黑胫病感染对烟草茎秆及根际土壤真菌群落结构的影响

烟草黑胫病是由寄生疫霉烟草变种引起的一种对烟草生产造成巨大经济损失的土传病害。本文以健康烟株与感染黑胫病烟株茎秆和根际土壤为研究对象,通过PCR技术扩增样本中真菌转录间隔区的ITS1区域,采用Illumina Miseq高通量测序技术对扩增片段进行测序,旨在了解黑胫病感染对于烟草茎秆和根际土壤真菌群落结构与多样性的影响。本研究20个测序样品,共获得755 599条高质量序列片段,最短序列为200bp,最长序列为356bp,平均序列长度248bp。结果表明,健康烟株和发病烟株根际土壤的优势真菌为子囊菌门Ascomycota、接合菌门Zygomycota和担子菌门Basidiomycota,所有茎秆样品的优势真菌为子囊菌门、担子菌门。健康烟株与感染黑胫病烟株根际土壤样品相对丰度大于1%的属有镰刀菌属Fusarium、被孢霉属Mortierella、隐球菌属Cryptococcus、链格孢属Alternaria和赤霉菌属Gibberella等,其中,健康烟株根际土壤优势属为镰刀菌属（39.35%）和被孢霉属（14.19%）,发病烟株根际土壤镰刀菌属和被孢霉属相对丰度分别为40.26%和20.77%;健康茎秆样品优势属为隐球菌属（31.12%）、链格孢属（18.28%）、镰刀菌属（15.67%）和红酵母属Rhodotorula（13.34%）;病健交界茎秆样品优势属为镰刀菌属（41.36%）、隐球菌属（28.15%）和链格孢属（22.32%）;发病茎秆优势属为隐球菌属（62.14%）和链格孢属（27.75%）。烟株感染黑胫病后,其根际土壤与茎秆样品真菌优势属种类与健康烟株无明显变化,但属水平的相对丰度变化显著。发病烟株茎秆与根际土壤样品真菌群落Sobs、Chao1、Shannon指数较健康烟株降低,Simpson指数上升,表明烟株发病后根际土壤真菌与茎秆内生真菌群落丰富度与多样性降低。该结果对于研究烟草黑胫病发生的微生态机制及其生物防治具有一定的理论指导意义。

The influence of black shank disease infection on fungal community structure of rhizosphere soil and stem of tobacco plants

Black shank disease of tobacco is soil-borne and caused by Phytophthora parasitica var. nicotianae, which can cause huge economic losses to tobacco production. The changes of fungal community structure and diversity in rhizosphere soil and stem of tobacco plants infected by black shank disease were investigated by using PCR amplification of the ITS1 region. The amplified fragments were sequenced using Illumina Miseq high-throughput sequencing technique. A total of 755 599 high-quality sequence fragments were obtained from 20 sequencing samples. The shortest sequence is 200bp, and the longest 356bp, and the average sequence length is 248bp. It was showed that the dominant fungi in rhizosphere soil of healthy and diseased tobacco plants were Ascomycota, Zygomycota and Basidiomycota, while those in stem were Ascomycota and Basidiomycota. The fungal genera with relative abundance of more than 1% in rhizosphere soil samples of healthy and diseased plants were Fusarium, Mortierella, Cryptococcus, Alternaria and Gibberella, of which Fusarium (39.35%) and Mortierella (14.19%) were dominant in rhizosphere soil of healthy plants. The relative abundance of Fusarium and Mortierella in rhizosphere soil of diseased plants was 40.26% and 20.77%, respectively. The dominant genera in healthy stem were Cryptococcus (31.12%), Alternaria (18.28%), Fusarium (15.67%) and Rhodotorula (13.34%). Fusarium (41.36%), Cryptococcus (28.15%) and Alternaria (22.32%) were dominant in symptomatic-asymptomatic junction of stem. Cryptococcus (62.14%) and Alternaria (27.75%) were dominant in diseased stem. The dominant genera in rhizosphere soil and stem of infected plants did not change significantly as compared with the healthy plants, but the relative abundance of the genera changed significantly. The Sobs, Chao1 and Shannon indices of the fungal communities in rhizosphere soil and stem of diseased plants were lower than those of healthy plants, while Simpson index was higher, indicating that the richness and diversity of fungal communities in rhizosphere soil and stem tissue decreased in tobacco plants infected with black shank disease.