
Rice is an important cereal crop in the world, providing food for nearly half of the world's population. Therefore, rice production is of great significance in ensuring food security and solving basic nutrition problems in the world, especially in developing countries. China is the world's largest rice producer and consumer. According to data provided by the National Bureau of Statistics of China (NBSC), the total area of rice planted in China in 2007 was 439 million mu and the total output was about 182.57 billion kg. On average, China needs to consume 170 billion kilograms of rice each year, accounting for 35.7% of China's total grain output. Rice production and variety improvement in China have gone through different development stages with distinct characteristics, namely traditional systematic selection, genetic improvement breeding, and heterosis through sexual hybridization. At the same time, the application and promotion of these new technologies have played a huge role in the improvement and production of rice varieties. The rapid development of new technologies such as biotechnology, molecular marker-assisted breeding, high throughput molecular testing, and genomics and their application in the agricultural field have brought new opportunities for further genetic improvement of rice varieties and production. Determination of the whole genome DNA sequence of rice has also rapidly promoted research on genetic resources of cultivated rice and
In the current severe situation of the world’s growing population, increasingly insufficient water resources, and gradual reduction of rural labor, the yield per unit area of rice has been continuously increased through continuous development and use of high-tech science and technology. In particular, the transgenic technology provides sufficient guarantee for the continuous high yield of rice and the continuous improvement of varieties. The rapid development of genetically modified biotechnology has played an epoch-making role in the genetic improvement of Chinese rice varieties. China has conducted a lot of exploration and research in the cultivation of genetically modified rice. At present, a large number of genetically modified rice with resistance to insects, diseases, herbicides, and other excellent quality traits have been cultivated (Huang
Since Darwin proposed the theory of species origin and natural selection in 1859, the formation and maintenance mechanism of many biodiversity in nature have been the focus of attention and research of biologists. Factors such as gene flow, natural selection, local adaptation, genetic bottleneck, and genetic drift can affect and change the process of biological diversification from different aspects. In particular, gene flow has attracted much attention because of its dynamic changes on different time and space scales and its influence on the process of biological adaptive evolution and diversification in many ways. Gene flow can be broadly defined as the transfer and exchange of genetic material within and between biological species. Based on this broad definition, the movement of genes, the movement of individuals, and the extinction-reconstruc-tion dynamics in the population are collectively referred to as gene flow (Slatkin 1985). Traditional concept believes that the main function of gene flow is to maintain species cohesion and prevent local adaptation or genetic drift from causing population differentiation. At the same time, gene flow between species can erode the integrity of species genome and hinder the process of biological diversi-fication. Thus, gene flow not only cannot effectively promote biological evolution and species diversification, but also has negative effects. However, with accumulation of more and more experimental data and the development of theoretical simulation research, this traditional concept is being challenged. Relevant studies have gradually shown that gene flow plays an important role in the genetic differentiation and diversification of natural species. It also has a positive impact on speciation and adaptive evolution (Seehausen 2004; Garant
This article aims to conduct a rational analysis of research on pollen mobility of GM rice in China and the current progress and status quo of commercialization of GM rice in China, hoping to provide a reference for safety evaluation and commercialization of GM rice and other crops in Korea.
Research, development, and commercialization of GM rice will provide new opportunities for improving rice productivity and alleviating the global food crisis. However, large-scale environmental release and commer-cial production of GM rice may bring certain environ-mental biosafety issues. Improper handling might affect further research and development of GM rice. Common environmental biosafety issues mainly include the following aspects: (1) The impact and effect of transgenic resistance to biological stress on non-target organisms; (2) The escape of foreign genes to non-transgenic crops and wild relatives with possible ecological consequences; (3) The potential impact of genetically modified crops on agricultural ecosystems, soil microorganisms, and biodi-ver-sity; and (4) The long-term use of bio-stress-resistant transgenes might cause target organisms to develop resistance to transgenes.
