1
|
Itam MO, Iohannes SD, Albertsen M, Andrade M, Bor GA, Atta-Krah K, Bertram R, Danquah E, Horvath DM, Jones T, Mugehu E, Okwuonu I, Ooko-Ombaka A, Roberts RJ, Slamet-Loedin I, Tripathi L, Ubi BE, Varshney RK, Venturi V, Wagaba H, Zeigler R, Creasey Krainer KM. Demonstrating the benefit of agricultural biotechnology in developing countries by bridging the public and private sectors. Nat Plants 2024; 10:2-5. [PMID: 38151530 DOI: 10.1038/s41477-023-01604-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Affiliation(s)
- Michael O Itam
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC, USA
| | | | | | - Maria Andrade
- CIP-Mozambique, International Potato Center, Maputo, Mozambique
| | - Gilbert Arap Bor
- Global Farmer Network, Catholic University of Eastern Africa, Eldoret, Kenya
| | - Kwesi Atta-Krah
- International Institute of Tropical Agriculture, Ibadan, Nigeria
| | - Robert Bertram
- United States Agency for International Development, Washington, DC, USA
| | - Eric Danquah
- West African Center for Crop Improvement, University of Ghana, Accra, Ghana
| | | | | | | | - Ihuoma Okwuonu
- National Root Crops Research Institute, Umudike, Nigeria
| | | | | | | | - Leena Tripathi
- International Institute of Tropical Agriculture, Dar es Salaam, Tanzania
| | | | - Rajeev K Varshney
- WA State Agricultural Biotechnology Centre, Centre for Crop & Food Innovation, Food Futures Institute, Murdoch University, Murdoch, Western Australia, Australia
| | - Vittorio Venturi
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Henry Wagaba
- National Agricultural Research Organisation, Kampala, Uganda
| | | | | |
Collapse
|
2
|
Shantharaj D, Minsavage GV, Orbović V, Moore GA, Holmes DR, Römer P, Horvath DM, Lahaye T, Jones JB. A promoter trap in transgenic citrus mediates recognition of a broad spectrum of Xanthomonas citri pv. citri TALEs, including in planta-evolved derivatives. Plant Biotechnol J 2023; 21:2019-2032. [PMID: 37421233 PMCID: PMC10502743 DOI: 10.1111/pbi.14109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 07/10/2023]
Abstract
Citrus bacterial canker (CBC), caused by Xanthomonas citri subsp. citri (Xcc), causes dramatic losses to the citrus industry worldwide. Transcription activator-like effectors (TALEs), which bind to effector binding elements (EBEs) in host promoters and activate transcription of downstream host genes, contribute significantly to Xcc virulence. The discovery of the biochemical context for the binding of TALEs to matching EBE motifs, an interaction commonly referred to as the TALE code, enabled the in silico prediction of EBEs for each TALE protein. Using the TALE code, we engineered a synthetic resistance (R) gene, called the Xcc-TALE-trap, in which 14 tandemly arranged EBEs, each capable of autonomously recognizing a particular Xcc TALE, drive the expression of Xanthomonas avrGf2, which encodes a bacterial effector that induces plant cell death. Analysis of a corresponding transgenic Duncan grapefruit showed that transcription of the cell death-inducing executor gene, avrGf2, was strictly TALE-dependent and could be activated by several different Xcc TALE proteins. Evaluation of Xcc strains from different continents showed that the Xcc-TALE-trap mediates resistance to this global panel of Xcc isolates. We also studied in planta-evolved TALEs (eTALEs) with novel DNA-binding domains and found that these eTALEs also activate the Xcc-TALE-trap, suggesting that the Xcc-TALE-trap is likely to confer durable resistance to Xcc. Finally, we show that the Xcc-TALE-trap confers resistance not only in laboratory infection assays but also in more agriculturally relevant field studies. In conclusion, transgenic plants containing the Xcc-TALE-trap offer a promising sustainable approach to control CBC.
