不同虫压下转Bt基因水稻与非转基因水稻生态适合度差异

为了解转基因水稻的基因扩散效率和潜在生态风险,以转Bt抗虫水稻Bt63、R1、R2和非转基因常规水稻Ⅱ优838为试材,采用高、低两个不同虫害胁迫水平和转基因与非转基因水稻相间种植方式,通过观察水稻植株营养生长、结实以及对螟虫危害的抗性表现等差异,研究比较了Bt外源基因插入后对水稻植株适合度的影响.结果表明:在低虫害胁迫条件下,转Bt基因水稻在植株分蘖数、生物量鲜重等营养生长指标方面与非转基因对照品系间无明显差异,但株高、穗长、穗重等指标不及对照,且R2和Bt63与对照间差异显著;在高虫害胁迫条件下,3个转Bt基因水稻品系的分蘖数、穗长、穗重等指标明显高于对照.而不同转基因品系株高适合度效应不同,这可能与受体本身的特性相关.3种转基因水稻的单株结实粒数、千粒重与对照在两种虫害胁迫条件下均无显著性差异,Bt基因对受体植株的结实影响不明显.在高虫害胁迫条件下,3种转Bt基因水稻的抗虫能力均显著优于非转基因水稻,表明Bt基因对受体植株的抗虫性影响显著.同时,本研究结果还表明转Bt基因水稻的适合度代价较小,预示了抗虫转基因水稻外源Bt基因在一定环境条件下具有逃逸的可能,但这种风险比较小.

Differences in Ecological Fitness Between Bt Transgenic Rice and Regular Rice Under Different Insect-infestation Pressures

For understanding the possibility and efficiency of foreign gene spread in nature and some potential ecological risk of transgenic rice,a experiment was carried out to investigate the effect of foreign Bt gene insertion on the ecological fitness of the transgenic rice plant.Three Bt transgenic rice cultivars,’Bt63’,’R1’ and ’R2’,and a non-transgenic rice ’Ⅱ-838’ were used as materials.The insect-resistant transgenic and the non-transgenic rice plants were inter-cropped pair-wisely.Two levels of rice stem borer-infestation were set up.The vegetative growth,seed-setting and the resistance to rice stem borers were compared between transgenic and non-transgenic lines.The results showed that both number of tillers and fresh weight of the transgenic rice plant were no differences compared with the control under low pest-infestation pressure,but the plant height,spike length and weight were all lower than those of the non-transgenic rice plant,and ’Bt63’ and ’R2’ were significantly different compared with the control.On the contrary,the number of tillers,spike weight and the length of the transgenic rice plant under high pest-infestation level were significantly higher than those of the control.The plant height was different amongst the transgenic lines,which was presumably because of the receptive cultivars’ traits.Both the number of seeds and thousand-grain weight were no differences between the transgenic and non-transgenic rice lines under two different insect-infestation pressures,suggesting that the effect of foreign Bt gene on seed setting was not significant.In contrast to the non-transgenic rice,three Bt transgenic rice lines displayed a higher resistance to rice stem borer.The fitness of the Bt transgenic rice was distinctly higher under high pest-infestation pressure,which indicated that the effect of foreign Bt gene on the insect-resistance of plant recipients was distinct.At the same time,lower fitness cost of Bt transgenic rice in this experiment implied that it was possible that foreign Bt gene would flow away under certain conditions,but this risk was very low.