Safety research of genetically modified crops is divided into two stages. The first stage is the laboratory stage. Physiological and physical characteristics of genetically edited crops are monitored in a closed laboratory environment and their biological safety is evaluated and researched. The second step is the experimental field cultivation stage, where the gene flow (pollen mobility) of genetically modified crops in an open ecological environment is monitored and related biosafety research is conducted. These two stages are aimed at whether the spread of pollen in the field environment will have a destructive effect on the surrounding ecological environ-ment, animals, and plants during the commercial planting of genetically modified rice.
In the study of Lu
Gene flow between biological natural communities not only can prevent genetic differentiation to maintain the integrity of species, but also can actively respond to the process of biological diversification. Understanding the adaptive evolution related to gene flow and its internal mechanism will help us better understand the true reasons for the formation of biological species and the original dynamics of their diversification.
Through a comprehensive analysis of a series of recent theoretical methods and research progress, it can be seen that ecological environmental factors play a very important role in the process of population fitness, local adaptation, and diversification of species directly or indirectly related to gene flow. The birth of biological species and the formation of biological diversity both involve the interaction of biological genetics and ecological environment. In the process of adaptive evolution and diversification related to gene flow, the dispersal of pollen and seeds, the migration, diffusion, and hybridization of individuals, and other vegetative propagules are constantly transmitting and exchanging genetic information. At the same time, new or changing ecological and environmental factors (such as climate, resources, soil, hydrology and geographic structure, etc.) provide new selection pressures and opportunities for adaptive evolution for these different genetic sources. If gene flow within and between species can actively respond to complex ecological environmental factors, the selection pressure, and driving force of ecological diversity, it will be beneficial to promote adaptive evolution and diversification of species in a shorter period of time. Therefore, when discussing the positive impact of gene flow on adaptive evolution, we must fully consider the role of ecological and environ-mental factors.
Based on the characteristics of plant gene drift and the influence of natural environmental factors. Gene transfer verification methods are divided into four types (Table 1): (1) by the studying of pollen migration range, (2) by the studying of hybrid compatibility between cultivated species and wild species, (3) by verifying gene mobility by using specific morphological features or specific genetic markers to check the outcrossing rate between cultivated varieties and wild species, and. (4) by using specific markers of transgenic plants to determine verify the gene transfer rates of foreign genes to parents or wild species (Liu and Huang. 2009).
Table 1 . Case study of intra and inter-specific gene flow and adaptive evolution in plants (Liu and Huang 2009).
Variety | Research direction | Gene flow dynamics and diversity patterns | The mechanism of gene flow promoting adaptive evolution | References |
---|---|---|---|---|
Intraspecies | Unidirectional linear migration and higher genetic differentiation among populations | Under the condition of unidirectional linear gene flow, the changeable ecological environment of canyons and rivers promotes the continuous establishment and genetic diversification of new populations downstream | Liu | |
Between subspecies within the species | Common origin and free mating, but adapt to different ecological environments | Niche theory: Introgressive hybridization promotes newly formed individuals or populations to adapt to marginal habitats | Choler | |
Intraspecies | The three dwarf-growing populations and their neighboring high-growing individuals formed genetic differentiation, and they had their own independent origins. | Eucalyptus marginal small populations establish genetic differentiation with neighboring large populations through ecological speciation | Foster | |
Intraspecies differentiation to interspecies | Habitat, reproduction and molecular data, as well as recent theoretical simulation analysis, show that there is no strict geographical isolation and gene flow blockage in the same region of genetic differentiation and speciation | The new island soil types produce new island habitats, and ultimately lead to the original population individuals adapting to the new ecological environment under the effect of selection | Savolainen | |
