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Nanape AB, Komatsuda T, Kakeda K. Accumulation of mutations in the AP2 homoeologs causes suppression of anther extrusion with altered spike and culm development in hexaploid wheat. MOLECULAR BREEDING : NEW STRATEGIES IN PLANT IMPROVEMENT 2024; 44:19. [PMID: 38404719 PMCID: PMC10884379 DOI: 10.1007/s11032-024-01458-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 02/13/2024] [Indexed: 02/27/2024]
Abstract
Cleistogamy or closed flowering is a widely used trait in barley (Hordeum vulgare) breeding because it reduces the risk of fungal infection in florets at anthesis. Cleistogamy in barley is caused by a point mutation within the microRNA172 (miR172) target site of the Cly1 gene, which encodes the Apetala2 (AP2) transcription factor. Because cleistogamy is not apparent in cultivars of hexaploid wheat (Triticum aestivum), a strategy to develop cleistogamous wheat was proposed by inducing point mutations in all three AP2 homoeologs, which are the wheat orthologs of barley Cly1. In this study, we investigated the effects of miR172 target site mutations on wheat cleistogamy using double mutants by combining three previously obtained mutant alleles (AP2-A1, D1 and D2) in a near-isogenic background. The AP2-D2 allele had the greatest effect on reducing the anther extrusion rate and lodicule size compared with the other two mutant alleles. The double mutant containing the AP2-A1 and AP2-D2 alleles had a much greater suppression of anther extrusion by reducing the lodicule size than the single AP2-D2 mutant, suggesting cumulative effects of the two mutant alleles. In addition, both single and double mutants exhibited compact spikes and shorter plant heights due to reduced rachis and culm internodes in the upper parts. The presence or absence of the wild-type AP2-B homoeolog had no significant effect on phenotype. This study provides insights into the cumulative effects of mutant AP2 alleles in suppressing open flowering and provides a basis for further research on the development of complete cleistogamy in hexaploid wheat. Supplementary Information The online version contains supplementary material available at 10.1007/s11032-024-01458-9.
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Affiliation(s)
- Agetha Bigie Nanape
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 Japan
| | - Takao Komatsuda
- Institute of Crop Science, National Agriculture and Food Research Organization (NARO), 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8518 Japan
- Present Address: Shandong Academy of Agricultural Sciences (SAAS), Crop Research Institute, 202 Gongyebei Road, Licheng District, Jinan, 250100 Shandong China
| | - Katsuyuki Kakeda
- Graduate School of Bioresources, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 Japan
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Huang D, Gao L, McAdams J, Zhao F, Lu H, Wu Y, Martin J, Sherif SM, Subramanian J, Duan H, Liu W. Engineered Cleistogamy in Camelina sativa for bioconfinement. HORTICULTURE RESEARCH 2023; 10:uhac280. [PMID: 36793756 PMCID: PMC9926159 DOI: 10.1093/hr/uhac280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/07/2022] [Indexed: 06/18/2023]
Abstract
Camelina sativa is a self-pollinating and facultative outcrossing oilseed crop. Genetic engineering has been used to improve camelina yield potential for altered fatty acid composition, modified protein profiles, improved seed and oil yield, and enhanced drought resistance. The deployment of transgenic camelina in the field posits high risks related to the introgression of transgenes into non-transgenic camelina and wild relatives. Thus, effective bioconfinement strategies need to be developed to prevent pollen-mediated gene flow (PMGF) from transgenic camelina. In the present study, we overexpressed the cleistogamy (i.e. floral petal non-openness)-inducing PpJAZ1 gene from peach in transgenic camelina. Transgenic camelina overexpressing PpJAZ1 showed three levels of cleistogamy, affected pollen germination rates after anthesis but not during anthesis, and caused a minor silicle abortion only on the main branches. We also conducted field trials to examine the effects of the overexpressed PpJAZ1 on PMGF in the field, and found that the overexpressed PpJAZ1 dramatically inhibited PMGF from transgenic camelina to non-transgenic camelina under the field conditions. Thus, the engineered cleistogamy using the overexpressed PpJAZ1 is a highly effective bioconfinement strategy to limit PMGF from transgenic camelina, and could be used for bioconfinement in other dicot species.
