关键词: 转基因小黑杨, 根际, 细菌, 真菌, 群落变异

Abstract:

【Objective】 The composition of bacterial and fungal communities in rhizosphere soil is not only affected by plant species and varying growth periods, but also by the introduction of foreign genes. The contents of betaine or late-embryogenesis-abundant proteins could be increased in transgenic poplar with betA and TaLEA genes, which were obtained by genetic engineering technology. Drought resistance and salt tolerance were also enhanced in these transgenic poplars. PsnWRKY70 is a negative regulator of the salt stress response signal transduction network. Salt tolerance of WRKY70 inhibitory expression line was significantly higher than that of the line wild type (WT). To clarify the drought resistance and salt tolerance of transgenic poplar with betA, TaLEA and WRKY70, the composition of rhizosphere soil bacterial and fungal communities of transgenic poplar was analyzed to provide a reference for its environmental and ecological security evaluation. 【Method】 In this study, rhizosphere soil was collected from a two-year-old poplar with modified TaLEA, betA and WRKY70 genes, and WT plants were used as controls. The 16S rRNA and ITS sequences of microorganisms in the rhizosphere soil were sequenced using the Illumina-MiSeq highthroughput sequencing platform. The population structures and community compositions of the bacteria and fungi in the rhizosphere soil were then determined and analyzed. The purpose of this study was to understand how transgenic poplar influences the composition of soil microbial communities before the subsequent environmental release. 【Result】 For the composition of bacterial communities, Alpha diversity showed that the Simpson index of betA transgenic poplar was significantly lower than that of the WT, the Shannon and Simpson indexes of WRKY70 transgenic poplar were also significantly lower than that of WT. The fungal indices of the transgenic poplars were significantly lower than those of the WT. The Venn diagram, principal component analysis, and cluster heat map showed that there was little difference in the microbial community structure between TaLEA and WT plants. The microbial communities of transgenic betA and WRKY70 poplars were similar. Based on the composition and abundance analysis at the genus level in the rhizosphere soil collected from transgenic poplars, the abundance of beneficial bacteria, such as Rhodanobacter and Gemmatimonas, increased to varying degrees. The abundance of the beneficial mycorrhizal fungi Inocybe in TaLEA and betA plants was significantly higher than that in the other two samples. The abundance of Sphaerosporella, Hebeloma and Laccaria significantly increased only in TaLEA plants. Conversely, the abundance of pathogenic fungi, such as Didymella and Cadophora, decreased by more than 85% compared with the WT. 【Conclusion】 The diversity of rhizosphere microorganisms was influenced by transgenic poplars, which may be beneficial to plant growth and enhance stress resistance. However, more research is needed to prove whether these microorganisms play a vital role.

Key words: transgenic Populus simonii × P. nigra, rhizosphere, bacteria, fungi, community diversity