Intraspecies | Morphology, allozyme and cpDNA data reveal that | The uplift of the plateau creates new ecological adaptation environments and opportunities for the offspring of heterozygotes | Wang | |
Species complex | The different gene flows that accompanied the expansion of primitive populations eventually led to the divergence of the two species branches | Natural selection based on different habitats, different ecological and climatic factors, etc. may jointly lead to the final genetic differentiation of the species complex | Friar | |
Intraspecies | The offspring of three sunflower hybrids with different morphologies and adapted to different extreme habitats independently originated from the same pair of ancestral parents | The ecological environment has played an important role in the ecological adaptation, transformation and adaptive evolution of the offspring of these three different heterozygotes. | Gross |
Regarding research on hybrid compatibility between different varieties of plants that may be caused by mobility of GM rice pollen, Chinese researchers have used reproductive biology methods to test cross-compatibility of transgenic rice varieties Y0003 and 99-t (male parent) with rice-associated weed barnyard grass (female parent). The germination and growth of rice pollen on the barnyard grass stigma were observed through an optical microscope at 30 minnutes and 1-4 hours after hand-crossing of barnyard grass with transgenic rice and compared with pollen germination and growth at the corresponding time after barnyard grass flowered (Fig. 1). Their results showed that pollen germination and growth of the two GM rice varieties on the barnyard grass stigma were similar. After barnyard grass self-pollination, pollen grains could germinate and grow normally. At 30 minutes, 85% of pollen grains and pollen tubes could pass through the stigma. At the same time, the content is being condensed and released, or the percentage of pollen grains released by the content gradually increases. After hybridization, the pollen of transgenic rice could not germinate or grow normally on the barnyard grass stigma. It failed to pass through the barnyard grass stigma. Therefore, the incompatibility between barnyard grass and transgenic rice is demonstrated in that rice pollen cannot grow normally on the barnyard grass stigma, let alone pass through the barnyard grass stigma. Results of mating between emasculated barnyard grass and GM rice pollen without setting seeds also proved the incompatibility of these two population (Song
Chinese scholars have also used the same method to study the compatibility between medicinal wild rice and GM rice (Fig. 2 and Fig. 3). Their results showed that the germination and growth of the tested rice pollen on the stigma of the medicinal wild rice were different from those of self-pollinated pollen of the medicinal wild rice. The percentage of pollen grains passing through the stigma and the percentage of pollen grains released by shrinkage are both less than the self-pollination efficiency of wild rice. Although genetically modified rice pollen could normally germinate and grow on the stigma of wild medicinal rice and release its contents, the seed setting rate after hybridization was 0, indicating the incompatibility of hybridization between GM rice and medicinal wild rice (Song
Based on these results, Chinese scholars have used fluorescence microscopy to observe the germination of transgenic rice pollen on the stigma of medicinal wild rice and the growth process in the style to clarify the stage of incompatibility between the two population (Fig. 4). Their results showed that pollen germination rates of the two GM cultivated rice (Y003 and 99t) on the stigma of the medicinal wild rice were lower than those of self-pollinated medicinal wild rice. The pollen tube grew slowly in the style. It stopped growing when it reached the middle of the style (Y003) or the base of the style (99t). Its top was abnormally enlarged. The hybrid ovary gradually shrank and the seed setting rate was 0. Therefore, the reason for the incompatibility between wild medicinal rice and GM cultivated rice was because the pollen tube stopped growing in the style, making it impossible to enter the embryo sac to complete fertilization (Liu
The cross affinity between various plant varieties and target varieties of GM cultivated rice is a prerequisite for successful transfer of foreign genes. Exogenous genes can only achieve gene transfer and reproduction after successful hybridization with other varieties of plants through migration characteristics of pollen (Song
Song
Table 2 . The pollen drift distance and gene flow percentage of transgenic rice (Xiao 2004).
