不同生境黑老虎根际和内生真菌多样性分析

Diversity of rhizosphere and root endophytic fungi in Kadsura coccinea under different habitats

关键词:  黑老虎, ITS, Illumina高通量测序, 真菌群落, 土壤环境因子, 多样性

Key words:  Kadsura coccinea, ITS, Illumina high-throughput sequencing, fungal community, soil environmental factors, diversity

摘要:

为探究不同生长条件下黑老虎根际和根部内生真菌群落组成和多样性及其与土壤环境因子的相关性,该文应用Illumina高通量测序方法对贵州3个不同生境下黑老虎根际和根部内生真菌进行了研究。结果表明:(1)3种生境下,根际土壤真菌OTU数量(3 867)远多于根部内生真菌(801),其中根际土壤真菌共有的OTU为72个,共注释到5个门、49个属,大多为子囊菌门; 属水平上被孢霉属、外瓶柄霉属、 柱孢属占比较高; 根部内生真菌共有的OTU为14个,共注释到2个门、11个属,子囊菌门(13个,占比92.9%)占绝对优势,属水平上被孢霉属、外瓶柄霉属、 柱孢属和丛赤壳属占比最高; 所有样本中,共有的OTU仅为6个,注释到2个门、5个属,子囊菌门(5个,占比83.3%)为优势门; 在属水平上,占比最高的为外瓶柄霉属(2个,33.3%),其余分别为被孢霉属、柱孢属和丛赤壳属 。Alpha多样性分析表明,根际土壤的真菌群落多样性和丰富度均显著高于根部内生真菌,而野生生境的真菌多样性高于栽培生境。(2)在门水平上,3个生境下主要内生真菌类群均为子囊菌门(Ascomycota)和担子菌门(Basidiomycota),占总菌群的88.28%; 在属水平上,不同生境条件下,根际和根部内生真菌群落结构差异明显; 栽培生境下,根部内生真菌菌群具有一定的偏好性,而野生生境下,根部内生真菌菌群均匀度更高; FUNGuild真菌群落功能预测显示,栽培生境下的病理-腐生营养型(pathotroph-saprotroph)在根部内生真菌中占比较高,而野生生境下的腐生营养型(saprotroph)及共生营养型(symbiotroph)占比较高。(3)土壤环境因子对根部内生真菌和根际真菌的影响方式不同,其中土壤总钾(TK)和土壤总磷(TP)与黑老虎根部内生真菌香农指数和辛普森指数显著正相关,而土壤有机质(SOM)、总氮(TN)和速效氮(AN)与黑老虎根际土壤真菌Ace指数和Chao1指数显著正相关。综上表明,土壤有机质、总氮、速效氮是影响黑老虎根际土壤真菌群落的主要土壤环境因子。

Abstract:

Kadsura coccinea is a perennial vine medicinal plant, and its growth, development, and authentic medicinal qualities are affected by growing habitat, rhizosphere soil, and endophytic fungi. In order to explore the composition and diversity of fungal community in K. coccinea under different habitats, as well as their correlation with soil environmental factors, the rhizosphere and root endophytic fungi of K. coccinea from three different habitats in Guizhou were studied based on Illumina high-throughput sequencing method. The results were as follows:(1)Under three habitats, the number of OTU detected in rhizosphere soil(3 867)was much more than that in root endophyte(801). The common OTU of rhizosphere soil was 72, which were annotated to 5 phyla and 49 genera, most of which were ascomycetes. At the genus level, the proportion of Mortierella, Exophiala, and Cylindrocarpon was relatively high. The common OTU of root endophytic fungi was 14, which were annotated to 2 phylums and 11 genera. Ascomycetes(13, accounting for 92.9%)were overwhelmingly dominant. At the genus level, Mortierella, Exophiala, Cylindrocarpon and Nectria were dominant genra. There were only 6 OTU in total, annotated to 2 phylums and 5 genera, and the ascomycetes phylum(5, accounting for 83.3%)were the dominant phylum. At the genus level, Exophiala(2, 33.3%)accounted for the highest proportion, and the rest were Mortierella, Cylindrocarpon and Nectria, respectively. Alpha diversity analysis showed that the diversity and richness of fungal communities in rhizosphere soil were significantly higher than those in root endophytic fungi, while the diversity of fungi under wild habits was higher than that under cultivated habits.(2)At the phylum level, the main endophytic fungal groups under three habitats were Ascomycota and Basidiomycota, accounting for 88.28% of the total flora. At the genus level, the community structures of endophytic fungi in rhizosphere and root were significantly different under different habitats. The endophytic fungi flora in the root had a certain preference under the cultivation habitat, while the evenness was higher under the wild habitat than that under cultivation habitat. The prediction functions of fungal community based on FUNGuild showed that pathotroph-saprotroph type in the root endophytic fungi was relatively high under the cultural habit, while the proportion of saprophytic type and symbiotroph type was relatively high under the wild habit.(3)Soil environmental factors had different effects on root endophytic fungi and rhizosphere fungi in K. coccinea. Total potassium(TK)and total phosphorus(TP)in soil were positively correlated with Shannon index and Simpson index of endophytic fungi in K. coccinea root; whereas, soil organic matter(SOM), total nitrogen(TN)and available nitrogen(AN)were positively correlated with Ace index and Chao1 index of rhizosphere soil fungi. In conclusion, soil organic matter, total nitrogen and available nitrogen are the main soil environmental factors affecting the rhizosphere soil fungal community of the K. coccinea.