Collapse
Affiliation(s)
| | | | - Vladimir Orbović
- Citrus Research and Education CenterUniversity of FloridaLake AlfredFLUSA
| | - Gloria A. Moore
- Department of Horticultural SciencesUniversity of FloridaGainesvilleFLUSA
| | - Danalyn R. Holmes
- Zentrum für Molekularbiologie der Pflanzen (ZMBP)Eberhard‐Karls‐Universität TübingenTübingenGermany
| | - Patrick Römer
- Genetics, Department of BiologyLudwig‐Maximilians‐University MunichMartinsriedGermany
- Present address:
Avicare+KöthenGermany
| | | | - Thomas Lahaye
- Zentrum für Molekularbiologie der Pflanzen (ZMBP)Eberhard‐Karls‐Universität TübingenTübingenGermany
- Genetics, Department of BiologyLudwig‐Maximilians‐University MunichMartinsriedGermany
| | | |
Collapse
|
3
|
Shantharaj D, Römer P, Figueiredo JFL, Minsavage GV, Krönauer C, Stall RE, Moore GA, Fisher LC, Hu Y, Horvath DM, Lahaye T, Jones JB. An engineered promoter driving expression of a microbial avirulence gene confers recognition of TAL effectors and reduces growth of diverse Xanthomonas strains in citrus. Mol Plant Pathol 2017; 18:976-989. [PMID: 27362693 PMCID: PMC6638256 DOI: 10.1111/mpp.12454] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/13/2016] [Accepted: 06/27/2016] [Indexed: 05/19/2023]
Abstract
Xanthomonas citri ssp. citri (X. citri), causal agent of citrus canker, uses transcription activator-like effectors (TALEs) as major pathogenicity factors. TALEs, which are delivered into plant cells through the type III secretion system (T3SS), interact with effector binding elements (EBEs) in host genomes to activate the expression of downstream susceptibility genes to promote disease. Predictably, TALEs bind EBEs in host promoters via known combinations of TALE amino acids to DNA bases, known as the TALE code. We introduced 14 EBEs, matching distinct X. citri TALEs, into the promoter of the pepper Bs3 gene (ProBs31EBE ), and fused this engineered promoter with multiple EBEs (ProBs314EBE ) to either the β-glucuronidase (GUS) reporter gene or the coding sequence (cds) of the pepper gene, Bs3. TALE-induced expression of the Bs3 cds in citrus leaves resulted in no visible hypersensitive response (HR). Therefore, we utilized a different approach in which ProBs31EBE and ProBs314EBE were fused to the Xanthomonas gene, avrGf1, which encodes a bacterial effector that elicits an HR in grapefruit and sweet orange. We demonstrated, in transient assays, that activation of ProBs314EBE by X. citri TALEs is T3SS dependent, and that the expression of AvrGf1 triggers HR and correlates with reduced bacterial growth. We further demonstrated that all tested virulent X. citri strains from diverse geographical locations activate ProBs314EBE . TALEs are essential for the virulence of X. citri strains and, because the engineered promoter traps are activated by multiple TALEs, this concept has the potential to confer broad-spectrum, durable resistance to citrus canker in stably transformed plants.
Collapse
Affiliation(s)
- Deepak Shantharaj
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
| | - Patrick Römer
- Genetics, Department of Biology, Ludwig‐Maximilians‐University MunichMartinsriedD‐82152Germany
- Present address:
Nomad Bioscience GmbH, Biozentrum Halle Weinbergweg 22 D‐06120 Halle (Saale)
| | | | | | - Christina Krönauer
- Zentrum für Molekularbiologie der Pflanzen (ZMBP)Eberhard‐Karls‐Universität TübingenAuf der Morgenstelle 32TübingenD‐72076Germany
| | - Robert E. Stall
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
| | - Gloria A. Moore
- Department of Horticultural SciencesUniversity of FloridaGainesvilleFL 32611USA
| | - Latanya C. Fisher
- Department of Horticultural SciencesUniversity of FloridaGainesvilleFL 32611USA
| | - Yang Hu
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
| | - Diana M. Horvath
- 2Blades Foundation, Suite 19011630 Chicago AvenueEvanstonIL60201USA
| | - Thomas Lahaye
- Genetics, Department of Biology, Ludwig‐Maximilians‐University MunichMartinsriedD‐82152Germany
- Zentrum für Molekularbiologie der Pflanzen (ZMBP)Eberhard‐Karls‐Universität TübingenAuf der Morgenstelle 32TübingenD‐72076Germany
| | - Jeffrey B. Jones
- Plant Pathology DepartmentUniversity of FloridaGainesvilleFL 32611USA
| |
Collapse
|
4
|
Abstract
Diverse and rapidly evolving pathogens cause plant diseases and epidemics that threaten crop yield and food security around the world. Research over the last 25 years has led to an increasingly clear conceptual understanding of the molecular components of the plant immune system. Combined with ever-cheaper DNA-sequencing technology and the rich diversity of germ plasm manipulated for over a century by plant breeders, we now have the means to begin development of durable (long-lasting) disease resistance beyond the limits imposed by conventional breeding and in a manner that will replace costly and unsustainable chemical controls.
