水稻基因飘流的生物学主控因子研究

Along with the rapid development of transgenic rice, the potential risk of environment and food has become one of the major concerns. In accordance with this situation, we have systematically studied the rice gene flow patterns in multiple years since 2002, the researches on the gene flow of transgenic rice to rice varieties, hybrid rice sterile line and the common wild rice had been conducted. Simultaneously, gene flow models in different directions and locations have been established in the southern rice growing area of China. However, there are some basic scientific questions which have not been answered yet. In this application, we will focus on the following 2 points to study：Elucidation of the effect of pollen competitiveness on rice gene flow, both in terms of quantitative and genetic competitiveness, and the correlation analysis of floral characters of common wild rice (Oryza rufipogon Griff.) and its outcrossing rate. The quantitative competitiveness is determined by using a male sterile line as a female parent and two pollen donors having similar genetic background (one is transgenic with bar gene inserted and the other is non-transgenic, wild type). The two donors are planted at different ratios (0:10, 2:8, 4:6, 5:5, 6:4, 8:2, 10:0). While the genetic competitiveness is investigated by using two donors either Indica transgenic with bar gene plus Japonica non-transgenic cultivars or vice versa. The relationship between the floral characters of common wild rice and its outcrossing rate will be analyzed. Finally, the parameterization of major boiological factors controlling rice gene flow can be obtained and the model will be further optimized and practicalized, which can provide a serious of data-set for risk assessment and regulation of rice transgene flow on the scientific basis.

我国转基因水稻研发快速发展，基因飘流可能引起的环境潜在风险受到人们的广泛关注。自2002年起，本课题组在水稻基因飘流规律方面开展工作，研究了转基因水稻向水稻品种、杂交水稻不育系和普通野生稻的基因漂流，建立了转基因在不同方向上的基因飘流模型。在此基础上，本项目拟选择两个国内外水稻基因飘流研究中尚未涉及的科学问题，重点研究水稻花粉竞争力和异交结实特性对基因飘流的影响。采用花粉数量竞争（具有相似遗传背景的籼籼、粳粳之间，其中一个为转基因水稻）、花粉遗传竞争与基因飘流率之间的数值关系（两种供体种植比例0:10, 2:8, 4:6, 5:5, 6:4, 8:2, 10:0），分析花粉数量竞争和遗传竞争、异交结实性在基因漂流中的作用，普通野生稻花器性状与异交结实性的关系。通过基因飘流生物学主控因子的研究，有利于优化水稻基因飘流模型，为转基因水稻环境安全评估与监管提供实验数据和科学依据。

基因飘流是水稻（Oryza sativa L.）转基因安全性研究中的重要内容。在前期转基因水稻向水稻品种、杂交水稻不育系和普通野生稻基因飘流基本规律和模型研究的基础上，选择两个国内外水稻基因飘流研究中尚未涉及的科学问题，重点研究水稻花粉竞争力和异交结实特性对基因飘流的影响，分析基因飘流中的生物学主控因子。分别以籼、粳型转基因水稻和相应类型常规水稻为花粉供体、水稻不育系为花粉受体，研究籼、粳型花粉双供体在基因飘流中的竞争性。籼、粳型花粉供体按照转基因:非转基因的种植行比1:9、2:8、3:7、4:6、5:5、6:4、7:3、8:2、9:1进行配置，分析花粉数量竞争和遗传竞争、异交结实性对基因飘流率的影响及其相互关系。研究结果表明，随着转基因供体花粉量的增加，基因飘流频率增大，水稻基因飘流率与转基因水稻的花粉量比例呈一定的正相关性。不同亚种类型的花粉源配置下的基因飘流率差异较大，同一亚种类型配比，籼（籼/籼）或粳（粳/粳）亚种内花粉供体的基因飘流竞争力基本相同；当两种不同亚种类型花粉源进行配置时，同等行比情况下籼稻花粉的竞争性大于粳稻。由此说明水稻相同亚种的籼-籼与粳-粳双供体组合的基因飘流频率受数量竞争性的影响；而不同亚种双供体的基因飘流频率，受花粉源的数量竞争性和遗传竞争性的共同影响。相同亚种花粉源组合的数量竞争性表现为基因飘流率与转基因花粉供体行比呈S曲线的关系；籼-粳型花粉源组合在数量竞争与遗传竞争共同作用下，籼稻基因飘流率大于粳稻，说明籼稻花粉竞争性强于粳稻。花粉数量竞争性和遗传竞争性共同影响水稻的基因飘流。. 普通野生稻开花特征特性的研究结果表明，普通野生稻的自交结实性与其花器性状之间没有显著相关性；普通野生稻和栽培稻的异交结实率与其花器性状和自交结实率之间也无显著相关关系。此外，花粉隔离试验结果表明，隔离措施下的基因飘流率远低于非隔离措施下的基因飘流频率，但隔离布措施在不同方向上的隔离效果不同。