【摘要】 环境和遗传分化共同影响植物的功能性状,进而能够通过根系分泌物影响根际微生物。本研究利用同质园试验,通过高通量测序技术,基于固氮酶基因nifH的同源性,分析同质园栽培的不同种源小叶锦鸡儿(Caraganamicrophylla)、中间锦鸡儿(C. liouana)和荒漠锦鸡儿(C.roborovskyi)根际土壤固氮菌多样性,并探究其与种源地气候及同质园土壤属性的关系。结果表明, 3种锦鸡儿植物根际土壤固氮菌隶属6门9纲18目21科33属72种,其中变形菌门、疣微菌门和蓝细菌门为优势门,优势属为中慢生根瘤菌属(Mesorhizobium)、固氮氢自养单胞菌属(Azohydromonas)和慢生根瘤菌属(Bradyrhizobium)。3种锦鸡儿根际土壤固氮菌α多样性种间差异不显著,但中间锦鸡儿和荒漠锦鸡儿根际土壤固氮菌的α多样性存在显著的种内差异(P<0.05),小叶锦鸡儿和荒漠锦鸡儿根际土壤固氮菌群落结构存在显著的种内差异(P<0.05)。冗余分析表明同质园土壤p H和种源地年均温分别是影响3种锦鸡儿根际土壤固氮菌多样性和群落结构变化的主要因子,说明3种锦鸡儿属植物根际土壤固氮菌群落多样性受同质园环境与遗传分化的共同调控。本研究结果为锦鸡儿属植物的生态适应机制和引种栽培提供理论依据和数据支持。更多还原

【Abstract】 Aims: Environmental and genetic factors are believed to be the main drivers of variation of plant function traits, which may further influence rhizosphere soil bacteria through root exudates. However, it still remains unclear whether the genetic differentiation would affect the diversity and community structure of nitrogen-fixing bacteria in the rhizosphere soil of plant species.Methods: A common garden experiment was established to examine the diversity and community structure of nitrogen-fixing bacteria in the rhizosphere soil of three Caragana from different provenances by using high-throughput sequencing techniques, which was subsequently correlated with the provenance climates and common garden soil properties to investigate how the environmental factor and genetic differentiation affect the rhizosphere nitrogen-fixing bacterial diversity and community structure. Results: The present results demonstrated that the rhizosphere nitrogen-fixing bacteria of three Caragana species belonged to 6 phyla, 9 classes, 18 orders, 21 families, 33 genera and 72 species. Proteobacteria, Verrucomicrobia and Cyanobacteria were the main dominant phyla of the three Caragana species of nitrogen-fixing bacteria in the rhizosphere soil, and Mesorhizobium, Azohydromonas and Bradyrhizobium were the dominant genera. There were no significant differences in the diversity and community structure of rhizosphere nitrogen-fixing bacteria among the three Caragana species, but significant differences in the α diversity index between provenances were observed in C. liouana and C. roborovskyi(P < 0.05). The community structure between provenances of C. microphylla and C. roborovskyi was also significant(P < 0.05). Furthermore, redundancy analysis showed that soil pH of the common garden and mean annual temperature(MAT) of provenance were the dominant factors respectively affecting the diversity and community of rhizosphere nitrogen-fixing bacteria of the three Caragana species. Conclusion: In summary, our results indicate that the common garden environment and genetic differentiation jointly shape the diversity and community structure of nitrogen-fixing bacteria in the rhizosphere soil of Caragana species. This research can provide important theoretical basis and data support for the ecological adaptation mechanism and introduction and cultivation of Caragana.更多还原