Arshad Muhammad, Naqqash Tahir, Tahir Muhammad, Leveau Johan H, Zaheer Ahmad, Tahira Syeda Anjum, Saeed Nasir Ahmad, Asad Shaheen, Sajid Muhammad
National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad and Pakistan Institute of Engineering and Applied Sciences, Islamabad, Pakistan.
Institute of Molecular Biology and Biotechnology, Bahauddin Zakariya University, Multan, Pakistan.
J Appl Microbiol. 2022 Nov;133(5):3094-3112. doi: 10.1111/jam.15751. Epub 2022 Aug 18.
Soil microbial communities are among the most diverse communities that might be affected due to transgenic crops. Therefore, risk assessment studies on transgenes are essentially required as any adverse effects may depend not only on the specific gene and crop involved but also on soil conditions.
The present study deals with the comparison of bacterial populations, root exudates and activities of soil enzymes in nontransgenic and AVP1-transgenic wheat rhizosphere, overexpressing vacuolar H + pyrophosphatase for salinity and drought stress tolerance. Amounts of organic acids and sugars produced as root exudates and activities of dehydrogenase, phosphatase and protease enzymes in soil solution showed no significant differences in AVP1-transgenic and nontransgenic wheat rhizosphere, except for urease and phenol oxidase activities. The higher copy number of nifH gene showed the abundance of nitrogen-fixing bacteria in the rhizosphere of AVP1-transgenic wheat compared with nontransgenic wheat. nifH gene sequence analysis indicated the common diazotrophic genera Azospirillum, Bradyrhizobium, Rhizobium and Pseudomonas in AVP1-transgenic and nontransgenic wheat except for Zoogloea detected only in nontransgenic wheat. Using 454-pyrosequencing of 16S rRNA gene from soil DNA, a total of 156, 282 sequences of 18 phyla were obtained, which represented bacterial (128,006), Archeal (7928) and unclassified (21,568) sequences. Proteobacteria, Crenarchaeota and Firmicutes were the most abundant phyla in the transgenic and nontransgenic wheat rhizosphere. Further comparison of different taxonomic units at the genus level showed similar distribution in transgenic and nontransgenic wheat rhizospheres.
We conclude that the AVP1 gene in transgenic wheat has no apparent adverse effects on the soil environment and different bacterial communities. However, the bacterial community depends on several other factors, not only genetic composition of the host plants.
The present research supports introduction and cultivation of transgenic plants in agricultural systems without any adverse effects on indigenous bacterial communities and soil ecosystems.
土壤微生物群落是可能受转基因作物影响的最多样化的群落之一。因此，由于任何不利影响可能不仅取决于所涉及的特定基因和作物，还取决于土壤条件，所以对转基因进行风险评估研究至关重要。
本研究比较了非转基因和过表达液泡H⁺焦磷酸酶以耐受盐分和干旱胁迫的AVP1转基因小麦根际的细菌种群、根系分泌物和土壤酶活性。作为根系分泌物产生的有机酸和糖类的量以及土壤溶液中脱氢酶、磷酸酶和蛋白酶的活性，在AVP1转基因和非转基因小麦根际中除脲酶和酚氧化酶活性外无显著差异。与非转基因小麦相比，nifH基因的较高拷贝数表明AVP1转基因小麦根际中固氮细菌的丰度。nifH基因序列分析表明，AVP1转基因和非转基因小麦中存在常见的固氮属，如固氮螺菌属、慢生根瘤菌属、根瘤菌属和假单胞菌属，除了仅在非转基因小麦中检测到的动胶菌属。通过对土壤DNA的16S rRNA基因进行454焦磷酸测序，共获得了18个门的156282条序列，其中包括细菌序列（128006条）、古细菌序列（7928条）和未分类序列（21568条）。变形菌门、泉古菌门和厚壁菌门是转基因和非转基因小麦根际中最丰富的门。在属水平上对不同分类单元的进一步比较表明，转基因和非转基因小麦根际中的分布相似。
我们得出结论，转基因小麦中的AVP1基因对土壤环境和不同细菌群落没有明显的不利影响。然而，细菌群落取决于其他几个因素，而不仅仅是宿主植物的遗传组成。
本研究支持在农业系统中引入和种植转基因植物，而不会对本地细菌群落和土壤生态系统产生任何不利影响。