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Affiliation(s)
- Debao Huang
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27607, USA
| | - Liwei Gao
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27607, USA
- College of Life Sciences, Ganzhou Normal University, Ganzhou, Jiangxi 341000, China
| | - Jeremy McAdams
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27607, USA
| | - Fangzhou Zhao
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27607, USA
- National Center for Soybean Improvement, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Hongyan Lu
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27607, USA
- College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan, Hubei 430048, China
| | - Yonghui Wu
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27607, USA
| | - Jeremy Martin
- Sandhills Research Station, North Carolina State University, Jackson Springs, NC 27281, USA
| | - Sherif M Sherif
- Vineland Research Station, Department of Plant Agriculture, University of Guelph, Vinland Station, ON LOR 2E0, Canada
- Alson H. Smith Jr. Agricultural Research and Extension Center, School of Plant and Environmental Sciences, Virginia Tech, Winchester, VA 22602, USA
| | - Jayasankar Subramanian
- Vineland Research Station, Department of Plant Agriculture, University of Guelph, Vinland Station, ON LOR 2E0, Canada
| | - Hui Duan
- Alson H. Smith Jr. Agricultural Research and Extension Center, School of Plant and Environmental Sciences, Virginia Tech, Winchester, VA 22602, USA
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Clark M, Maselko M. Transgene Biocontainment Strategies for Molecular Farming. FRONTIERS IN PLANT SCIENCE 2020; 11:210. [PMID: 32194598 PMCID: PMC7063990 DOI: 10.3389/fpls.2020.00210] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 02/11/2020] [Indexed: 05/21/2023]
Abstract
Advances in plant synthetic biology promise to introduce novel agricultural products in the near future. 'Molecular farms' will include crops engineered to produce medications, vaccines, biofuels, industrial enzymes, and other high value compounds. These crops have the potential to reduce costs while dramatically increasing scales of synthesis and provide new economic opportunities to farmers. Current transgenic crops may be considered safe given their long-standing use, however, some applications of molecular farming may pose risks to human health and the environment. Unwanted gene flow from engineered crops could potentially contaminate the food supply, and affect wildlife. There is also potential for unwanted gene flow into engineered crops which may alter their ability to produce compounds of interest. Here, we briefly discuss the applications of molecular farming and explore the various genetic and physical methods that can be used for transgene biocontainment. As yet, no technology can be applied to all crop species, such that a combination of approaches may be necessary. Effective biocontainment is needed to enable large scale molecular farming.
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Affiliation(s)
- Michael Clark
- Applied Biosciences, Macquarie University, North Ryde, NSW, Australia
| | - Maciej Maselko
- Applied Biosciences, Macquarie University, North Ryde, NSW, Australia
- CSIRO Health and Biosecurity, Canberra, ACT, Australia
- CSIRO Synthetic Biology Future Science Platform, Brisbane, QLD, Australia
- *Correspondence: Maciej Maselko,
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Tang C, Zhang H, Zhang P, Ma Y, Cao M, Hu H, Shah FA, Zhao W, Li M, Wu L. iTRAQ-based quantitative proteome analysis reveals metabolic changes between a cleistogamous wheat mutant and its wild-type wheat counterpart. PeerJ 2019; 7:e7104. [PMID: 31245178 PMCID: PMC6585907 DOI: 10.7717/peerj.7104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 05/08/2019] [Indexed: 11/20/2022] Open
Abstract
