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Westbrook AS, DiTommaso A. Hybridization in agricultural weeds: A review from ecological, evolutionary, and management perspectives. AMERICAN JOURNAL OF BOTANY 2023; 110:e16258. [PMID: 38031455 DOI: 10.1002/ajb2.16258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 10/22/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023]
Abstract
Agricultural weeds frequently hybridize with each other or with related crop species. Some hybrid weeds exhibit heterosis (hybrid vigor), which may be stabilized through mechanisms like genome duplication or vegetative reproduction. Even when heterosis is not stabilized, hybridization events diversify weed gene pools and often enable adaptive introgression. Consequently, hybridization may promote weed evolution and exacerbate weed-crop competition. However, hybridization does not always increase weediness. Even when viable and fertile, hybrid weeds sometimes prove unsuccessful in crop fields. This review provides an overview of weed hybridization and its management implications. We describe intrinsic and extrinsic factors that influence hybrid fitness in agroecosystems. We also survey the rapidly growing literature on crop-weed hybridization and the link between hybridization and invasiveness. These topics are increasingly relevant in this era of genetic tools for crop improvement, intensive and simplified cropping systems, and globalized trade. The review concludes with suggested research priorities, including hybridization in the context of climate change, plant-insect interactions, and redesigned weed management programs. From a weed management perspective, hybridization is one of many reasons that researchers and land managers must diversify their weed control toolkits.
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Affiliation(s)
- Anna S Westbrook
- Section of Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Antonio DiTommaso
- Section of Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA
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Sohn SI, Thamilarasan SK, Pandian S, Oh YJ, Kang HJ, Shin EK. Characteristics and Fitness Analysis through Interspecific Hybrid Progenies of Transgenic Brassica napus and B. rapa L. ssp. Int J Mol Sci 2022; 23:ijms231810512. [PMID: 36142426 PMCID: PMC9506035 DOI: 10.3390/ijms231810512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/01/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
Interspecific hybridization between transgenic crops and their wild relatives is a major concern for transgene dispersal in the environment. Under controlled conditions, artificial hand pollination experiments were performed in order to assess the hybridization potential and the fitness of interspecific hybrids between Brassica rapa and genetically modified (GM) Brassica napus. Initially, six subspecies of B. rapa were hybridized with GM B. napus through hand pollination. In the resulting F1 hybrids, the combination of B. rapa ssp. narinosa (♀) × GM B. napus (♂) had the highest crossability index (16.9 ± 2.6). However, the F1 selfing progenies of B. rapa ssp. rapa (♀) × GM B. napus were found to be more effective in producing viable future generations with the highest crossability index (1.6 ± 0.69) compared to other subspecies. Consequently, they were used for the generation of F2 and F3 progenies. The 18 different morphological characteristics among the parental cross-combinations and F1 hybrid progenies were measured and visualized through hierarchical clustering. Different generations were found to be grouped based on their different morphological characteristics. The chromosome numbers among the interspecific hybrids ranged from 2n = 29 to 2n = 40. Furthermore, the SSR markers revealed the presence of genomic portions in the hybrids in comparison with their parental lines. There is a high possibility of transgene flow between GM B. napus and B. rapa. The study concluded that the interspecific hybrids between B. napus and B. rapa can be viable and can actively hybridize up to F3 generations and more. This suggests that the GM B. napus can disperse the transgene into B. rapa, and that it can pass through for several generations by hand pollination in a greenhouse environment.
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Affiliation(s)
- Soo-In Sohn
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
- Correspondence: ; Tel.: +82-063-238-4712
| | - Senthil Kumar Thamilarasan
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
| | - Subramani Pandian
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
| | - Young-Ju Oh
- Institute for Future Environment Ecology Co., Ltd., Jeonju 54883, Korea
| | - Hyeon-Jung Kang
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
| | - Eun-Kyoung Shin
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
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Sohn SI, Thamilarasan SK, Pandian S, Oh YJ, Ryu TH, Lee GS, Shin EK. Interspecific Hybridization of Transgenic Brassica napus and Brassica rapa-An Overview. Genes (Basel) 2022; 13:genes13081442. [PMID: 36011353 PMCID: PMC9407623 DOI: 10.3390/genes13081442] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/12/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022] Open
Abstract
In nature, interspecific hybridization occurs frequently and can contribute to the production of new species or the introgression of beneficial adaptive features between species. It has great potential in agricultural systems to boost the process of targeted crop improvement. In the advent of genetically modified (GM) crops, it has a disadvantage that it involves the transgene escaping to unintended plants, which could result in non-specific weedy crops. Several crop species in the Brassica genus have close kinship: canola (Brassica napus) is an ancestral hybrid of B. rapa and B. oleracea and mustard species such as B. juncea, B. carinata, and B. nigra share common genomes. Hence, intraspecific hybridization among the Brassica species is most common, especially between B. napus and B. rapa. In general, interspecific hybrids cause numerous genetic and phenotypic changes in the parental lines. Consequently, their fitness and reproductive ability are also highly varied. In this review, we discuss the interspecific hybridization and reciprocal hybridization studies of B. napus and B. rapa and their potential in the controlled environment. Further, we address the fate of transgenes (herbicide resistance) and their ability to transfer to their progenies or generations. This could help us to understand the environmental influence of interspecific hybrids and how to effectively manage their transgene escape in the future.
