes were associated with improved Na+ and K+ homoeostasis, as SlCBL10 silencing reduced the Na+ content and increased the K+ content under salinity, not only in the rootstock but also in the shoot. Improvement of Na+ homoeostasis in Slcbl10 rootstock seems to be mainly due to induction of SlSOS1 expression, while the higher K+ accumulation in roots seems to be mainly determined by expression of LKT1 transporter and SlSKOR channel. These findings demonstrate that SlCBL10 is a negative regulator of salt tolerance in the root, so the use of downregulated SlCBL10 rootstocks may provide a suitable strategy to increase tomato fruit production under salinity.
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Affiliation(s)
- Yanira Estrada
- Dpto. Biología del Estrés y Patología Vegetal, Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas, Espinardo, Murcia, Spain
| | - Félix Plasencia
- Dpto. Biología del Estrés y Patología Vegetal, Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas, Espinardo, Murcia, Spain
| | - Ana Ortíz-Atienza
- Dpto. de Biología y Geología, Centro de Investigación en Biotecnología Agroalimentaria, Universidad de Almería, Almería, Spain
| | - Celia Faura
- Dpto. Biología del Estrés y Patología Vegetal, Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas, Espinardo, Murcia, Spain
| | - Francisco B Flores
- Dpto. Biología del Estrés y Patología Vegetal, Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas, Espinardo, Murcia, Spain
| | - Rafael Lozano
- Dpto. de Biología y Geología, Centro de Investigación en Biotecnología Agroalimentaria, Universidad de Almería, Almería, Spain
| | - Isabel Egea
- Dpto. Biología del Estrés y Patología Vegetal, Centro de Edafología y Biología Aplicada del Segura, Consejo Superior de Investigaciones Científicas, Espinardo, Murcia, Spain
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3
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Ogawa T, Kato K, Asuka H, Sugioka Y, Mochizuki T, Nishiuchi T, Miyahara T, Kodama H, Ohta D. Multi-omics Analyses of Non-GM Tomato Scion Engrafted on GM Rootstocks. Food Saf (Tokyo) 2023; 11:41-53. [PMID: 37745161 PMCID: PMC10514396 DOI: 10.14252/foodsafetyfscj.d-23-00005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 08/07/2023] [Indexed: 09/26/2023] Open
Abstract
Grafting has been widely applied in agricultural production in order to utilize agriculturally valuable traits. The use of genetically modified (GM) plants for grafting with non-GM crops will soon be implemented to generate chimeric plants (transgrafting)*, and the non-GM edible portions thus obtained could fall outside of the current legal regulations. A number of metabolites and macromolecules are reciprocally exchanged between scion and rootstock, affecting the crop properties as food. Accordingly, the potential risks associated with grafting, particularly those related to transgrafting with GM plants, should be carefully evaluated based on scientific evidence. In this study, we prepared a hetero-transgraft line composed of non-GM tomato scion and GM-tobacco rootstock expressing firefly luciferase. We also prepared a homograft line (both rootstock and scion are from non-GM tomato) and a heterograft line (non-GM tobacco rootstock and non-GM tomato scion). The non-GM tomato fruits were harvested from these grafted lines and subjected to comprehensive characterization by multi-omics analysis. Proteomic analysis detected tobacco-derived proteins from both heterograft and hetero-transgraft lines, suggesting protein transfer from the tobacco rootstock to the tomato fruits. No allergenicity information is available for these two tobacco-derived proteins. The transcript levels of the genes encoding two allergenic tomato intrinsic proteins (Sola l 4.0101 and Sola l 4.0201) decreased in the heterograft and hetero-transgraft lines. Several differences were observed in the metabolic profiles, including α-tomatine and nicotine. The accumulation of tobacco-derived nicotine in the tomato fruits of both heterograft and hetero-transgraft lines indicated that the transfer of unfavorable metabolites from rootstock to scion should be assessed as a food safety concern. Further investigations are needed to clarify whether variable environmental conditions and growth periods may influence the qualities of the non-GM edible parts produced by such transgrafted plants.