Background Wheat is one of the most important staple crops worldwide. Fusarium head blight (FHB) severely affects wheat yield and quality. A novel bread wheat mutant, ZK001, characterized as cleistogamic was isolated from a non-cleistogamous variety Yumai 18 (YM18) through static magnetic field mutagenesis. Cleistogamy is a promising strategy for controlling FHB. However, little is known about the mechanism of cleistogamy in wheat. Methods We performed a FHB resistance test to identify the FHB infection rate of ZK001. We also measured the agronomic traits of ZK001 and the starch and total soluble sugar contents of lodicules in YM18 and ZK001. Finally, we performed comparative studies at the proteome level between YM18 and ZK001 based on the proteomic technique of isobaric tags for relative and absolute quantification. Results The infection rate of ZK001 was lower than that of its wild-type and Aikang 58. The abnormal lodicules of ZK001 lost the ability to push the lemma and palea apart during the flowering stage. Proteome analysis showed that the main differentially abundant proteins (DAPs) were related to carbohydrate metabolism, protein transport, and calcium ion binding. These DAPs may work together to regulate cellular homeostasis, osmotic pressure and the development of lodicules. This hypothesis is supported by the analysis of starch, soluble sugar content in the lodicules as well as the results of Quantitative reverse transcription polymerase chain reaction. Conclusions Proteomic analysis has provided comprehensive information that should be useful for further research on the lodicule development mechanism in wheat. The ZK001 mutant is optimal for studying flower development in wheat and could be very important for FHB resistant projects via conventional crossing.
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Affiliation(s)
- Caiguo Tang
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Huilan Zhang
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Pingping Zhang
- School of Life Sciences, Anhui University, Hefei, Anhui, China
| | - Yuhan Ma
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Minghui Cao
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Hao Hu
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Faheem Afzal Shah
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Weiwei Zhao
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
| | - Minghao Li
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Lifang Wu
- Key laboratory of High Magnetic Field and Ion beam physical biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, China
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Ohmori S, Koike S, Hayashi T, Yamaguchi T, Kuroki M, Yoshida H. The cleistogamy of the superwoman1-cleistogamy1 mutation is sensitive to low temperatures during the lodicule-forming stage. BREEDING SCIENCE 2018; 68:432-441. [PMID: 30369817 PMCID: PMC6198900 DOI: 10.1270/jsbbs.18028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/31/2018] [Indexed: 06/08/2023]
Abstract
We reported previously that the rice (Oryza sativa L.) cleistogamous mutation superwoman1-cleistogamy1 (spw1-cls1) was applicable to inhibit outcrossing between genetically modified varieties and their relatives, which causes pollen-mediated gene flow or disturbance of line purity. The cleistogamy of spw1-cls1 is caused by decreased protein-protein interactions between the mutant SPW1 and its partner proteins. Importantly, these interactions are restored under low-temperature conditions, but whether the cleistogamy of spw1-cls1 is affected by this phenomenon was unclear. In this study, we cultivated spw1-cls1 in various regions of Japan and confirmed that its flowers opened at low temperatures. Moreover, we compared the morphology of a series of lodicules generated at various temperatures. The results indicated that the cleistogamy of spw1-cls1 is thermosensitive and is gradually disturbed as the temperature decreases. This was correlated with the protein interaction pattern of the mutant SPW1 as reported previously. Then, we revealed the critical period for the low-temperature-induced instability of the phenotype of spw1-cls1 and examined the effect of daily temperature changes on cleistogamy. The results may facilitate simulation of the phenotype of spw1-cls1 at various temperatures and the prediction of regions where the cleistogamy of spw1-cls1 can be stably used to inhibit outcrossing.
