疏叶骆驼刺与花花柴互作对氮素固定和根际微生物的影响

植物种间的相互关系通过相关微生物直接或间接的影响来实现。豆科与非豆科植物的互作是研究植物种间关系的理想模型，但是对其互作关系中氮素固定和微生态过程尚不明确。以塔南荒漠优势植物疏叶骆驼刺(Alhagi sparsifolia Shap.)（豆科）和花花柴(Karelini acaspia(Pall.) Less)（菊科）为研究对象，研究了在不同生境（自然和小区）下两者互作对氮素固定和根际微生物的影响。结果表明，在自然和小区两种生存环境下疏叶骆驼刺与花花柴都有氮素转移特征，并且这种转移特征在自然生境下更为明显。在自然生境中从疏叶骆驼刺转移到花花柴的氮素占花花柴总氮的50%左右，而在小区生境中只占30%左右。互作改变了花花柴各组织的化学计量比，在互作条件下花花柴叶片氮素含量比重增加。此外，疏叶骆驼刺与花花柴的互作降低了前者的根际细菌群落的Shannon index，并且改变了其根际土壤细菌的基因功能。互作对花花柴根际微生物群落没有显著影响，但在互作条件下疏叶骆驼刺根际土壤细菌中参与氮素转运的相关基因丰度显著高于单独种植，其中对细根根际土壤细菌的多样性及其基因丰度影响最大。且互作降低了疏叶骆驼刺细根的氮含量。因此，疏叶骆驼刺细根可能是疏叶骆驼刺和花花柴互作的关键部位。本研究为荒漠植被保护与恢复提供了科学依据。

Effects of interaction between Alhagi sparsifolia and Karelinia caspia on nitrogen fixation and rhizosphere microorganisms

The interaction between plant species is realized through the direct or indirect influence of related microorganisms. The interaction between leguminosae and non-leguminosae is an ideal model for studying the relationship between plant species, but nitrogen fixation and microecological processes in the interaction between them are not well understood. In this study, the effects of plant interactions on nitrogen fixation and rhizosphere microorganisms in different habitats-field and plot-were studied, taking Alhagi sparsifolia Shap. (Legume) and Karelinia caspia (pall.) Less (Asteraceae) as the research objects. The study shows that those two species have nitrogen transfer characteristics in the field or in the plot, and the nitrogen transfer characteristics are more obvious in the field. In field habitat, the nitrogen transferred from Alhagi sparsifolia to Karelinia caspia accounted for approximate 50% of the total nitrogen in Karelinia caspia, while in the plot experiment it only accounted for approximate 30%. The interaction changes the stoichiometric ratio of different tissues of Karelinia caspia, and the proportion of nitrogen content in leaves increased under the interaction condition. In addition, the interaction between Alhagi sparsifolia and Karelinia caspia decreases Shannon index of rhizosphere bacterial community of Alhagi sparsifolia, and the interaction changes the gene function of the soil bacteria in the rhizosphere of Alhagi sparsifolia. The interaction has no significant effect on rhizosphere microbial community of Karelinia caspia. But gene abundance involved in nitrogen transportation in the rhizosphere is significantly higher than that in the single planting, among which the interaction has the greatest effect on the diversity of bacteria and gene function in the fine root rhizosphere of Alhagi sparsifolia. Moreover, the nitrogen content of fine roots of Alhagi sparsifolia is decreased by the interaction. Therefore, the Alhagi sparsifolia fine root could be the crucial part during the interaction between Alhagi sparsifolia and Karelinia caspia. This study provides a scientific basis for the protection and restoration of desert vegetation.