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Affiliation(s)
- Soo-In Sohn
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
- Correspondence: ; Tel.: +82-063-238-4712
| | - Senthil Kumar Thamilarasan
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
| | - Subramani Pandian
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
| | - Young-Ju Oh
- Institute for Future Environment Ecology Co., Ltd., Jeonju 54883, Korea
| | - Tae-Hun Ryu
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
| | - Gang-Seob Lee
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
| | - Eun-Kyoung Shin
- Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju 54874, Korea
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Ouyang D, Dong S, Xiao M, You J, Zhao Y, Wang Y, Zhang W, Yang J, Song Z. Compensation of Wild Plants Weakens the Effects of Crop-Wild Gene Flow on Wild Rice Populations. FRONTIERS IN PLANT SCIENCE 2021; 12:681008. [PMID: 34326854 PMCID: PMC8314011 DOI: 10.3389/fpls.2021.681008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/14/2021] [Indexed: 06/13/2023]
Abstract
Crop-wild gene flow may alter the fitness of the recipient i.e., crop-wild hybrids, then potentially impact wild populations, especially for the gene flow carrying selective advantageous crop alleles, such as transgenes conferring insect resistance. Given the continuous crop-wild gene flow since crop domestication and the occasionally stressful environments, the extant wild populations of most crops are still "wild." One interpretation for this phenomenon is that wild populations have the mechanism buffered for the effects of crop alleles. However, solid evidence for this has been scarce. We used wild rice (Oryza rufipogon) and transgenic (Bt/CpTI) rice (O. sativa) as a crop-wild gene flow model and established cultivated, wild, and F7 hybrid rice populations under four levels of insect (Chilo suppressalis) pressure. Then, we measured the trait performance of the plants and estimated fitness to test the compensatory response of relatively high fitness compared to the level of insect damage. The performance of all plants varied with the insect pressure level; wild plants had higher insect-tolerance that was expressed as over- or equal-compensatory responses to insect damage, whereas crop and hybrids exhibited under-compensatory responses. The higher compensation resulted in a better performance of wild rice under insect pressure where transgenes conferring insect resistance had a somewhat beneficial effect. Remarkable hybrid vigour and the benefit effect of transgenes increased the fitness of hybrids together, but this joint effect was weakened by the compensation of wild plants. These results suggest that compensation to environmental stress may reduce the potential impacts of crop alleles on wild plants, thereby it is a mechanism maintaining the "wild" characteristics of wild populations under the scenario of continuous crop-wild gene flow.
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Affiliation(s)
- Dongxin Ouyang
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
| | - Shanshan Dong
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
- Nanjing Institute of Environmental Sciences of the Ministry of Ecology and Environment, Nanjing, China
| | - Manqiu Xiao
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
| | - Jianling You
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
| | - Yao Zhao
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
| | - Yuguo Wang
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
| | - Wenju Zhang
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
| | - Ji Yang
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
| | - Zhiping Song
- The Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Institute of Botany, Tibet University-Fudan University Joint Laboratory for Biodiversity and Global Change, Fudan University, Shanghai, China
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Burgarella C, Barnaud A, Kane NA, Jankowski F, Scarcelli N, Billot C, Vigouroux Y, Berthouly-Salazar C. Adaptive Introgression: An Untapped Evolutionary Mechanism for Crop Adaptation. FRONTIERS IN PLANT SCIENCE 2019; 10:4. [PMID: 30774638 PMCID: PMC6367218 DOI: 10.3389/fpls.2019.00004] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 01/04/2019] [Indexed: 05/18/2023]
Abstract
Global environmental changes strongly impact wild and domesticated species biology and their associated ecosystem services. For crops, global warming has led to significant changes in terms of phenology and/or yield. To respond to the agricultural challenges of this century, there is a strong need for harnessing the genetic variability of crops and adapting them to new conditions. Gene flow, from either the same species or a different species, may be an immediate primary source to widen genetic diversity and adaptions to various environments. When the incorporation of a foreign variant leads to an increase of the fitness of the recipient pool, it is referred to as "adaptive introgression". Crop species are excellent case studies of this phenomenon since their genetic variability has been considerably reduced over space and time but most of them continue exchanging genetic material with their wild relatives. In this paper, we review studies of adaptive introgression, presenting methodological approaches and challenges to detecting it. We pay particular attention to the potential of this evolutionary mechanism for the adaptation of crops. Furthermore, we discuss the importance of farmers' knowledge and practices in shaping wild-to-crop gene flow. Finally, we argue that screening the wild introgression already existing in the cultivated gene pool may be an effective strategy for uncovering wild diversity relevant for crop adaptation to current environmental changes and for informing new breeding directions.