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Affiliation(s)
- Shinnosuke Ohmori
- Hokuriku Research Center, NARO (National Agriculture and Food Research Organization) Agricultural Research Center,
1-2-1 Inada, Joetsu, Niigata 943-0193,
Japan
| | - Setsuo Koike
- Tohoku Agricultural Research Center, NARO,
4 Akahira, Shimo-kuriyagawa, Morioka, Iwate 020-0198,
Japan
| | - Takami Hayashi
- Tohoku Agricultural Research Center, NARO,
4 Akahira, Shimo-kuriyagawa, Morioka, Iwate 020-0198,
Japan
- Hokkaido Agricultural Research Center, NARO,
1 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8555,
Japan
| | - Tomoya Yamaguchi
- Tohoku Agricultural Research Center, NARO,
4 Akahira, Shimo-kuriyagawa, Morioka, Iwate 020-0198,
Japan
| | - Makoto Kuroki
- Hokkaido Agricultural Research Center, NARO,
1 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8555,
Japan
- Institute of Crop Science, NARO,
2-1-18 Kannondai, Tsukuba, Ibaraki 305-8518,
Japan
| | - Hitoshi Yoshida
- Institute of Crop Science, NARO,
2-1-18 Kannondai, Tsukuba, Ibaraki 305-8518,
Japan
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Schilling S, Pan S, Kennedy A, Melzer R. MADS-box genes and crop domestication: the jack of all traits. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:1447-1469. [PMID: 29474735 DOI: 10.1093/jxb/erx479] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/10/2018] [Indexed: 05/25/2023]
Abstract
MADS-box genes are key regulators of virtually every aspect of plant reproductive development. They play especially prominent roles in flowering time control, inflorescence architecture, floral organ identity determination, and seed development. The developmental and evolutionary importance of MADS-box genes is widely acknowledged. However, their role during flowering plant domestication is less well recognized. Here, we provide an overview illustrating that MADS-box genes have been important targets of selection during crop domestication and improvement. Numerous examples from a diversity of crop plants show that various developmental processes have been shaped by allelic variations in MADS-box genes. We propose that new genomic and genome editing resources provide an excellent starting point for further harnessing the potential of MADS-box genes to improve a variety of reproductive traits in crops. We also suggest that the biophysics of MADS-domain protein-protein and protein-DNA interactions, which is becoming increasingly well characterized, makes them especially suited to exploit coding sequence variations for targeted breeding approaches.
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Affiliation(s)
- Susanne Schilling
- School of Biology and Environmental Science, University College Dublin, Irel
| | - Sirui Pan
- School of Biology and Environmental Science, University College Dublin, Irel
| | - Alice Kennedy
- School of Biology and Environmental Science, University College Dublin, Irel
| | - Rainer Melzer
- School of Biology and Environmental Science, University College Dublin, Irel
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7
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Lombardo F, Kuroki M, Yao S, Shimizu H, Ikegaya T, Kimizu M, Ohmori S, Akiyama T, Hayashi T, Yamaguchi T, Koike S, Yatou O, Yoshida H. The superwoman1-cleistogamy2 mutant is a novel resource for gene containment in rice. PLANT BIOTECHNOLOGY JOURNAL 2017; 15:97-106. [PMID: 27336225 PMCID: PMC5253472 DOI: 10.1111/pbi.12594] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 06/09/2016] [Accepted: 06/18/2016] [Indexed: 05/31/2023]
Abstract
Outcrossing between cultivated plants and their related wild species may result in the loss of favourable agricultural traits in the progeny or escape of transgenes in the environment. Outcrossing can be physically prevented by using cleistogamous (i.e. closed-flower) plants. In rice, flower opening is dependent on the mechanical action of fleshy organs called lodicules, which are generally regarded as the grass petal equivalents. Lodicule identity and development are specified by the action of protein complexes involving the SPW1 and OsMADS2 transcription factors. In the superwoman1-cleistogamy1 (spw1-cls1) mutant, SPW1 is impaired for heterodimerization with OsMADS2 and consequently spw1-cls1 shows thin, ineffective lodicules. However, low temperatures help stabilise the mutated SPW1/OsMADS2 heterodimer and lodicule development is restored when spw1-cls1 is grown in a cold environment, resulting in the loss of the cleistogamous phenotype. To identify a novel, temperature-stable cleistogamous allele of SPW1, targeted and random mutations were introduced into the SPW1 sequence and their effects over SPW1/OsMADS2 dimer formation were assessed in yeast two-hybrid experiments. In parallel, a novel cleistogamous allele of SPW1 called spw1-cls2 was isolated from a forward genetic screen. In spw1-cls2, a mutation leading to a change of an amino acid involved in DNA binding by the transcription factor was identified. Fertility of spw1-cls2 is somewhat decreased under low temperatures but unlike for spw1-cls1, the cleistogamous phenotype is maintained, making the line a safer and valuable genetic resource for gene containment.