Transgenic rice | Distance (m) | Gene flow percentage (%) | |||||||
---|---|---|---|---|---|---|---|---|---|
East | West | South | North | SE | NE | SW | NW | ||
Bar68-1 (4 m2) | 0 | 1.911 | 4.518 | 1.191 | 4.205 | 1.974 | 2.724 | 1.48 | 0.89 |
1 | 0.138 | 0.237 | 0.077 | 0.216 | 0.496 | 0.406 | 0.765 | 0.23 | |
2 | 0 | 0.253 | 1.058 | 0.21 | 0.33 | 0.056 | 0.332 | 0.038 | |
3 | 0 | 0 | 0.123 | 0 | 0.101 | 0 | 0.356 | 0 | |
4 | 0 | 0.034 | 0 | 0 | 0.073 | 0 | 0.034 | 0 | |
5 | 0 | 0.043 | 0.046 | 0 | 0.116 | 0 | 0.052 | 0 | |
6 | 0.037 | 0 | 0.154 | 0.038 | 0 | 0 | 0 | 0 | |
7 | 0 | 0 | 0.133 | 0 | 0 | 0 | 0.076 | 0 | |
8 | 0 | 0 | 0 | 0 | 0 | 0 | 0.036 | 0 | |
9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
… | … | … | … | … | … | … | … | … | |
14 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Xiang 125S/Bar68-1 (667 m2) | 0 | 0.275 | 0.103 | 0.288 | 0.108 | 0.065 | 0 | 0 | 0.122 |
5 | 0.083 | 0 | 0.257 | 0 | 0 | 0 | 0 | 0.089 | |
10 | 0.134 | 0 | 0.236 | 0 | 0 | 0 | 0 | 0 | |
15 | 0 | 0 | 0.295 | 0 | 0 | 0 | 0 | 0 | |
20 | 0 | 0 | 0.156 | 0 | 0 | 0 | 0 | 0 | |
25 | 0 | 0 | 0.126 | 0 | 0 | 0 | 0 | 0 | |
30 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
… | … | … | … | … | … | … | … | … | |
100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Wang
Zhang
Table 3 . Frequency of foreign gene flow from insect-resistance transgenic rice HUAHUI-1 to conventional rice varieties (Zhang
Variety | Frequency of gene flow (%) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
0 m | 1 m | 2 m | 3 m | 4 m | 5 m | 6 m | 7 m | 8 m | 9 m | 10 m | ||
Hexi 22-2 | 1 | 1.02 | 0.51 | 0.51 | 0.61 | 0 | 0.52 | 0 | 0 | 0 | 0 | 0 |
2 | 0.51 | 0.5 | 0 | 0 | 0.56 | 0 | 0 | 0 | 0 | 0 | 0 | |
3 | 1.5 | 1 | 1 | 0.6 | 0.51 | 0 | 0 | 0 | 0 | 0 | 0 | |
4 | 0 | 0.51 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Mean | 0.76 | 0.63 | 0.38 | 0.3 | 0.27 | 0.13 | 0 | 0 | 0 | 0 | 0 | |
Tianxiang | 1 | 1.5 | 0.52 | 0.51 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
2 | 0.5 | 1.09 | 0.5 | 0.6 | 0.51 | 0 | 0 | 0 | 0 | 0 | 0 | |
3 | 1 | 0.54 | 0 | 0.63 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
4 | 0.5 | 0.51 | 1 | 0 | 0.51 | 0.51 | 0 | 0 | 0 | 0 | 0 | |
Mean | 0.88 | 0.66 | 0.5 | 0.31 | 0.26 | 0.13 | 0 | 0 | 0 | 0 | 0 | |
Minghui 63 | 1 | 0.5 | 1 | 0.52 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
2 | 1 | 0.51 | 0.53 | 1 | 0.51 | 0.52 | 0 | 0 | 0 | 0 | 0 | |
3 | 1 | 0.51 | 1.02 | 0.52 | 0 | 0 | 0.5 | 0 | 0 | 0 | 0 | |
4 | 1 | 0.5 | 0 | 0 | 0.51 | 0 | 0 | 0 | 0 | 0 | 0 | |
Mean | 0.88 | 0.63 | 0.52 | 0.38 | 0.26 | 0.13 | 0.13 | 0 | 0 | 0 | 0 | |
P1157 | 1 | 1 | 0.59 | 0.58 | 0.5 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
2 | 0.53 | 0 | 0.52 | 0.51 | 0.52 | 0 | 0 | 0 | 0 | 0 | 0 | |
3 | 1.02 | 1.14 | 0 | 0.5 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
4 | 0.5 | 0.6 | 0.57 | 0 | 0.51 | 0.52 | 0 | 0 | 0 | 0 | 0 | |
Mean | 0.76 | 0.58 | 0.42 | 0.38 | 0.26 | 0.13 | 0 | 0 | 0 | 0 | 0 | |
Chunjiang 063 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Mean | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
P13381 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Mean | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
When pollen-mediated foreign genes escape from genetically modified rice to non-transgenic rice, the purity of non-transgenic rice varieties will decrease. Under natural conditions of field production, exogenous genes can be transferred from GM rice to non-GM rice at a high frequency. This will reduce the seed purity of non-GM rice varieties and also make non-GM rice into GM rice, thus affecting the production layout of rice varieties in certain areas. Therefore, it is very important to study pollen transmission rates between different rice varieties, especially between GM and non-GM rice varieties. At the same time, the research can ensure the seed purity of each rice variety, thereby improving the efficiency and quality of industrialized production. Rong
