Coupling of the chemical niche and microbiome in the rhizosphere: implications from watermelon grafting

Abstract

Grafting is commonly used to overcome soil-borne diseases. However, its effects on the rhizodeposits as well as the linkages between the rhizosphere chemical niche and microbiome remained unknown. In this paper, significant negative correlations between the bacterial alpha diversity and both the disease incidence (r = −0.832, P = 0.005) and pathogen population (r = −0.786, P = 0.012) were detected. Moreover, our results showed that the chemical diversity not only predicts bacterial alpha diversity but also can impact on overall microbial community structure (beta diversity) in the rhizosphere. Furthermore, some anti-fungal compounds including heptadecane and hexadecane were identified in the rhizosphere of grafted watermelon. We concluded that grafted watermelon can form a distinct rhizosphere chemical niche and thus recruit microbial communities with high diversity. Furthermore, the diverse bacteria and the antifungal compounds in the rhizosphere can potentially serve as biological and chemical barriers, respectively, to hinder pathogen invasion. These results not only lead us toward broadening the view of disease resistance mechanism of grafting, but also provide clues to control the microbial composition by manipulating the rhizosphere chemical niche.

Keywords

rhizodeposits / rhizosphere microbiome / diversity / MiSeq sequencing / watermelon grafting

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Acknowledgments

This research was supported by the National Basic Research Program of China (2015CB150503),National Natural Science Foundation of China (31301853), and the Fundamental Research Funds for the Central Universities (KYZ201307). We are grateful to the graduate students and staff involved in maintaining the field plots and collecting soil samples.

Supplementary materials

The online version of this article at http://dx.doi.org/10.15302/J-FASE-2016105 contains supplementary materials (Appendix A)

Compliance with ethics guidelines

Yang Song, Chen Zhu, Waseem Raza, Dongsheng Wang, Qiwei Huang, Shiwei Guo, Ning Ling, and Qirong Shen declare that they have no conflict of interest or financial conflicts to disclose.

This article does not contain any studies with human or animal subjects performed by any of the authors.

RIGHTS & PERMISSIONS

The Author(s) 2016. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)