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Affiliation(s)
- Concetta Burgarella
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR AGAP, Montpellier, France
- AGAP, Université de Montpellier, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Institut National de la Recherche Agronomique, Montpellier SupAgro, Montpellier, France
- *Correspondence: Concetta Burgarella, Cécile Berthouly-Salazar,
| | - Adeline Barnaud
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
| | - Ndjido Ardo Kane
- Laboratoire National de Recherches sur les Productions Végétales, Institut Sénégalais de Recherches Agricoles, Dakar, Senegal
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, Dakar, Senegal
| | - Frédérique Jankowski
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UPR GREEN, Montpellier, France
- GREEN, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Université de Montpellier, Montpellier, France
- Bureau d’Analyses Macro-Economiques, Institut Sénégalais de Recherches Agricoles, Dakar, Senegal
| | - Nora Scarcelli
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
| | - Claire Billot
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR AGAP, Montpellier, France
- AGAP, Université de Montpellier, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Institut National de la Recherche Agronomique, Montpellier SupAgro, Montpellier, France
| | - Yves Vigouroux
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
| | - Cécile Berthouly-Salazar
- Institut de Recherche pour le Développement, UMR DIADE, Montpellier, France
- DIADE, Université de Montpellier, Montpellier, France
- Laboratoire Mixte International Adaptation des Plantes et Microorganismes Associés aux Stress Environnementaux, Dakar, Senegal
- *Correspondence: Concetta Burgarella, Cécile Berthouly-Salazar,
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7
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Bigelow PJ, Loescher W, Hancock JF, Grumet R. Influence of intergenotypic competition on multigenerational persistence of abiotic stress resistance transgenes in populations of Arabidopsis thaliana. Evol Appl 2018; 11:950-962. [PMID: 29928302 PMCID: PMC5999209 DOI: 10.1111/eva.12610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 01/29/2018] [Indexed: 12/02/2022] Open
Abstract
Reducing crop losses due to abiotic stresses is a major target of agricultural biotechnology that will increase with climate change and global population growth. Concerns, however, have been raised about potential ecological impacts if transgenes become established in wild populations and cause increased competitiveness of weedy or invasive species. Potential risks will be a function of transgene movement, population sizes, and fitness effects on the recipient population. While key components influencing gene flow have been extensively investigated, there have been few studies on factors subsequent to transgene movement that can influence persistence and competitiveness. Here, we performed multiyear, multigenerational, assessment to examine fitness effects and persistence of three mechanistically different abiotic stress tolerance genes: C-repeat binding factor 3/drought responsive element binding factor 1a (CBF3/DREB1a); Salt overly sensitive 1 (SOS1); and Mannose-6-phosphate reductase (M6PR). Transgenic Arabidopsis thaliana overexpressing these genes were grown in pure populations and in competition with wild-type (WT) parents for six generations spanning a range of field environment conditions. Growth, development, biomass, seed production, and transgene frequency were measured at each generation. Seed planted for each generation was obtained from the previous generation as would occur during establishment of a new genotype in the environment. The three transgenes exhibited different fitness effects and followed different establishment trajectories. In comparison with pure populations, CBF3 lines exhibited reduced dry weight, seed yield, and viable seed yield, relative to WT background. In contrast, overexpression of SOS1 and M6PR did not significantly impact productivity measures in pure populations. In competition with WT, negative fitness effects were magnified. Transgene frequencies were significantly reduced for CBF3 and SOS1 while frequencies of M6PR appeared to be subject to genetic drift. These studies demonstrate the importance of fitness effects and intergenotype competition in influencing persistence of transgenes conferring complex traits.
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Affiliation(s)
- Patrick J. Bigelow
- Graduate Program in Plant Breeding, Genetics and BiotechnologyMichigan State UniversityEast LansingMIUSA
| | - Wayne Loescher
- Graduate Program in Plant Breeding, Genetics and BiotechnologyMichigan State UniversityEast LansingMIUSA
| | - James F. Hancock
- Graduate Program in Plant Breeding, Genetics and BiotechnologyMichigan State UniversityEast LansingMIUSA
| | - Rebecca Grumet
- Graduate Program in Plant Breeding, Genetics and BiotechnologyMichigan State UniversityEast LansingMIUSA
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de Jong TJ, Escobedo Quevedo K, van der Veen-van Wijk CAM, Moshgani M. Performance of aneuploid backcross hybrids between the crop Brassica napus and its wild relative B. rapa. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:67-74. [PMID: 28921773 DOI: 10.1111/plb.12629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 09/13/2017] [Indexed: 06/07/2023]
Abstract
Crossings between the diploid wild Brassica rapa (AA, 2n = 20) and the tetraploid cultivar B. napus (AACC, 2n = 38) can readily be made. Backcrosses to the wild B. rapa (BC1 ) produce aneuploids with variable chromosome numbers between 20 and 29. How does survival and performance relate to DNA content of plants? Growth of the BC1 plants was measured in the lab. One plant in the F1 self-pollinated spontaneously and produced abundant F2 seeds that were also examined. The number of C-chromosomes was estimated from DNA values obtained with flow cytometry. Average DNA value of the BC1 was similar to that of the parents, which shows that C-chromosomes do not reduce success of pollen or embryos. The average DNA value in the F2 was 13% higher than in the F1 , suggesting that extra C-chromosomes facilitated gamete success and/or embryo survival. Under both optimal and drought stress conditions growth and survival of BC1 hybrids was similar to that of B. rapa. No significant correlations existed between growth or survival and DNA value. Aneuploid plants were not inferior under the conditions of the growth room and may persist in nature. We discuss other factors, such as herbivory, that could prevent hybrid establishment in the field.
