不同轮作模式下设施土壤丛枝菌根真菌群落结构的季相变化

以番茄-甜瓜、番茄-豆角两种轮作模式为研究对象,采集番茄生长季(休耕期、花期、果期)的土壤样品,利用Illumina MiSeq高通量测序技术分析两种轮作模式下土壤AM真菌群落结构的差异特征,并探讨驱动AM真菌多样性和群落组成差异的关键因子。结果表明: 引入豆科作物的轮作模式显著改变了AM真菌的α多样性,与番茄-甜瓜相比,番茄-豆角土壤中AM真菌Shannon多样性和Pielou均匀度分别显著降低了24.9%和24.0%。AM真菌丰富度、Shannon多样性和系统发育多样性在番茄生育期(花期、果期)相比于休耕期分别显著下降了55.6%～67.5%、49.6%～51.5%及21.4%～23.7%。引入豆科作物的轮作模式在3个时期均提高了球囊霉属的相对丰度,降低了花期和果期类球囊霉属及原囊霉属的相对丰度。近明球囊霉属的相对丰度在休耕期表现为番茄-甜瓜>番茄-豆角,花期则相反。两性囊霉属、多孢囊霉属和盾巨孢囊霉属仅在花期番茄-豆角土壤中存在。置换多元方差分析(PERMANOVA)和非度量多维度分析(NMDS)结果表明,轮作模式和生长季均显著影响AM真菌群落结构,土壤湿度、pH、速效磷等是调控AM真菌群落结构和多样性的主要环境因子。结构方程模型(SEM)结果进一步表明,轮作模式和生长季主要通过影响土壤pH间接驱动AM真菌群落组成及多样性变化。

Seasonal variations of arbuscular mycorrhizal fungal community in greenhouse soil under different rotation systems

Soil samples were collected at the fallow period, flowering stage, and fruiting stage of tomato under tomato-melon (TM) and tomato-bean (TB) systems. Illumina MiSeq high-throughput pyrosequencing was performed to analyze the differences in AM fungal community between the two rotation systems. We further analyzed the key factors driving the changes in AM fungal diversity and community composition. Results showed that rotation with legume significantly altered the α-diversity of AM fungi. Shannon diversity and Pielou evenness of AM fungi under the TB system were 24.9% and 24.0% lower than that under TM system, respectively. Compared to the fallow period, richness, Shannon diversity, and phylogenetic diversity of AM fungi at the tomato flowering and fruiting stages decreased significantly by 55.6%-67.5%, 49.6%-51.5%, and 21.4%-23.7%, respectively. Rotation with legume (the TB system) promoted the relative abundance of Glomus in all the three sampling times, but reduced the relative abundance of Paraglomus and Archaeospora at the flowering and fruiting stages. Claroideoglomus was more abundant in soils under the TM system than that under the TB system at the fallow period, but the pattern was the opposite at the flowering stage. Ambispora, Diversispora, and Scutellospora were detected only in soil under the TB system. Results of permutational multivariate analysis of variance (PERMANOVA) and non-metric multidimensional scaling (NMDS) analysis showed that both rotation system and growing stage significantly affected the structure of AM fungal community. Soil moisture, pH, and Olsen-P were the predominant factors controlling the variations in the diversity and composition of AM fungal community. Results of structural equation modeling (SEM) further indicated that rotation system and growing stage affected the variations in AM fungal diversity and community structure indirectly via changing soil pH.