Bt和Bar基因转化对水稻不同组织生态位微生物群落组成及潜在功能影响

Effects of Bt and Bar transformation on microbial community composition and potential functions in different tissues of rice plants

摘要:

【目的】转Bt基因和Bar基因植物的微生态效应是环境安全评价的重要因素，但关于Bt基因和Bar基因转化引起的水稻基因型改变对水稻不同组织生态位微生物群落组成和潜在功能的影响还无系统研究。【方法】以转Bt基因和Bar基因水稻T1C-1及其亲本对照Minghui63为研究对象，基于细菌16S rRNA基因和真菌ITS高通量测序技术，分析抽穗期T1C-1和Minghui63根际土壤微生物以及根、茎、叶内生菌的群落结构和潜在功能。【结果】细菌和真菌群落多样性在水稻不同组织生态位之间发生显著变化，地下部分组织生态位(根际土壤和根系)微生物多样性显著高于地上部分(叶和茎)。T1C-1显著影响叶片内生真菌的香农指数和辛普森指数，而对茎和根的内生菌以及根际土壤微生物多样性无显著影响。叶片内生真菌曲霉菌属(Aspergillus)和篮状菌属(Talaromyces)相对丰度在T1C-1显著增加，推测其参与碳素代谢、能量代谢和转录作用酶合成等过程。T1C-1和Minghui63微生物群落关联网络分析表明，T1C-1的平均聚类系数和平均度显著高于Minghui63，因而T1C-1提高了相关微生物群落网络复杂程度。通过重建未观测状态对群落进行系统发育研究(phylogenetic investigation of communities by reconstruction of unobserved states, PICRUSt2)，对叶片内生真菌功能酶基因进行功能预测，相对于Minghui63，T1C-1显著改变了碳素代谢、脂类代谢和能量代谢等途径。【结论】相较于根际土壤，叶片内生真菌的群落组成和潜在功能对T1C-1更敏感。尽管如此，T1C-1并未导致叶片内生真菌的多样性指数降低。为了更准确地评估转基因植物的微生态效应，我们需要加强对不同组织生态位内生菌多样性的关注。

Abstract:

[Objective] The microecological effects of transgenic plants with Bt and Bar genes are an important aspect of environmental safety assessment. However, few studies concern the impacts of rice genotypic alterations induced by Bt and Bar transformation on the microbial community composition and potential functions in different tissues of rice plants. [Methods] High-throughput sequencing of bacterial 16S rRNA gene and fungal ITS was performed to analyze the microbial community structure and potential functions in the rhizosphere soil, roots, stems, and leaves of Bt and Bar transgenic rice T1C-1 and its parent Minghui63 (control) at the heading stage. [Results] The bacterial and fungal diversity varied among different tissues in rice plants, being significantly higher in the underground niches (rhizosphere soil and roots) than in the aboveground parts (leaves and stems). T1C-1 significantly affected the Shannon index and Simpson index of endophytic fungi in leaves but had no significant effect on the microbial diversity in the stems, roots, or rhizosphere soil. The endophytic fungi Aspergillus and Talaromyces showed increased relative abundance in the leaves of T1C-1, which suggested their involvement in processes such as carbon metabolism, energy metabolism, and transcription. The average clustering coefficient and average degree of the microbial communities in T1C-1 were significantly higher than those in Minghui63, indicating that T1C-1 increased the complexity of the microbial community network. Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt2) was employed to predict the functional enzyme genes of endophytic fungi in the leaves, which showed that T1C-1 significantly altered the pathways such as carbon metabolism, lipid metabolism, and energy metabolism compared with Minghui63. [Conclusion] The community composition and potential functions of endophytic fungi in leaves were more sensitive to T1C-1 than those in the rhizosphere soil, while T1C-1 did not decrease the diversity of endophytic fungi in leaves. More attention should be paid to the diversity changes of endophytic microorganisms in different ecological niches of plant tissues in the evaluation of the microecological effects of transgenic plants.