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Affiliation(s)
- T J de Jong
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands
| | | | | | - M Moshgani
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands
- Department of Environmental Science, Faculty of Agriculture, University of Birjand, Birjand, Iran
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Merotto A, Goulart ICGR, Nunes AL, Kalsing A, Markus C, Menezes VG, Wander AE. Evolutionary and social consequences of introgression of nontransgenic herbicide resistance from rice to weedy rice in Brazil. Evol Appl 2016; 9:837-46. [PMID: 27468302 PMCID: PMC4947146 DOI: 10.1111/eva.12387] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/25/2016] [Indexed: 11/28/2022] Open
Abstract
Several studies have expressed concerns about the effects of gene flow from transgenic herbicide-resistant crops to their wild relatives, but no major problems have been observed. This review describes a case study in which what has been feared in transgenics regarding gene flow has actually changed biodiversity and people's lives. Nontransgenic imidazolinone-resistant rice (IMI-rice) cultivars increased the rice grain yield by 50% in southern Brazil. This increase was beneficial for life quality of the farmers and also improved the regional economy. However, weedy rice resistant to imidazolinone herbicides started to evolve three years after the first use of IMI-rice cultivars. Population genetic studies indicate that the herbicide-resistant weedy rice was mainly originated from gene flow from resistant cultivars and distributed by seed migration. The problems related with herbicide-resistant weedy rice increased the production costs of rice that forced farmers to sell or rent their land. Gene flow from cultivated rice to weedy rice has proven to be a large agricultural, economic, and social constraint in the use of herbicide-resistant technologies in rice. This problem must be taken into account for the development of new transgenic or nontransgenic rice technologies.
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Affiliation(s)
- Aldo Merotto
- Federal University of Rio Grande do Sul-UFRGS Porto Alegre RS Brazil
| | - Ives C G R Goulart
- Brasilian Agriculture Research Corporation-EMBRAPA Forestry Colombo PR Brazil
| | | | | | - Catarine Markus
- Federal University of Rio Grande do Sul-UFRGS Porto Alegre RS Brazil
| | | | - Alcido E Wander
- Brasilian Agriculture Research Corporation-EMBRAPA Rice and Beans Santo Antônio de Goias GO Brazil
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Gressel J. Dealing with transgene flow of crop protection traits from crops to their relatives. PEST MANAGEMENT SCIENCE 2015; 71:658-667. [PMID: 24977384 DOI: 10.1002/ps.3850] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 06/22/2014] [Accepted: 06/24/2014] [Indexed: 06/03/2023]
Abstract
Genes regularly move within species, to/from crops, as well as to their con- specific progenitors, feral and weedy forms ('vertical' gene flow). Genes occasionally move to/from crops and their distantly related, hardly sexually interbreeding relatives, within a genus or among closely related genera (diagonal gene flow). Regulators have singled out transgene flow as an issue, yet non-transgenic herbicide resistance traits pose equal problems, which cannot be mitigated. The risks are quite different from genes flowing to natural (wild) ecosystems versus ruderal and agroecosystems. Transgenic herbicide resistance poses a major risk if introgressed into weedy relatives; disease and insect resistance less so. Technologies have been proposed to contain genes within crops (chloroplast transformation, male sterility) that imperfectly prevent gene flow by pollen to the wild. Containment does not prevent related weeds from pollinating crops. Repeated backcrossing with weeds as pollen parents results in gene establishment in the weeds. Transgenic mitigation relies on coupling crop protection traits in a tandem construct with traits that lower the fitness of the related weeds. Mitigation traits can be morphological (dwarfing, no seed shatter) or chemical (sensitivity to a chemical used later in a rotation). Tandem mitigation traits are genetically linked and will move together. Mitigation traits can also be spread by inserting them in multicopy transposons which disperse faster than the crop protection genes in related weeds. Thus, there are gene flow risks mainly to weeds from some crop protection traits; risks that can and should be dealt with.
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11
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Liu YB, Darmency H, Stewart CN, Wei W, Tang ZX, Ma KP. The effect of Bt-transgene introgression on plant growth and reproduction in wild Brassica juncea. Transgenic Res 2014; 24:537-47. [PMID: 25487040 DOI: 10.1007/s11248-014-9858-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
Abstract
This study aims to investigate the relative plant growth and reproduction of insect-resistant and susceptible plants following the introgression of an insect-resistance Bt-transgene from Brassica napus, oilseed rape, to wild Brassica juncea. The second backcrossed generation (BC2) from a single backcross family was grown in pure and mixed stands of Bt-transgenic and non-transgenic siblings under two insect treatments. Various proportions of Bt-transgenic plants were employed in mixed stands to study the interaction between resistant and susceptible plants. In the pure stands, Bt-transgenic BC2 plants performed better than non-transgenic plants with or without insect treatments. In mixed stands, Bt-transgenic BC2 plants produced fewer seeds than their non-Bt counterparts at low proportions of Bt-transgenic BC2 plants in the absence of insects. Reproductive allocation of non-transgenic plants marginally increased with increasing proportions of Bt-transgenic plants under herbivore pressure, which resulted in increased total biomass and seed production per stand. The results showed that the growth of non-transgenic plants was protected by Bt-transgenic plants under herbivore pressure. The Bt-transgene might not be advantageous in mixed stands of backcrossed hybrids; thus transgene introgression would not be facilitated when herbivorous insects are not present. However, a relatively large initial population of Bt-transgenic plants might result in transgene persistence when target herbivores are present.
