Liu Yongbo, Ge Feng, Liang Yuyong, Wu Gang, Li Junsheng
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
State Key Laboratory of Integrated Management of Pest and Rodents, Institute of Zoology, the Chinese Academy of Sciences, 8 Dayangfang, Beijing, 100101, China.
BMC Biotechnol. 2015 Apr 26;15:27. doi: 10.1186/s12896-015-0141-0.
Transgene flow through pollen and seeds leads to transgenic volunteers and feral populations in the nature, and consumer choice and economic incentives determine whether transgenic crops will be cultivated in the field. Transgenic and non-transgenic plants are likely to coexist in the field and natural habitats, but their competitive interactions are not well understood.
Field experiments were conducted in an agricultural ecosystem with insecticide spraying and a natural ecosystem, using Bt-transgenic rice (Oryza sativa) and its non-transgenic counterpart in pure and mixed stands with a replacement series.
Insect damage and competition significantly decreased plant growth and reproduction under the coexistence of transgenic and conventional rice. Insect-resistant transgenic rice was not competitively superior to its counterpart under different densities in both agricultural and natural ecosystems, irrespective of insect infection. Fitness cost due to Bt-transgene expression occurred only in an agroecosystem, where the population yield decreased with increasing percentage of transgenic rice. The population yield fluctuated in a natural ecosystem, with slight differences among pure and mixed stands under plant competition or insect pressure. The presence of Chilo suppressalis infection increased the number of non-target insects.
Plant growth and reproduction patterns, relative competition ability and population yield indicate that Bt-transgenic and non-transgenic rice can coexist in agroecosystems, whereas in more natural habitats, transgenic rice is likely to outcompete non-transgenic rice.
转基因通过花粉和种子传播会导致自然界中出现转基因自生植物和野生种群，而消费者的选择和经济激励因素决定了转基因作物是否会在田间种植。转基因植物和非转基因植物可能会在田间和自然栖息地中共存，但其竞争相互作用尚未得到充分了解。
在一个进行杀虫剂喷洒的农业生态系统和一个自然生态系统中开展田间试验，使用转Bt基因水稻及其非转基因对照品种，设置纯种植株和混种植株，并采用替代序列设计。
在转基因水稻和常规水稻共存的情况下，虫害和竞争显著降低了植株的生长和繁殖。在农业和自然生态系统中，无论有无虫害，抗虫转基因水稻在不同种植密度下均不具有比其对照品种更强的竞争优势。转Bt基因表达导致的适合度代价仅出现在农业生态系统中，即随着转基因水稻比例的增加，群体产量下降。在自然生态系统中，群体产量有波动，在植株竞争或虫害压力下，纯种植株和混种植株之间差异不大。二化螟感染的存在增加了非靶标昆虫的数量。
植株的生长和繁殖模式、相对竞争能力和群体产量表明，转Bt基因水稻和非转基因水稻能够在农业生态系统中共存，而在更自然的栖息地中，转基因水稻可能会比非转基因水稻更具竞争优势。