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Affiliation(s)
- Takumi Ogawa
- Graduate School of Agriculture, Osaka Metropolitan University,
1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Kanae Kato
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Harue Asuka
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Yumi Sugioka
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Tomofumi Mochizuki
- Graduate School of Agriculture, Osaka Metropolitan University,
1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Takumi Nishiuchi
- Division of Life Science, Graduate School of Natural Science and
Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
- Division of Integrated Omics Research, Bioscience Core Facility,
Research Center for Experimental Modeling of Human Disease, Kanazawa University, 13-1
Takaramachi, Kanazawa, Ishikawa 920-8640, Japan
| | - Taira Miyahara
- Graduate School of Horticulture, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Hiroaki Kodama
- Graduate School of Horticulture, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Daisaku Ohta
- Graduate School of Agriculture, Osaka Metropolitan University,
1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
- Graduate School of Life and Environmental Sciences, Osaka
Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
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Lebedev V. Impact of Intron and Retransformation on Transgene Expression in Leaf and Fruit Tissues of Field-Grown Pear Trees. Int J Mol Sci 2023; 24:12883. [PMID: 37629068 PMCID: PMC10454629 DOI: 10.3390/ijms241612883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/26/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
Stable and high expression of introduced genes is a prerequisite for using transgenic trees. Transgene stacking enables combining several valuable traits, but repeated transformation increases the risk of unintended effects. This work studied the stability and intron-mediated enhancement of uidA gene expression in leaves and different anatomical parts of pear fruits during field trials over 14 years. The stability of reporter and herbicide resistance transgenes in retransformed pear plants, as well as possible unintended effects using high-throughput phenotyping tools, were also investigated. The activity of β-glucuronidase (GUS) varied depending on the year, but silencing did not occur. The uidA gene was expressed to a maximum in seeds, slightly less in the peel and peduncles, and much less in the pulp of pear fruits. The intron in the uidA gene stably increased expression in leaves and fruits by approximately twofold. Retransformants with the bar gene showed long-term herbicide resistance and exhibited no consistent changes in leaf size and shape. The transgenic pear was used as rootstock and scion, but grafted plants showed no transport of the GUS protein through the graft in the greenhouse and field. This longest field trial of transgenic fruit trees demonstrates stable expression under varying environmental conditions, the expression-enhancing effect of intron and the absence of unintended effects in single- and double-transformed woody plants.
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Affiliation(s)
- Vadim Lebedev
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 142290 Pushchino, Russia
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5
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Zeng H, Zhang M, Liu H, Liu J, Zhu L, Feng D, Wang J. Two electrochemiluminescence immunosensors for the sensitive and quantitative detection of the CP4-EPSPS protein in genetically modified crops. Food Chem 2023; 428:136818. [PMID: 37421663 DOI: 10.1016/j.foodchem.2023.136818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/02/2023] [Accepted: 07/03/2023] [Indexed: 07/10/2023]
Abstract
Two different models of electrochemiluminescence (ECL) immunosensors for the sensitive and quantitative detection of the CP4-EPSPS protein in genetically modified (GM) crops were proposed in this study. One was a signal-reduced ECL immunosensor based on nitrogen-doped graphene, graphitic carbon nitride and polyamide-amine (GN-PAMAM-g-C3N4) composites as the electrochemically active substance. The other model was a signal-enhanced ECL immunosensor based on a GN-PAMAM modified electrode for the detection of CdSe/ZnS quantum dots (QDs)-labeled antigens. The ECL signal responses of the reduced and enhanced immunosensors linearly decreased as the increase of the soybean RRS and RRS-QDs content in the range of 0.05% to 1.5% and 0.025% to 1.0%, with the limits of detection of 0.03% and 0.01% (S/N = 3), respectively. Both of the ECL immunosensors showed good specificity, stability, accuracy, and reproducibility in the analysis of real samples. The results indicate that the two immunosensors provide an ultra-sensitive and quantitative approach for the determination of the CP4-EPSPS protein. Due to their outstanding performances, the two ECL immunosensors could be useful tools for achieving the effective regulation of GM crops.