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Affiliation(s)
- Yong-Bo Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Beijing, 100093, China
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Gressel J, Levy AA. Use of multicopy transposons bearing unfitness genes in weed control: four example scenarios. PLANT PHYSIOLOGY 2014; 166:1221-31. [PMID: 24820021 PMCID: PMC4226382 DOI: 10.1104/pp.114.236935] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 05/09/2014] [Indexed: 05/09/2023]
Abstract
We speculate that multicopy transposons, carrying both fitness and unfitness genes, can provide new positive and negative selection options to intractable weed problems. Multicopy transposons rapidly disseminate through populations, appearing in approximately 100% of progeny, unlike nuclear transgenes, which appear in a proportion of segregating populations. Different unfitness transgenes and modes of propagation will be appropriate for different cases: (1) outcrossing Amaranthus spp. (that evolved resistances to major herbicides); (2) Lolium spp., important pasture grasses, yet herbicide-resistant weeds in crops; (3) rice (Oryza sativa), often infested with feral weedy rice, which interbreeds with the crop; and (4) self-compatible sorghum (Sorghum bicolor), which readily crosses with conspecific shattercane and with allotetraploid johnsongrass (Sorghum halepense). The speculated outcome of these scenarios is to generate weed populations that contain the unfitness gene and thus are easily controllable. Unfitness genes can be under chemically or environmentally inducible promoters, activated after gene dissemination, or under constitutive promoters where the gene function is utilized only at special times (e.g. sensitivity to an herbicide). The transposons can be vectored to the weeds by introgression from the crop (in rice, sorghum, and Lolium spp.) or from planted engineered weed (Amaranthus spp.) using a gene conferring the degradation of a no longer widely used herbicide, especially in tandem with an herbicide-resistant gene that kills all nonhybrids, facilitating the rapid dissemination of the multicopy transposons in a weedy population.
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Affiliation(s)
- Jonathan Gressel
- Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Avraham A Levy
- Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
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13
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Hartman Y, Hooftman DAP, Uwimana B, Schranz ME, van de Wiel CCM, Smulders MJM, Visser RGF, Michelmore RW, van Tienderen PH. Abiotic stress QTL in lettuce crop-wild hybrids: comparing greenhouse and field experiments. Ecol Evol 2014; 4:2395-409. [PMID: 25360276 PMCID: PMC4203288 DOI: 10.1002/ece3.1060] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 03/03/2014] [Accepted: 03/11/2014] [Indexed: 11/11/2022] Open
Abstract
The development of stress-tolerant crops is an increasingly important goal of current crop breeding. A higher abiotic stress tolerance could increase the probability of introgression of genes from crops to wild relatives. This is particularly relevant to the discussion on the risks of new GM crops that may be engineered to increase abiotic stress resistance. We investigated abiotic stress QTL in greenhouse and field experiments in which we subjected recombinant inbred lines from a cross between cultivated Lactuca sativa cv. Salinas and its wild relative L. serriola to drought, low nutrients, salt stress, and aboveground competition. Aboveground biomass at the end of the rosette stage was used as a proxy for the performance of plants under a particular stress. We detected a mosaic of abiotic stress QTL over the entire genome with little overlap between QTL from different stresses. The two QTL clusters that were identified reflected general growth rather than specific stress responses and colocated with clusters found in earlier studies for leaf shape and flowering time. Genetic correlations across treatments were often higher among different stress treatments within the same experiment (greenhouse or field), than among the same type of stress applied in different experiments. Moreover, the effects of the field stress treatments were more correlated with those of the greenhouse competition treatments than to those of the other greenhouse stress experiments, suggesting that competition rather than abiotic stress is a major factor in the field. In conclusion, the introgression risk of stress tolerance (trans-)genes under field conditions cannot easily be predicted based on genomic background selection patterns from controlled QTL experiments in greenhouses, especially field data will be needed to assess potential (negative) ecological effects of introgression of these transgenes into wild relatives.
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Affiliation(s)
- Yorike Hartman
- Institute for Biodiversity and Ecosystem Dynamics, Universiteit van Amsterdam Amsterdam, The Netherlands
| | - Danny A P Hooftman
- Institute for Biodiversity and Ecosystem Dynamics, Universiteit van Amsterdam Amsterdam, The Netherlands ; NERC, Centre for Ecology and Hydrology Wallingford, UK
| | - Brigitte Uwimana
- Wageningen UR Plant Breeding, Wageningen University and Research Centre Wageningen, The Netherlands
| | - M Eric Schranz
- Institute for Biodiversity and Ecosystem Dynamics, Universiteit van Amsterdam Amsterdam, The Netherlands
| | - Clemens C M van de Wiel
- Wageningen UR Plant Breeding, Wageningen University and Research Centre Wageningen, The Netherlands
| | - Marinus J M Smulders
- Wageningen UR Plant Breeding, Wageningen University and Research Centre Wageningen, The Netherlands
| | - Richard G F Visser
- Wageningen UR Plant Breeding, Wageningen University and Research Centre Wageningen, The Netherlands
| | - Richard W Michelmore
- Genome Center and Department of Plant Sciences, University of California Davis, California
| | - Peter H van Tienderen
- Institute for Biodiversity and Ecosystem Dynamics, Universiteit van Amsterdam Amsterdam, The Netherlands
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14
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Gressel J, van der Vlugt CJB, Bergmans HEN. Cultivated microalgae spills: hard to predict/easier to mitigate risks. Trends Biotechnol 2013; 32:65-9. [PMID: 24369876 DOI: 10.1016/j.tibtech.2013.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 11/03/2013] [Accepted: 11/18/2013] [Indexed: 11/25/2022]
Abstract
Cultivating algae on a large scale will inevitably lead to spills into natural ecosystems. Most risk analyses have dealt only with transgenic algae, without considering the risks of cultivating the corresponding non-transgenic wild type species. This is despite the long-studied 'paradox of the plankton', which describes the unsuitability of laboratory experimentation or modeling to predict the outcome of introducing non-native algae into a new ecosystem. Risk analyses of transgenic strains of native algae can be based on whether they are more fit or less fit than their wild type, but these are not possible with non-native species. Risks from spills can be minimized by mutagenically or transgenically deleting genes that are unnecessary in culture but obligatory in nature.