Collapse
Affiliation(s)
- Jeffery L Dangl
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
| | | | | |
Collapse
|
5
|
Abstract
Transcription activator-like (TAL) effectors are encoded by plant-pathogenic bacteria and induce expression of plant host genes. TAL effectors bind DNA on the basis of a unique code that specifies binding of amino acid residues in repeat units to particular DNA bases in a one-to-one correspondence. This code can be used to predict binding sites of natural TAL effectors and to design novel synthetic DNA-binding domains for targeted genome manipulation. Natural mechanisms of resistance in plants against TAL effector-containing pathogens have given insights into new strategies for disease control.
Collapse
Affiliation(s)
- Sebastian Schornack
- Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, United Kingdom
| | | | | | | |
Collapse
|
6
|
Horvath DM, Stall RE, Jones JB, Pauly MH, Vallad GE, Dahlbeck D, Staskawicz BJ, Scott JW. Transgenic resistance confers effective field level control of bacterial spot disease in tomato. PLoS One 2012; 7:e42036. [PMID: 22870280 PMCID: PMC3411616 DOI: 10.1371/journal.pone.0042036] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 06/29/2012] [Indexed: 12/03/2022] Open
Abstract
We investigated whether lines of transgenic tomato (Solanum lycopersicum) expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides.
Collapse
Affiliation(s)
- Diana M Horvath
- Two Blades Foundation, Evanston, Illinois, United States of America.
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Wulff BBH, Horvath DM, Ward ER. Improving immunity in crops: new tactics in an old game. Curr Opin Plant Biol 2011; 14:468-76. [PMID: 21531167 DOI: 10.1016/j.pbi.2011.04.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 03/18/2011] [Accepted: 04/05/2011] [Indexed: 05/20/2023]
Abstract
Crop disease remains a major cause of yield loss and emerging diseases pose new threats to global food security. Despite the dearth of commercial development to date, progress in using our rapidly expanding knowledge of plant-pathogen interactions to invent new ways of controlling diseases in crops has been good. Many major resistance genes have now been shown to retain function when transferred between species, and evidence indicates that resistance genes are more effective when deployed in a background containing quantitative resistance traits. The EFR pattern-recognition receptor, present in only the Brassicaceae, functions to provide bacterial disease control in the Solanaceae. Knowledge of how transcription activator-like effectors bind DNA is leading to new methods for triggering disease resistance and broader applications in genome engineering.
Collapse
MESH Headings
- Cloning, Molecular
- Crops, Agricultural/genetics
- Crops, Agricultural/immunology
- Crops, Agricultural/microbiology
- Crops, Agricultural/virology
- Disease Resistance
- Gene Expression Regulation, Plant
- Genes, Plant
- Host-Pathogen Interactions
- Plant Diseases/immunology
- Plant Diseases/microbiology
- Plant Diseases/prevention & control
- Plant Diseases/virology
- Plant Immunity
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/immunology
- Plants, Genetically Modified/microbiology
- Plants, Genetically Modified/virology
- Receptors, Pattern Recognition/immunology
- Receptors, Pattern Recognition/metabolism
- Transcriptional Activation
- Transgenes
Collapse
Affiliation(s)
- Brande B H Wulff
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, United Kingdom.
| | | | | |
Collapse
|
8
|
Abstract
We have identified and characterized fragments of 15 salicylic acid (SA) early response genes. The kinetics of induction and response to cycloheximide (CHX) treatment allowed classification of genes into four groups. Classes I-III are characterized by immediate-early responses, showing increased accumulation of mRNA within 30 min of SA treatment. Moreover, CHX did not block induction of these genes, indicating that latent cellular factors mediate the SA response. Class IV genes were induced more slowly, but still within 2 to 3 h of SA treatment, and required protein synthesis for expression. Although identified in this study as SA-responsive genes, several could also be induced by other compounds. Two genes were characterized in more detail, including isolation of cDNA sequences and additional analysis of gene expression. Sequence analysis revealed that the class I gene, C18-1, is the previously identified ethylene response element binding protein 1 (EREBP1), an ethylene-induced transcription factor for basic pathogenesis-related (PR) genes, whereas the class III gene, G8-1, is a novel sequence. G8-1 was found to be strongly induced only by SA and its active analogs and was exquisitely sensitive to low SA concentrations. These and other genes were found to be activated at early times following tobacco mosaic virus infection of resistant tobacco genotypes.