(HY1-: 20,942 strains, HY2-: 23,851 strains, and MSR-: 25,263 strains) for hygromycin resistance screening were obtained. Their statistical results for the identification of hygromycin resistant seedlings showed that the average gene drift frequency of the same combination of GM hybrid rice “Youkefeng 6” and non-GM hybrid rice “Youming 86” was 0.629-0.832%. The gene flow frequency of the same combination of hybrid rice “Liangyouke 6” to hybrid rice “Liangyou 2186” was 0.474-0.792%. The genetic drift rate from the GM restorer line “Feng 6” to the parent “Ming Shun 86” was 0.275-0.362%. Specific PCR amplification results of randomly selected 10% hygromycin-resistant rice seedlings revealed corresponding specific bands of Bt, CpTI, and hpt genes in all samples. In addition, by confirming that resistant seedlings of non-GM rice varieties obtained through hygromycin resistance gene screening were hybrids produced by gene drift, the reliability of hygromycin identification gene drift was verified. The frequency of gene drift fluctuated between different species and different experimental locations. However, the frequency of gene transfer from the three Bt/CpTI GM rice plants to the adjacent non-GM parental control was relatively low, with an average value of less than 0.9%. In addition, the frequency of gene drift between hybrid rice varieties was slightly higher than that of conventional rice varieties.
At the same time, Huang
(Table 4). Research results of Jiang
Table 4 . The frequency of foreign gene flow from insect-resistance transgenic rice HUAHUI-1 to conventional rice varieties (Zhang
Distance | Frequency of gene flow (Mean ± SD) (%) | |||||
---|---|---|---|---|---|---|
CHUNJIANG063 | HEXI22-2 | TIANXIANG | MINGHUI63 | P1157 | P13381 | |
0 | 0 | 0.750 ± 0.289 | 0.875 ± 0.479 | 0.833 ± 0.373 | 0.750 ± 0.250 | 0 |
1 | 0 | 0.625 ± 0.250 | 0.667 ± 0.373 | 0.625 ± 0.025 | 0.583 ± 0.344 | 0 |
2 | 0 | 0.375 ± 0.250 | 0.500 ± 0.289 | 0.583 ± 0.186 | 0.417 ± 0.344 | 0 |
3 | 0 | 0.333 ± 0.373 | 0.350 ± 0.289 | 0.333 ± 0.289 | 0.375 ± 0.250 | 0 |
4 | 0 | 0.250 ± 0.289 | 0.250 ± 0.289 | 0.250 ± 0.289 | 0.250 ± 0.289 | 0 |
5 | 0 | 0.125 ± 0.250 | 0.125 ± 0.250 | 0.125 ± 0.250 | 0.125 ± 0.250 | 0 |
6 | 0 | 0 | 0 | 0.125 ± 0.250 | 0 | 0 |
7 | 0 | 0 | 0 | 0 | 0 | 0 |
8 | 0 | 0 | 0 | 0 | 0 | 0 |
9 | 0 | 0 | 0 | 0 | 0 | 0 |
10 | 0 | 0 | 0 | 0 | 0 | 0 |
Based on the above research results of genetic drift rate of GM rice and non-GM rice varieties, Cui
Table 5 . Gene flow frequency from transgenic rice Ⅱyou 86B to weedy rice (Cui
Weedy rice | Plant method | Germination | Seed amount | Thousand grain weight (g) | Total number of resistant plants | Frequency of gene flow (%) |
---|---|---|---|---|---|---|
TAIZHOU | Transplant | 95.5 | 18675 | 22.1 | 550 | 0.136 |
ZHAOQING | Direct seeding | 86.75 | 16963 | 17.3 | 730 | 0.018 |
Therefore, while foreign resistance genes in GM rice varieties can successfully migrate to their associated wild relatives through their own pollen mobility, they pose a threat to the surrounding agricultural production and the safety of the ecological environment at the same time. The degree of damage to the surrounding environment and crops based on pollen mobility mainly depends on whether the genetically modified crops can be initially hybridized with their wild relatives. It also depends on whether the adaptability of the hybrid has decreased or not. Adaptability is the ability of an individual to survive and reproduce under certain environmental conditions. It determines whether the hybrid offspring can survive normally in nature and form an independent population. Changes in adaptability are related to parental genotypes, resistance genes, environmental conditions, and their mutual effects. Therefore, the hazard assessment of pollen drift of GM rice to surrounding crops and the environment cannot be judged by simply confirming whether it has hybrid compatibility with the GM rice. At the same time, it is necessary to study whether the varieties that have been polluted by GM rice pollen have the corresponding adaptability and stability in order to objectively evaluate and judge their hazards (Cui