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Affiliation(s)
- Jonathan Gressel
- Plant Sciences, Weizmann Institute of Science, Rehovot, Israel 76100.
| | - Cécile J B van der Vlugt
- Center for Safety of Substances and Products, National Institute of Public Health and the Environment (RIVM), 3720BA Bilthoven, The Netherlands
| | - Hans E N Bergmans
- Center for Safety of Substances and Products, National Institute of Public Health and the Environment (RIVM), 3720BA Bilthoven, The Netherlands
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15
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Liu Y, Wei W, Ma K, Li J, Liang Y, Darmency H. Consequences of gene flow between oilseed rape (Brassica napus) and its relatives. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 211:42-51. [PMID: 23987810 DOI: 10.1016/j.plantsci.2013.07.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 07/04/2013] [Accepted: 07/06/2013] [Indexed: 06/02/2023]
Abstract
Numerous studies have focused on the probability of occurrence of gene flow between transgenic crops and their wild relatives and the likelihood of transgene escape, which should be assessed before the commercial release of transgenic crops. This review paper focuses on this issue for oilseed rape, Brassica napus L., a species that produces huge numbers of pollen grains and seeds. We analyze separately the distinct steps of gene flow: (1) pollen and seeds as vectors of gene flow; (2) spontaneous hybridization; (3) hybrid behavior, fitness cost due to hybridization and mechanisms of introgression; (4) and fitness benefit due to transgenes (e.g. herbicide resistance and Bt toxin). Some physical, biological and molecular means of transgene containment are also described. Although hybrids and first generation progeny are difficult to identify in fields and non-crop habitats, the literature shows that transgenes could readily introgress into Brassica rapa, Brassica juncea and Brassica oleracea, while introgression is expected to be rare with Brassica nigra, Hirschfeldia incana and Raphanus raphanistrum. The hybrids grow well but produce less seed than their wild parent. The difference declines with increasing generations. However, there is large uncertainty about the evolution of chromosome numbers and recombination, and many parameters of life history traits of hybrids and progeny are not determined with satisfactory confidence to build generic models capable to really cover the wide diversity of situations. We show that more studies are needed to strengthen and organize biological knowledge, which is a necessary prerequisite for model simulations to assess the practical and evolutionary outputs of introgression, and to provide guidelines for gene flow management.
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Affiliation(s)
- Yongbo Liu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China
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16
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17
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Uwimana B, Smulders MJM, Hooftman DAP, Hartman Y, van Tienderen PH, Jansen J, McHale LK, Michelmore RW, van de Wiel CCM, Visser RGF. Hybridization between crops and wild relatives: the contribution of cultivated lettuce to the vigour of crop-wild hybrids under drought, salinity and nutrient deficiency conditions. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2012; 125:1097-111. [PMID: 22660630 PMCID: PMC3442173 DOI: 10.1007/s00122-012-1897-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 05/11/2012] [Indexed: 05/10/2023]
Abstract
With the development of transgenic crop varieties, crop-wild hybridization has received considerable consideration with regard to the potential of transgenes to be transferred to wild species. Although many studies have shown that crops can hybridize with their wild relatives and that the resulting hybrids may show improved fitness over the wild parents, little is still known on the genetic contribution of the crop parent to the performance of the hybrids. In this study, we investigated the vigour of lettuce hybrids using 98 F(2:3) families from a cross between cultivated lettuce and its wild relative Lactuca serriola under non-stress conditions and under drought, salinity and nutrient deficiency. Using single nucleotide polymorphism markers, we mapped quantitative trait loci associated with plant vigour in the F(2:3) families and determined the allelic contribution of the two parents. Seventeen QTLs (quantitative trait loci) associated with vigour and six QTLs associated with the accumulation of ions (Na(+), Cl(-) and K(+)) were mapped on the nine linkage groups of lettuce. Seven of the vigour QTLs had a positive effect from the crop allele and six had a positive effect from the wild allele across treatments, and four QTLs had a positive effect from the crop allele in one treatment and from the wild allele in another treatment. Based on the allelic effect of the QTLs and their location on the genetic map, we could suggest genomic locations where transgene integration should be avoided when aiming at the mitigation of its persistence once crop-wild hybridization takes place.