Collapse
Affiliation(s)
- D M Horvath
- Laboratory of Plant Molecular Biology, Rockefeller University, New York, NY 10021 USA.
| | | | | |
Collapse
|
9
|
Horvath DM, Chua NH. Identification of an immediate-early salicylic acid-inducible tobacco gene and characterization of induction by other compounds. Plant Mol Biol 1996; 31:1061-72. [PMID: 8843948 DOI: 10.1007/bf00040724] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Tobacco genes that are induced in response to salicylic acid (SA) treatment with immediate-early kinetics were identified by differential mRNA display. Detailed analysis of IS10a, one cDNA clone identified by this method, revealed induction within 30 min of treatment, with a peak of expression at 3 h, that decayed rapidly thereafter. Treatment with the protein synthesis inhibitor, cycloheximide (CHX), also caused induction of IS10a mRNA to comparable levels, but the IS10a mRNA continued to accumulate after 3 h of induction. In combination, CHX and SA led to a superinduction of IS10a mRNA levels that was also sustained. Half-maximal induction was evident at ca. 100-150 microM SA. In addition to SA, induction of IS10a occurred to varying degrees upon treatment with acetylsalicylic acid, benzoic acid, 2,4-dichlorophenoxyacetic acid, methyl jasmonate, and hydrogen peroxide, whereas treatment with other compounds had no effect. The proteins encoded by IS10a and a second highly homologous cDNA show sequence similarity to UDP-glucose: flavonoid glucosyltransferases.
Collapse
Affiliation(s)
- D M Horvath
- Laboratory of Plant Molecular Biology, Rockefeller University, New York, NY 10021, USA
| | | |
Collapse
|
10
|
Qin XF, Holuigue L, Horvath DM, Chua NH. Immediate early transcription activation by salicylic acid via the cauliflower mosaic virus as-1 element. Plant Cell 1994; 6:863-74. [PMID: 8061520 PMCID: PMC160484 DOI: 10.1105/tpc.6.6.863] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Transgenic tobacco plants carrying a number of regulatory sequences derived from the cauliflower mosaic virus 35S promoter were tested for their response to treatment with salicylic acid (SA), an endogenous signal involved in plant defense responses. beta-Glucuronidase (GUS) gene fusions with the full-length (-343 to +8) 35S promoter or the -90 truncation were found to be induced by SA. Time course experiments revealed that, in the continuous presence of SA, the -90 promoter construct (-90 35S-GUS) displayed rapid and transient induction kinetics, with maximum RNA levels at 1 to 4 hr, which declined to low levels by 24 hr. Induction was still apparent in the presence of the protein synthesis inhibitor cycloheximide (CHX). Moreover, mRNA levels continued to accumulate over 24 hr rather than to decline. By contrast, mRNA from the endogenous pathogenesis-related protein-1a (PR-1a) gene began to accumulate at later times during SA treatment and steadily increased through 24 hr; transcription of this gene was almost completely blocked by the presence of CHX. Further dissection of the region from -90 and -46 of the 35S promoter revealed that the SA-responsive element corresponds to the previously characterized activation sequence-1 (as-1). These results represent a definitive analysis of immediate early responses to SA, relative to the late induction of PR genes, and potentially elucidate the early events of SA signal transduction during the plant defense response.
Collapse
Affiliation(s)
- X F Qin
- Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021-6399
| | | | | | | |
Collapse
|
11
|
Qin XF, Holuigue L, Horvath DM, Chua NH. Immediate early transcription activation by salicylic acid via the cauliflower mosaic virus as-1 element. Plant Cell 1994. [PMID: 8061520 DOI: 10.2307/3869964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Transgenic tobacco plants carrying a number of regulatory sequences derived from the cauliflower mosaic virus 35S promoter were tested for their response to treatment with salicylic acid (SA), an endogenous signal involved in plant defense responses. beta-Glucuronidase (GUS) gene fusions with the full-length (-343 to +8) 35S promoter or the -90 truncation were found to be induced by SA. Time course experiments revealed that, in the continuous presence of SA, the -90 promoter construct (-90 35S-GUS) displayed rapid and transient induction kinetics, with maximum RNA levels at 1 to 4 hr, which declined to low levels by 24 hr. Induction was still apparent in the presence of the protein synthesis inhibitor cycloheximide (CHX). Moreover, mRNA levels continued to accumulate over 24 hr rather than to decline. By contrast, mRNA from the endogenous pathogenesis-related protein-1a (PR-1a) gene began to accumulate at later times during SA treatment and steadily increased through 24 hr; transcription of this gene was almost completely blocked by the presence of CHX. Further dissection of the region from -90 and -46 of the 35S promoter revealed that the SA-responsive element corresponds to the previously characterized activation sequence-1 (as-1). These results represent a definitive analysis of immediate early responses to SA, relative to the late induction of PR genes, and potentially elucidate the early events of SA signal transduction during the plant defense response.
Collapse
Affiliation(s)
- X F Qin
- Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021-6399
| | | | | | | |
Collapse
|
12
|
|