J Plant Ecol ›› 2021, Vol. 14 ›› Issue (2): 323-336.DOI: 10.1093/jpe/rtaa099

• Research Articles • Previous Articles     Next Articles

Plant diversity promotes soil fungal pathogen richness under fertilization in an alpine meadow

Xiang Liu1, *, Li Zhang2, Mengjiao Huang2 and Shurong Zhou3   

  1. 1 State Key Laboratory of Grassland Agro-Ecosystem, Institute of Innovation Ecology, Lanzhou University, Lanzhou 730000, China, 2 Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Coastal Ecosystems Research Station of the Yangtze River Estuary, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai 200438, China, 3 Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants, Ministry of Education, College of Forestry, Hainan University, Haikou 570228, China

    *Corresponding author. E-mail: lx@lzu.edu.cn
  • Received:2020-07-23 Revised:2020-09-13 Accepted:2020-11-21 Online:2020-12-18 Published:2021-03-01

Abstract:

Aims

The effects of fertilization on fungal plant pathogens in agricultural soils have been studied extensively. However, we know little about how fertilization affects the relative abundance and richness of soil fungal plant pathogens in natural ecosystems, either through altering the soil properties or plant community composition.

Methods

Here, we used data from a 7-year nitrogen (N) addition experiment in an alpine meadow on the Qinghai-Tibetan Plateau to test how N addition affects the relative abundance and richness of soil fungal plant pathogens, as determined using Miseq sequencing of ITS1 gene biomarkers. We also evaluated the relative importance of changes in soil properties versus plant species diversity under N addition.

Important Findings

Using general linear model selection and a piecewise structural equation model, we found that N addition increased the relative abundance of soil fungal plant pathogens by significantly altering soil properties. However, higher host plant species richness led to higher soil fungal plant pathogen richness, even after excluding the effects of N addition. We conclude that the relative abundance and richness of soil fungal plant pathogens are regulated by different mechanisms in the alpine meadow. Continuous worldwide N inputs (through both fertilizer use and nitrogen deposition) not only cause species losses via altered plant species interactions, but also produce changes in soil properties that result in more abundant soil fungal plant pathogens. This increase in pathogen relative abundance may seriously threaten ecosystem health, thus interrupting important ecosystem functions and services.

Key words: alpine meadow, dilution effect, host–parasite diversity relationship, nitrogen disease hypothesis, plant–soil feedback

摘要:
高寒草甸植物多样性促进了施肥条件下土壤真菌病原体的丰富度
在农业生态系统中,氮添加对植物病原真菌丰富度和相对多度的影响已被基本阐明,然而在自然生态系统中,氮添加如何影响土壤中的植物病原真菌(通过影响植物群落结构或土壤理化指标)仍知之甚少。本研究以青藏高原东部高寒草甸为研究对象,基于7年的氮添加梯度野外实验,使用Miseq平台,针对土壤真菌的ITS1基因进行测序,以评估氮添加对高寒草甸土壤中的植物病原菌丰富度和相对多度的影响,并阐明氮添加通过不同途径(即植物群落结构和土壤理化指标)影响病原菌的潜在机制。基于模型筛选和结构方程模型等统计方法,本研究发现,氮添加通过改变土壤理化指标影响土壤中的植物病原菌相对多度。但是,在排除掉氮添加对土壤中植物病原菌丰富度的影响后,地上植物物种丰富度与土壤中植物病原菌丰富度仍存在显著的正相关性。因此,我们认为高寒草甸土壤中植物病原菌丰富度和相对多度受到不同的机制调控。世界范围内,自然生态系统中氮素输入量的加剧(包括氮沉降和氮肥施用)所引起的植物物种丧失引起了人类的较大关注。除此之外,氮素输入所引起的植物病原菌丰富度和相对多度的变化也值得我们警醒,因为植物病原菌群落结构的改变可能会对生态系统功能和服务产生重要影响。

关键词: 高寒草甸, 稀释效应, 宿主-寄生物多样性关系, 氮素-病害假说, 植物-土壤反馈