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Affiliation(s)
| | | | | | - Yorike Hartman
- IBED, Universiteit van Amsterdam, Amsterdam, The Netherlands
| | | | | | - Leah K. McHale
- Department of Horticulture and Crop Science, Ohio State University, Columbus, USA
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18
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Hartman Y, Hooftman DAP, Uwimana B, van de Wiel CCM, Smulders MJM, Visser RGF, van Tienderen PH. Genomic regions in crop-wild hybrids of lettuce are affected differently in different environments: implications for crop breeding. Evol Appl 2012; 5:629-40. [PMID: 23028403 PMCID: PMC3461145 DOI: 10.1111/j.1752-4571.2012.00240.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 12/21/2011] [Indexed: 11/30/2022] Open
Abstract
Many crops contain domestication genes that are generally considered to lower fitness of crop-wild hybrids in the wild environment. Transgenes placed in close linkage with such genes would be less likely to spread into a wild population. Therefore, for environmental risk assessment of GM crops, it is important to know whether genomic regions with such genes exist, and how they affect fitness. We performed quantitative trait loci (QTL) analyses on fitness(-related) traits in two different field environments employing recombinant inbred lines from a cross between cultivated Lactuca sativa and its wild relative Lactuca serriola. We identified a region on linkage group 5 where the crop allele consistently conferred a selective advantage (increasing fitness to 212% and 214%), whereas on linkage group 7, a region conferred a selective disadvantage (reducing fitness to 26% and 5%), mainly through delaying flowering. The probability for a putative transgene spreading would therefore depend strongly on the insertion location. Comparison of these field results with greenhouse data from a previous study using the same lines showed considerable differences in QTL patterns. This indicates that care should be taken when extrapolating experiments from the greenhouse, and that the impact of domestication genes has to be assessed under field conditions.
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Affiliation(s)
- Yorike Hartman
- Institute for Biodiversity and Ecosystem Dynamics, Universiteit van Amsterdam Amsterdam, The Netherlands
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19
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de Jong TJ, Hesse E. Selection against hybrids in mixed populations of Brassica rapa and Brassica napus: model and synthesis. THE NEW PHYTOLOGIST 2012; 194:1134-1142. [PMID: 22463678 DOI: 10.1111/j.1469-8137.2012.04122.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Pollen of the crop oilseed rape (Brassica napus, AACC) can cross-fertilize ovules of Brassica rapa (AA), which leads to an influx of unpaired C-chromosomes into wild B. rapa populations. The presence of such extra chromosomes is thought to be an indicator of introgression. Backcrosses and F(1) hybrids were found in Danish populations but, surprisingly, only F(1) hybrids were found in the UK and the Netherlands. Here, a model tests how the level of selection and biased vs unbiased transmission affect the population frequency of C-chromosomes. In the biased-transmission scenario the experimental results of the first backcross are extrapolated to estimate survival of gametes with different numbers of C-chromosomes from all crosses in the population. With biased transmission, the frequency of C-chromosomes always rapidly declines to zero. With unbiased transmission, the continued presence of plants with extra C-chromosomes depends on selection in the adult stage and we argue that this is the most realistic option for modeling populations. We suggest that selection in the field against plants with unpaired C-chromosomes is strong in Dutch and UK populations. The model highlights what we do not know and makes suggestions for further research on introgression.
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Affiliation(s)
- Tom J de Jong
- Plant Ecology & Phytochemistry, Institute of Biology Leiden, Leiden University, PO Box 9516, 2300RA Leiden, the Netherlands
| | - Elze Hesse
- Plant Ecology & Phytochemistry, Institute of Biology Leiden, Leiden University, PO Box 9516, 2300RA Leiden, the Netherlands
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20
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Londo JP, Bollman MA, Sagers CL, Lee EH, Watrud LS. Changes in fitness-associated traits due to the stacking of transgenic glyphosate resistance and insect resistance in Brassica napus L. Heredity (Edinb) 2011; 107:328-37. [PMID: 21427753 PMCID: PMC3182500 DOI: 10.1038/hdy.2011.19] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 02/05/2011] [Accepted: 02/18/2011] [Indexed: 11/09/2022] Open
Abstract
Increasingly, genetically modified crops are being developed to express multiple 'stacked' traits for different types of transgenes, for example, herbicide resistance, insect resistance, crop quality and tolerance to environmental stresses. The release of crops that express multiple traits could result in ecological changes in weedy environments if feral crop plants or hybrids formed with compatible weeds results in more competitive plants outside of agriculture. To examine the effects of combining transgenes, we developed a stacked line of canola (Brassica napus L.) from a segregating F(2) population that expresses both transgenic glyphosate resistance (CP4 EPSPS) and lepidopteran insect resistance (Cry1Ac). Fitness-associated traits were evaluated between this stacked genotype and five other Brassica genotypes in constructed mesocosm plant communities exposed to insect herbivores (Plutella xylostella L.) or glyphosate-drift. Vegetative biomass, seed production and relative fecundity were all reduced in stacked trait plants when compared with non-transgenic plants in control treatments, indicating potential costs of expressing multiple transgenes without selection pressure. Although costs of the transgenes were offset by selective treatment, the stacked genotype continued to produce fewer seeds than either single transgenic line. However, the increase in fitness of the stacked genotype under selective pressure contributed to an increased number of seeds within the mesocosm community carrying unselected, hitchhiking transgenes. These results demonstrate that the stacking of these transgenes in canola results in fitness costs and benefits that are dependent on the type and strength of selection pressure, and could also contribute to changes in plant communities through hitchhiking of unselected traits.
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Affiliation(s)
- J P Londo
- National Research Council, Corvallis, OR, USA.
