转Bt水稻土壤跳虫群落组成及其数量变化

Community structure and abundance dynamics of soil collembolans in transgenic Bt rice paddyfields

以转Bt水稻恢复系"克螟稻"(Cry1Ab纯合基因型)和"华恢1号"(Cry1Ab+Cry1Ac融合基因型)以及融合基因型转Bt水稻杂交系"Bt汕忧63",及其对照亲本水稻"秀水11"、"明恢63"和"汕优63"稻田土壤跳虫类群为对象,系统研究转Bt水稻种植下土壤跳虫群落组成及其数量动态变化,以评价不同基因型和不同育种品系转Bt水稻种植下稻田土壤生态安全性。结果表明,转Bt水稻种植导致土壤跳虫个别稀有类群的消失,并显著影响半土生和真土生类群以及土壤跳虫总量,但对群落多样性、均匀度和种类丰富度等影响不显著。与对照亲本相比,Cry1Ab转Bt稻田半土生类群和土壤跳虫总量及其种类丰富度指标显著增加了54.7%、44.4%和26.7%;Cry1Ab+Cry1Ac转Bt杂交稻田球角跳属百分比和真土生跳虫数量显著增加了212.3%和180.4%。就恢复系处理而言,与Cry1Ab转Bt水稻相比,Cry1Ab+Cry1Ac转Bt水稻种植导致棘跳属、球角跳属和原等跳属百分比以及半土生跳虫数量分别显著降低了62.1%、56.7%、61.8%和43.4%,同时,显著提高了裔符跳属百分比达88.2%。就Cry1Ab+Cry1Ac融合基因型转Bt水稻而言,与恢复系相比,转Bt杂交稻种植导致球角跳属和原等跳属百分比,半土生类群和土壤跳虫总量及其种类丰富度和群落多样性显著增加了312.9%和171.6%,302.4%和233.2%,以及54.0%和26.7%,同时,显著降低了裔符跳属百分比达65.5%。

Rice is the most important food crop in the world, which feeds half of the world＇s human population.However the potentially ecological risk of transgenic Bt crops has been being one of the most important issues since the first biotech Bt crop was developed in 1986. Collembolan, one of the key functional groups of soil animals, has been widely used as bioindicator to monitoring soil environmental quality and ecological safety, owing to its large quantity of species and abundances, and the sensitive response to environmental disturbance. The effects of transgenic Bt rice on the community composition and abundance dynamics of soil collembolans were investigated by using the restorer lines, Kemingdao with Cry1Ab and Huahui-1 with Cry1Ab＋Cry1Ac, and the hybrid Bt-SY63 with Cry1Ab＋Cry1Ac in Shandong, China in 2010. Their respective nontransgenic parent control lines, Xiushuidao, Minghui-63 and Shanyou-63, were used as control. Some specifically rare groups of soil collembolan （e.g., Arrhopalites, Cribrochiurus and Isotoma for the pure-transgene restorer, Arrhopalites for the dual-transgene restorer, and Isotoma for the dual-transgene hybrid） were disappeared due to the planting of Bt rice. There were significant effects of Bt rice on the abundances dynamics of the hemiedaphic and euedaphic groups and total soil collembolans. However there was no significant effect on the genus richness and community diversity and evenness. Compared with nontransgenic control rice, the Cry1Ab Bt rice significantly increased the abundances of hemiedaphic group and total soil collembolans, and genus richness by 54.7%, 44.4%, 26.7%, respectively. The proportion of Hypogastrura and the abundance of Euedaphic group in the paddyfields of hybrid of Cry1Ab＋Cry1Ac Bt rice increased by 212.3% and 180.4, compared with its nontransgenic parent control line. Comparison between the two restorer lines with Cry1Ab or Cry1Ab＋Cry1Ac showed that the proportion of Onychiurus,, Hypogastrura Proisotoma, and the abundance of hemiedaphic group decreased by 62.1%, 56.7%, 61.8% and 43.4% respectively, and Folsomides increased by 88.2% in the paddyfields of Cry1Ab＋Cry1Ac Bt rice. Comparison between the restorer line and hybrid with Cry1Ab＋Cry1Ac, Cry1Ab＋Cry1Ac rice increased the proportion of Hypogastrura and Proisotoma,by 312.9%, and 171.6%, the abundances of Hemiedaphic groups by 302.4%, the total soil collembolans 233.2%, as well as genus richness 54.0% and community diversity 26.7%, respectively. However it significantly decreased proportion of Folsomides by 65.5%. The results indicated that the adoption of transgenic Bt rice hybrid can improve the community stability and individual abundances of soil collembolan flora in paddyfield.