Effects of clonal integration on microbial community composition and processes in the rhizosphere of the stoloniferous herb Glechoma longituba (Nakai) Kuprian.

Ningfei Lei,Jinsong Chen,Shijun Ni,Jun Li,Fei-Hai Yu

doi:10.1371/journal.pone.0108259

Ningfei Lei, Jinsong Chen + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0108259

Copy DOI

Abstract

The effects of rhizodeposition on soil C and N availabilities lead to substantial changes of microbial community composition and processes in the rhizosphere of plants. Under heterogeneous light, photosynthates can be translocated or shared between exposed and shaded ramets by clonal integration. Clonal integration may enhance the rhizodeposition of the shaded ramets, which further influences nutrient recycling in their rhizosphere. To test the hypothesis, we conducted a pot experiment by the stoloniferous herb Glechoma longituba subjected to heterogeneous light. Microbial biomass and community composition in the rhizosphere of shaded offspring ramets, assessed by phospholipid fatty acids (PLFAs) analysis, were markedly altered by clonal integration. Clonal integration positively affected C, N availabilities, invertase and urease activities, N mineralization (Nmin) and nitrification rates (Nnitri) in the rhizosphere of shaded offspring ramets. However, an opposite pattern was also observed in phenoloxidase (POXase) and peroxidase (PODase) activities. Our results demonstrated that clonal integration facilitated N assimilation and uptake in the rhizosphere of shaded offspring ramets. The experiment provides insights into the mechanism of nutrient recycling mediated by clonal integration.

Highlights

Rhizosphere, a zone of usually high microbial turnover and activity, has been coined to describe the soil adjacent to and influenced by plant roots [1]
Changes in soil properties Clonal integration significantly increased Total soil organic carbon (TOC), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations in the rhizosphere of shaded offspring ramets as well as C/N, whereas no effects of clonal integration on soil moisture, pH and total nitrogen (TN) were observed in the rhizosphere of shaded offspring ramets (Table 2)
Changes in microbial community composition A principal component analysis (PCA) based on phospholipid fatty acids (PLFAs) biomarkers of different microbial groups revealed that microbial community composition was clearly distinct in the rhizosphere of shaded, connected offspring ramets compared to shaded, severed offspring ramets (Fig. 2)

Summary

Introduction

Rhizosphere, a zone of usually high microbial turnover and activity, has been coined to describe the soil adjacent to and influenced by plant roots [1]. Plant-derived root exudates are primary sources of labile C inputting to soil [2,3]. Especially ectomycorrhizal (ECM) fungi involved in nitrogen turnover (e.g. mineralization and nitrification), prefer the substrates with larger C/N ratios [12]. Microbial processes, such as extracellular enzyme activities [1,13,14], N mineralization and nitrification [15,16], are mediated by specific groups of microorganisms in the rhizosphere. Two experiments to disrupt root exudation into the soil demonstrated that decreased resource availability negatively affected nitrogen mineralization and nitrification in the rhizosphere via rhizodeposition from plant root [1,15]. Microbial processes are highly sensitive to the availabilities of labile C and N in the rhizosphere [5]

Methods

Results

Conclusion