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21
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Hooftman DAP, Flavell AJ, Jansen H, den Nijs HCM, Syed NH, Sørensen AP, Orozco-Ter Wengel P, van de Wiel CCM. Locus-dependent selection in crop-wild hybrids of lettuce under field conditions and its implication for GM crop development. Evol Appl 2011; 4:648-59. [PMID: 25568012 PMCID: PMC3352534 DOI: 10.1111/j.1752-4571.2011.00188.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 03/28/2011] [Indexed: 12/01/2022] Open
Abstract
Gene escape from crops has gained much attention in the last two decades, as transgenes introgressing into wild populations could affect the latter's ecological characteristics. However, different genes have different likelihoods of introgression. The mixture of selective forces provided by natural conditions creates an adaptive mosaic of alleles from both parental species. We investigated segregation patterns after hybridization between lettuce (Lactuca sativa) and its wild relative, L. serriola. Three generations of hybrids (S1, BC1, and BC1S1) were grown in habitats mimicking the wild parent's habitat. As control, we harvested S1 seedlings grown under controlled conditions, providing very limited possibility for selection. We used 89 AFLP loci, as well as more recently developed dominant markers, 115 retrotransposon markers (SSAP), and 28 NBS loci linked to resistance genes. For many loci, allele frequencies were biased in plants exposed to natural field conditions, including over-representation of crop alleles for various loci. Furthermore, Linkage disequilibrium was locally changed, allegedly by selection caused by the natural field conditions, providing ample opportunity for genetic hitchhiking. Our study indicates that when developing genetically modified crops, a judicious selection of insertion sites, based on knowledge of selective (dis)advantages of the surrounding crop genome under field conditions, could diminish transgene persistence.
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Affiliation(s)
- Danny A P Hooftman
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam Amsterdam, The Netherlands ; Centre for Ecology and Hydrology Wallingford, UK
| | | | - Hans Jansen
- Biometris Wageningen UR, Wageningen, The Netherlands
| | - Hans C M den Nijs
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam Amsterdam, The Netherlands
| | | | | | - Pablo Orozco-Ter Wengel
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam Amsterdam, The Netherlands ; Keygene N.V Wageningen, The Netherlands
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22
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Kwit C, Moon HS, Warwick SI, Stewart CN. Transgene introgression in crop relatives: molecular evidence and mitigation strategies. Trends Biotechnol 2011; 29:284-93. [PMID: 21388698 DOI: 10.1016/j.tibtech.2011.02.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 01/31/2011] [Accepted: 02/04/2011] [Indexed: 10/18/2022]
Abstract
Incorporation of crop genes into wild and weedy relative populations (i.e. introgression) has long been of interest to ecologists and weed scientists. Potential negative outcomes that result from crop transgene introgression (e.g. extinction of native wild relative populations; invasive spread by wild or weedy hosts) have not been documented, and few examples of transgene introgression exist. However, molecular evidence of introgression from non-transgenic crops to their relatives continues to emerge, even for crops deemed low-risk candidates for transgene introgression. We posit that transgene introgression monitoring and mitigation strategies are warranted in cases in which transgenes are predicted to confer selective advantages and disadvantages to recipient hosts. The utility and consequences of such strategies are examined, and future directions provided.
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Affiliation(s)
- Charles Kwit
- Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA.
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23
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Moon HS, Abercrombie JM, Kausch AP, Stewart CN. Sustainable use of biotechnology for bioenergy feedstocks. ENVIRONMENTAL MANAGEMENT 2010; 46:531-8. [PMID: 20512489 DOI: 10.1007/s00267-010-9503-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 05/07/2010] [Indexed: 05/11/2023]
Abstract
Done correctly, cellulosic bioenergy should be both environmentally and economically beneficial. Carbon sequestration and decreased fossil fuel use are both worthy goals in developing next-generation biofuels. We believe that biotechnology will be needed to significantly improve yield and digestibility of dedicated perennial herbaceous biomass feedstocks, such as switchgrass and Miscanthus, which are native to the US and China, respectively. This Forum discusses the sustainability of herbaceous feedstocks relative to the regulation of biotechnology with regards to likely genetically engineered traits. The Forum focuses on two prominent countries wishing to develop their bioeconomies: the US and China. These two countries also share a political desire and regulatory frameworks to enable the commercialization and wide release of transgenic feedstocks with appropriate and safe new genetics. In recent years, regulators in both countries perform regular inspections of transgenic field releases and seriously consider compliance issues, even though the US framework is considered to be more mature and stringent. Transgene flow continues to be a pertinent environmental and regulatory issue with regards to transgenic plants. This concern is largely driven by consumer issues and ecological uncertainties. Regulators are concerned about large-scale releases of transgenic crops that have sexually compatible crops or wild relatives that can stably harbor transgenes via hybridization and introgression. Therefore, prior to the commercialization or extensive field testing of transgenic bioenergy feedstocks, we recommend that mechanisms that ensure biocontainment of transgenes be instituted, especially for perennial grasses. A cautionary case study will be presented in which a plant's biology and ecology conspired against regulatory constraints in a non-biomass crop perennial grass (creeping bentgrass, Agrostis stolonifera), in which biocontainment was not attained. Appropriate technologies that could be applied to perennial grass feedstocks for biocontainment are discussed.
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Affiliation(s)
- Hong S Moon
- Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA
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