Transgenic Bt plants decompose less in soil than non-Bt plants
Transgenic Bt plants decompose less in soil than non-Bt plants
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DOI：
10.1016/j.soilbio.2004.11.006
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发表时间：
2005-06-01
影响因子：
9.7
通讯作者：
Stotzky, G
中科院分区：
文献类型：
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作者：
Flores, S;Saxena, D;Stotzky, G
Bt植物是已经被遗传修饰以表达来自细菌苏云金芽孢杆菌（Bt）亚种的杀虫蛋白（例如Cry 1Ab、Cry 1Ac、Cry 3A）的植物，以杀死以玉米、水稻、烟草、油菜和棉花为食的鳞翅目害虫和以马铃薯为食的鞘翅目害虫。这些转Bt基因植物（Bt+）的生物量在土壤中的分解比其近等基因的非Bt植物（Bt-）的生物量少。用0.5、1或2%（wt wt（-1））的Bt玉米植物的磨碎的、干燥的（50 ℃）叶或茎;用0.5%（wt wt（-1））的Bt水稻、烟草、油菜、棉花和马铃薯植物的磨碎的、干燥的生物量;用没有相应cry基因的近等基因植物的生物量;或不进行改良来改良土壤。土壤总代谢活性由CO2释放量决定。与非Bt植物相比，Bt植物生物量对土壤微宇宙中C以CO2形式的释放量显著降低。这种差异发生与茎和叶从两个杂交种的Bt玉米，其中一个有较高的C：N比比其近等基因的非Bt对应物和其他具有基本相同的C：N比，即使当葡萄糖，氮（NH 4 NO3），或葡萄糖加氮与生物质。其他Bt植物（包括其他两种Bt玉米杂交种）及其近等基因非Bt对应物的C：N比也与其相对生物降解无关。Bt玉米的木质素含量显著高于近等基因非Bt玉米。然而，其他Bt植物的木质素含量，这是显着低于Bt和非Bt玉米，一般没有统计学显着差异，虽然10-66%，从他们各自的非Bt近等值线。Bt玉米和非Bt玉米生物量处理土壤中可培养细菌和真菌的数量以及参与植物生物量降解的代表性酶的活性没有显著差异。所有Bt植物的生物量的降解，在土壤中的情况下，但接种微生物悬浮液从相同的土壤也显着低于各自接种的非Bt植物。向土壤悬浮液中添加链霉素、环己酰亚胺或两者并没有改变BT+和BT -生物量的相对降解，这表明土壤微生物群的差异并不是造成BT+和BT-生物量差异分解的原因。用Bt植物的生物质改良的所有土壤样品对于相应的Cry蛋白是免疫阳性的，并且对烟草天蛾（Manduca sexta）的幼虫是有毒的，烟草天蛾在昆虫生物测定中用作代表性的鳞翅目昆虫（没有对来自马铃薯的Cry 3A蛋白进行杀虫测定）。这些发现的生态和环境相关性尚不清楚。(c)2004爱思唯尔有限公司保留所有权利。
Bt plants are plants that have been genetically modified to express the insecticidal proteins (e.g. Cry1Ab, Cry1Ac, Cry3A) from subspecies of the bacterium, Bacillus thuringiensis (Bt), to kill lepidopteran pests that feed on corn, rice, tobacco, canola, and cotton and coleopteran pests that feed on potato. The biomass of these transgenic Bt plants (Bt+) was decomposed less in soil than the biomass of their near-isogenic non-Bt plant counterparts (Bt-). Soil was amended with 0.5, 1, or 2% (wt wt(-1)) ground, dried (50 degrees C) leaves or stems of Bt corn plants; with 0.5% (wt wt(-1)) ground, dried biomass of Bt rice, tobacco, canola, cotton, and potato plants; with biomass of the near-isogenic plants without the respective cry genes; or not amended. The gross metabolic activity of the soil was determined by CO2 evolution. The amounts of C evolved as CO2 were significantly lower from soil microcosms amended with biomass of Bt plants than of non-Bt plants. This difference occurred with stems and leaves from two hybrids of Bt corn, one of which had a higher C:N ratio than its near-isogenic non-Bt counterpart and the other which had essentially the same C:N ratio, even when glucose, nitrogen (NH4NO3), or glucose plus nitrogen were added with the biomass. The C:N ratios of the other Bt plants (including two other hybrids of Bt corn) and their near-isogenic non-Bt counterparts were also not related to their relative biodegradation. Bt corn had a significantly higher lignin content than near-isogenic non-Bt corn. However, the lignin content of the other Bt plants, which was significantly lower than that of both Bt and non-Bt corn, was generally not statistically significantly different, although 10-66% higher, from that of their respective non-Bt near-isolines. The numbers of culturable bacteria and fungi and the activity of representative enzymes involved in the degradation of plant biomass were not significantly different between soil amended with biomass of Bt or non-Bt corn. The degradation of the biomass of all Bt plants in the absence of soil but inoculated with a microbial suspension from the same soil was also significantly less than that of their respective inoculated non-Bt plants. The addition of streptomycin, cycloheximide, or both to the soil suspension did not alter the relative degradation of Bt+ and Bt - biomass, suggesting that differences in the soil microbiota were not responsible for the differential decomposition of Bt+ and Bt- biomass. All samples of soil amended with biomass of Bt plants were immunologically positive for the respective Cry proteins and toxic to the larvae of the tobacco hornworm (Manduca sexta), which was used as a representative lepidopteran in insect bioassays (no insecticidal assay was done for the Cry3A protein from potato). The ecological and environmental relevance of these findings is not clear. (c) 2004 Elsevier Ltd. All rights reserved.