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Affiliation(s)
- Haijuan Zeng
- The Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, Key Laboratory of Agricultural Genetics and Breeding, Shanghai 201106, China; Crops Ecological Environment Security Inspection and Supervision Center (Shanghai), Ministry of Agriculture and Rural Affairs, Shanghai 201106, China; Shanghai Co-Elite Agricultural Sci-Tech (Group) Co. Ltd., Shanghai 201106, China
| | - Minghao Zhang
- The Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, Key Laboratory of Agricultural Genetics and Breeding, Shanghai 201106, China; School of Life Science, Yangtze University, Jingzhou 434022, China
| | - Hua Liu
- The Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, Key Laboratory of Agricultural Genetics and Breeding, Shanghai 201106, China; Crops Ecological Environment Security Inspection and Supervision Center (Shanghai), Ministry of Agriculture and Rural Affairs, Shanghai 201106, China
| | - Juan Liu
- School of Public Health, Academician Workstation, Changsha Medical University, Changsha 410219, China
| | - Lemei Zhu
- School of Public Health, Academician Workstation, Changsha Medical University, Changsha 410219, China
| | - Dongsheng Feng
- Shanghai Center of Agri-Products Quality and Safety, Shanghai 200335, China
| | - Jinbin Wang
- The Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, Key Laboratory of Agricultural Genetics and Breeding, Shanghai 201106, China; Crops Ecological Environment Security Inspection and Supervision Center (Shanghai), Ministry of Agriculture and Rural Affairs, Shanghai 201106, China.
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6
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Momo J, Rawoof A, Kumar A, Islam K, Ahmad I, Ramchiary N. Proteomics of Reproductive Development, Fruit Ripening, and Stress Responses in Tomato. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:65-95. [PMID: 36584279 DOI: 10.1021/acs.jafc.2c06564] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The fruits of the tomato crop (Solanum lycopersicum L.) are increasingly consumed by humans worldwide. Due to their rich nutritional quality, pharmaceutical properties, and flavor, tomato crops have gained a salient role as standout crops among other plants. Traditional breeding and applied functional research have made progress in varying tomato germplasms to subdue biotic and abiotic stresses. Proteomic investigations within a span of few decades have assisted in consolidating the functional genomics and transcriptomic research. However, due to the volatility and dynamicity of proteins in the regulation of various biosynthetic pathways, there is a need for continuing research in the field of proteomics to establish a network that could enable a more comprehensive understanding of tomato growth and development. With this view, we provide a comprehensive review of proteomic studies conducted on the tomato plant in past years, which will be useful for future breeders and researchers working to improve the tomato crop.
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Affiliation(s)
- John Momo
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi 110067, India
| | - Abdul Rawoof
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi 110067, India
| | - Ajay Kumar
- Department of Plant Sciences, School of Biological Sciences, Central University of Kerala, Kasaragod, Kerala 671316, India
| | - Khushbu Islam
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi 110067, India
| | - Ilyas Ahmad
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi 110067, India
| | - Nirala Ramchiary
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi 110067, India
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Omics Profiles of Non-GM Tubers from Transgrafted Potato with a GM Scion. Food Saf (Tokyo) 2023; 11:1-20. [PMID: 36970308 PMCID: PMC10034357 DOI: 10.14252/foodsafetyfscj.d-22-00010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/26/2022] [Indexed: 02/13/2023] Open
Abstract
"Transgrafting" is a grafting procedure whereby a transgenic plant body is grafted to a non-transgenic plant body. It is a novel plant breeding technology that allows non-transgenic plants to obtain benefits usually conferred to transgenic plants. Many plants regulate flowering by perceiving the day-length cycle via expression of FLOWERING LOCUS T (FT) in the leaves. The resulting FT protein is translocated to the shoot apical meristem via the phloem. In potato plants, FT is involved in the promotion of tuber formation. Here we investigated the effects of a genetically modified (GM) scion on the edible parts of the non-GM rootstock by using potato plants transformed with StSP6A, a novel potato homolog of the FT gene. Scions prepared from GM or control (wild-type) potato plants were grafted to non-GM potato rootstocks; these were designated as TN and NN plants, respectively. After tuber harvest, we observed no significant differences in potato yield between TN and NN plants. Transcriptomic analysis revealed that only one gene-with unknown function-was differentially expressed between TN and NN plants. Subsequent proteomic analysis indicated that several members of protease inhibitor families, known as anti-nutritional factors in potato, were slightly more abundant in TN plants. Metabolomic analysis revealed a slight increase in metabolite abundance in NN plants, but we observed no difference in the accumulation of steroid glycoalkaloids, toxic metabolites found in potato. Finally, we found that TN and NN plants did not differ in nutrient composition. Taken together, these results indicate that FT expression in scions had a limited effect on the metabolism of non-transgenic potato tubers.
