镉胁迫对2种油菜土壤真菌群落的影响

effect of cadmium stress on the soil fungal communities of two oilseed rape species

摘要:

[背景] 人类活动引起的农田重金属污染已成为严重的环境问题。镉（Cd）是最具毒性的重金属之一，能对人体和生态系统构成威胁。[目的] 研究不同浓度镉处理对2种油菜（甘蓝型油菜和芥菜型油菜）的土壤（根际和非根际）真菌群落的影响，为镉的生物修复和健康风险评估提供理论基础。[方法] 对2种油菜土壤（根际和非根际）真菌转录间隔区（Internal Transcribed Spacer，ITS）进行高通量测序，分析镉对根际和非根际土壤真菌群落的影响。[结果] 镉胁迫改变了土壤真菌群落的组成和结构，但对2种油菜土壤真菌群落的α多样性几乎无显著影响。土壤镉浓度和生物量与2种油菜根际土壤真菌群落显著相关，芥菜型油菜非根际土壤真菌群落也与镉污染浓度显著相关。土壤真菌分子生态网络也受到镉污染的影响，甘蓝型油菜根际土壤网络稳定性降低，共生关系减少。甘蓝型油菜非根际土壤网络稳定性升高，但共生关系减少。芥菜型油菜的根际和非根际土壤的网络稳定性升高，而且共生关系增多。[结论] 镉污染会影响土壤系统中的本土真菌群落，从而可能进一步改变土壤的生态系统功能。

关键词:镉;油菜;根际;非根际;真菌群落;分子生态网络

Abstract:

[Background] Heavy metal contamination of agricultural soil is an environmental problem as a result of anthropogenic activities. Cadmium (Cd), one of the most toxic heavy metals, poses health risks to both human being and the ecosystem. [Objective] Aiming at laying a theoretical basis for bioremediation and health risk assessment of Cd, we explored the effect of different levels of Cd on soil (rhizosphere and bulk soil) fungal communities of two oilseed rape species (Brassica napus and B. juncea). [Methods] Through high-throughput sequencing of fungal ribosomal internal transcribed spacer (ITS), the impact of Cd on soil fungal communities of the two species was evaluated. [Results] Cd stress changed the composition and structure of soil fungal communities, but had no significant influence on the alpha diversity of them. Soil Cd concentration and biomass were in significant correlation with the rhizosphere soil fungal communities of the two species and the fungal community of B. juncea bulk soil was significantly correlated with Cd concentration. The molecular ecological networks of soil fungal communities were also affected by Cd pollution, as manifested by the reduced stability and symbiosis of the networks for the fungal communities of B. napus rhizosphere soil, improved stability and attenuated symbiosis of the networks for the fungal communities of B. napus bulk soil, and increased stability and symbiosis of the networks for fungal communities of B. juncea rhizosphere and bulk soil. [Conclusion] Cd pollution influences the indigenous fungal community in soil, which might further change soil ecosystem functions.

Key words:cadmium;oilseed rape;rhizosphere;bulk;fungal community;molecular ecological network