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Affiliation(s)
- Fabien Lombardo
- Division of Applied GeneticsInstitute of Agrobiological SciencesNational Agriculture and Food Research Organization (NARO)IbarakiJapan
| | - Makoto Kuroki
- Division of Crop Breeding ResearchHokkaido Agricultural Research CenterNAROHokkaidoJapan
- Division of Rice ResearchInstitute of Crop ScienceNAROIbarakiJapan
| | - Shan‐Guo Yao
- Division of Crop DevelopmentCentral Region Agricultural Research CenterNARONiigataJapan
- Present address: Center for Genome BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing100101China
| | - Hiroyuki Shimizu
- Division of Crop Breeding ResearchHokkaido Agricultural Research CenterNAROHokkaidoJapan
| | - Tomohito Ikegaya
- Division of Crop Breeding ResearchHokkaido Agricultural Research CenterNAROHokkaidoJapan
| | - Mayumi Kimizu
- Division of Crop DevelopmentCentral Region Agricultural Research CenterNARONiigataJapan
| | - Shinnosuke Ohmori
- Division of Crop DevelopmentCentral Region Agricultural Research CenterNARONiigataJapan
| | - Takashi Akiyama
- Division of Applied GeneticsInstitute of Agrobiological SciencesNational Agriculture and Food Research Organization (NARO)IbarakiJapan
| | - Takami Hayashi
- Division of Crop Breeding ResearchHokkaido Agricultural Research CenterNAROHokkaidoJapan
- Division of Agro‐Production Technologies and Management ResearchTohoku Agricultural Research CenterNAROIwateJapan
| | - Tomoya Yamaguchi
- Division of Agro‐Production Technologies and Management ResearchTohoku Agricultural Research CenterNAROIwateJapan
- Present address: Agriculture, Forestry and Fisheries Research CouncilMinistry of Agriculture, Forestry and Fisheries of JapanTokyo100‐8950Japan
| | - Setsuo Koike
- Division of Agro‐Production Technologies and Management ResearchTohoku Agricultural Research CenterNAROIwateJapan
| | - Osamu Yatou
- Division of Crop DevelopmentCentral Region Agricultural Research CenterNARONiigataJapan
| | - Hitoshi Yoshida
- Division of Applied GeneticsInstitute of Agrobiological SciencesNational Agriculture and Food Research Organization (NARO)IbarakiJapan
- Division of Crop DevelopmentCentral Region Agricultural Research CenterNARONiigataJapan
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8
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Abstract
Convincing evidence has accumulated that unintended transgene escape occurs in oilseed rape, maize, cotton and creeping bentgrass. The escaped transgenes are found in variant cultivars, in wild type plants as well as in hybrids of sexually compatible species. The fact that in some cases stacked events are present that have not been planted commercially, implies unintended recombination of transgenic traits. As the consequences of this continuous transgene escape for the ecosystem cannot be reliably predicted, I propose to use more sophisticated approaches of gene technology in future. If possible GM plants should be constructed using either site-directed mutagenesis or cisgenic strategies to avoid the problem of transgene escape. In cases where a transgenic trait is needed, efficient containment should be the standard approach. Various strategies available or in development are discussed. Such a cautious approach in developing novel types of GM crops will enhance the sustainable potential of GM crops and thus increase the public trust in green gene technology.
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Affiliation(s)
- Gerhart U Ryffel
- a Institut für Zellbiologie (Tumorforschung); Universitätsklinikum Essen ; Essen , Germany
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9
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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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