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Sakurai N. Recent applications of metabolomics in plant breeding. BREEDING SCIENCE 2022; 72:56-65. [PMID: 36045891 PMCID: PMC8987846 DOI: 10.1270/jsbbs.21065] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 12/19/2021] [Indexed: 05/27/2023]
Abstract
Metabolites play a central role in maintaining organismal life and in defining crop phenotypes, such as nutritional value, fragrance, color, and stress resistance. Among the 'omes' in biology, the metabolome is the closest to the phenotype. Consequently, metabolomics has been applied to crop improvement as method for monitoring changes in chemical compositions, clarifying the mechanisms underlying cellular functions, discovering markers and diagnostics, and phenotyping for mQTL, mGWAS, and metabolite-genome predictions. In this review, 359 reports of the most recent applications of metabolomics to plant breeding-related studies were examined. In addition to the major crops, more than 160 other crops including rare medicinal plants were considered. One bottleneck associated with using metabolomics is the wide array of instruments that are used to obtain data and the ambiguity associated with metabolite identification and quantification. To further the application of metabolomics to plant breeding, the features and perspectives of the technology are discussed.
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Affiliation(s)
- Nozomu Sakurai
- Bioinformation and DDBJ Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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Omics Profiles of Non-transgenic Scion Grafted on Transgenic RdDM Rootstock. Food Saf (Tokyo) 2022; 10:13-31. [PMID: 35510071 PMCID: PMC9008877 DOI: 10.14252/foodsafetyfscj.d-21-00012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 12/16/2021] [Indexed: 11/21/2022] Open
Abstract
Grafting of commercial varieties onto transgenic stress-tolerant rootstocks is attractive
approach, because fruit from the non-transgenic plant body does not contain foreign genes.
RNA silencing can modulate gene expression and protect host plants from viruses and
insects, and small RNAs (sRNAs), key molecules of RNA silencing, can move systemically.
Here, to evaluate the safety of foods obtained from sRNA-recipient plant bodies, we
investigated the effects of rootstock-derived sRNAs involved in mediating RNA-directed DNA
methylation (RdDM) on non-transgenic scions. We used tobacco rootstocks showing RdDM
against the cauliflower mosaic virus (CaMV) 35S promoter. When scions harboring CaMV 35S
promoter sequence were grafted onto RdDM-inducing rootstocks, we found that RdDM-inducing
sRNAs were only weakly transported from the rootstocks to the scion, and we observed a low
level of DNA methylation of the CaMV 35S promoter in the scion. Next, wild-type (WT)
tobacco scions were grafted onto RdDM-inducing rootstocks (designated NT) or WT rootstocks
(designated NN), and scion leaves were subjected to multi-omics analyses. Our
transcriptomic analysis detected 55 differentially expressed genes between the NT and NN
samples. A principal component analysis of proteome profiles showed no significant
differences. In the positive and negative modes of LC-ESI-MS and GC-EI-MS analyses, we
found a large overlap between the metabolomic clusters of the NT and NN samples. In
contrast, the negative mode of a LC-ESI-MS analysis showed separation of clusters of NT
and NN metabolites, and we detected 6 peak groups that significantly differed. In
conclusion, we found that grafting onto RdDM-inducing rootstocks caused a low-level
transmission of sRNAs, resulting in limited DNA methylation in the scion. However, the
causal relationships between sRNA transmission and the very slight changes in the
transcriptomic and metabolomic profiles of the scions remains unclear. The safety
assessment points for grafting with RdDM rootstocks are discussed.
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