The development of genetically modified biotechnology and the commercial application of genetically modified crops have played a huge role in advancing agricultural production and ensuring food security. Today, the commercial cultivation of genetically modified crops has been 25 years. GM crops have been planted in 29 countries around the world, and 42 countries or regions that do not plant GM crops import GM crops for food, feed, and related processing raw materials. This is fully demonstrating the strong vitality of genetically modified biotechnology and its contribution to global agricultural production. Moreover, the second generation of genetically modified products will include many quality traits that can benefit consumers, such as healthy edible oil, high-quality rice, etc., which will enrich the functionality of genetically modified products. However, just like the advent and application of any new technology, while genetically modified biotechnology and its products bring huge economic and social benefits, they might also have some potential risks that require serious scientific research and evaluation. On the other hand, it would be irresponsible to completely deny or even abandon this technology and its products on grounds of unproven and possible risks. We should adopt a scientific, cautious, and serious attitude in the face of environmental biosafety issues that might be brought about by the commercial application of genetically modified rice. We should actively evaluate its risks, take effective countermeasures to possible harms, try to avoid and reduce possible risks, and maximize benefits of commercial application of genetically modified rice. Compared with the traditional rice planting method that uses large amounts of chemical pesticides to control pests, insect-resistant and disease-resistant transgenic rice varieties are much less harmful to the environment than ordinary rice varieties. Therefore, the application of biotechnology in farmland production not only can offer high yield, high quality, disease resistance, and stress resistance of crops, but also can solve problems related to ecology and environment in production through scientific design. Scientific risk assessment of genetically modified biotechnology and its products not only can accumulate large amounts of scientific data and knowledge related to environmental biosafety, but also can escort the safe and sustainable use of these products. Although transgenic technology is a key means for humans to solve population and food problems in the future, it is affected by many commercial interests and social value conflicts involved in the commercialization of genetically modified rice. As a result, there are disagreements and unreasonable disputes in many aspects of the commercialization of genetically modified rice, and it has caused strong social problems and contradictions.
The safety of the ecological environment in the cultivation of genetically modified rice is mainly caused by its pollen mobility. Factors that cause the emergence of genetically modified weeds include: 1) the degree of closeness between the genetically modified crop and its related wild species; 2) the chance of hybridization between different crops and wild relatives; and 3) the frequency of the spread of genetically modified plants based on pollen; After clarifying the above-mentioned influencing factors, the following targeted methods can be taken to suppress the spread of transgenes: 1) set a certain separation distance; 2) stagger the flowering period of transgenic rice with the flowering period of the surrounding ordinary rice; 3) plant ordinary rice as a buffer; and 4) choose male sterile varieties to suppress pollen dispersion.
This work was supported by a grant from the Rural Development Administration Agenda Program (Project No. PJ01423504), Rural Development Administration, Republic of Korea.
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