Page 23 - 《广西植物》2020年第5期
P. 23
5 期 徐祥林等: 罗汉果内生真菌多样性研究 6 1 9
Abstract: Involved in the biological co ̄existenceꎬ endophytic fungi can confer adaptative advantages to the plant hostꎬ
such as enhance growthꎬ competitivenessꎬ and induce stress tolerance and the producing of bioactive metabolites of the
host plantꎬ displaying an important role in biocontrol of plant diseases. There are many species of endophytic fungi in
plants. The identification based on amplification and sequencing analysis of ITS geneꎬ combined with traditional morpho ̄
logical identification methodsꎬ could fast and effectively identify endophytic fungi. In this studyꎬ the identification as well
as the diversity of endophytic fungi isolated from Siraitia grosvenorii were studied. The results were as follows: A total of
150 endophytic fungi were obtained by a tissue culture methodꎬ including 96 and 54 fungal isolates respectively isolated
from pistillate plant and staminiferous plant of S. grosvenorii. Among themꎬ 122 isolates were classified into nine genera
based on the morphology identification and sequencing analysis of ITS geneꎬ which belong to phylum Ascomycotaꎬ inclu ̄
ding Dothideomycetes and Sordariomycetes. Dothideomycetes contained three families and three generaꎬ and Sordariomy ̄
cetes contains six families and six genera. The most frequent genera were Colletotrichum and Fusarium. There were differ ̄
ent colonization rates and isolation rates between pistillate plant and staminiferous plant of S. grosvenoriiꎬ i.e.ꎬ in the pis ̄
tillate plantꎬ the root possessed the highest colonization rate and isolation rateꎬ while the leaves possessed the lowest. The
opposite happened in staminiferous plant. Additionallyꎬ distributions of endophytic fungi were different in different
tissues of both pistillate plant and staminiferous plant of S. grosvenorii. Combined with the similarities of community com ̄
position of endophytic fungi in different tissuesꎬ the results indicate that endophytic fungi have the hosts and tissues pref ̄
erences. The diversity indices of endophytic fungi in different tissues ranged from 0.11 to 0.69ꎬ among which the root of
pistillate plant had the highest diversity indices.
Key words: endophytic fungiꎬ colonization rateꎬ isolation rateꎬ relative frequencyꎬ Shannon ̄Weiner(H′)ꎬ similarity
植物内生真菌是指那些在其生活史中的某一 录区包括 5S rDNA、18S rDNA、5.8S rDNA 和 28S
阶段或全部阶段生活在健康植物组织内ꎬ对宿主 rDNAꎬ它们在染色体上头尾相连、串联排列ꎬ相互
植物组织不引起明显病害症状的真菌ꎬ但在植物 之间由间隔区分隔ꎮ 其中ꎬ18S rDNA、5.8S rDNA
中却普遍存在ꎬ且与宿主植物协同进化、互惠共生 和 28S rDNA 基因组成一个转录单元ꎬ三者高度保
(Fe Andres et al.ꎬ 2017ꎻSudha et al.ꎬ 2016ꎻNisa et 守ꎬ可在属、科、目水平上用于不同生物种的比较ꎬ
al.ꎬ 2014ꎻ Zhang et al.ꎬ 2012ꎻ Aly et al.ꎬ 2010)ꎮ 其间的间隔区为内转录间隔区包括 ITS1 和 ITS2
一方面ꎬ内生真菌从宿主中吸取营养供自己生长 两部分ꎬ进化相对迅速而具多态性ꎬ可用于属内或
所需ꎻ另一方面ꎬ其产生的次生代谢产物可促进宿 种内的系统学研究ꎮ rDNA 的 ITS 序列进化速度较
主植物营养吸收、提高植物抗生物逆境和非生物 快且具有一定的保守性ꎬrDNA 序列分析已成为内
逆境的能力、刺激植物产生活性物质等( Zhao et 生真菌鉴定的常用方法(刘春来等ꎬ2007)ꎮ
al.ꎬ 2011)ꎮ 其是植物病虫害生物防治领域的重 罗汉果( Siraitia grosvenorii) 为葫芦科( Cucur ̄
要研究内容之一( 姜道宏ꎬ2015)ꎮ 植物内生真菌 bitaceae)罗汉果属(Siraitia)多年生攀援藤本植物ꎬ
种类繁多ꎬ目前对其鉴定主要是采用形态学结合 主要分布在广西、广东、湖南、江西、贵州等省( 区)
分子生物学的方法ꎮ 该方法克服了传统的仅依赖 的部分地区ꎬ其中以广西桂林的临桂、永福、兴安、
形态、生化等表型特征来进行鉴定而存在的诸如 资源、龙胜、灵川的栽培面积最大ꎬ是我国最大的
人为因素影响大、耗时长等的局限( 任燕ꎬ2018)ꎮ 罗汉果生产基地( 闫海锋等ꎬ2011)ꎮ 罗汉果具有
在分子生物学鉴定方法中ꎬ真菌核糖体中的 DNA 清热润肺、保肝护肝、利咽开音、提高机体免疫功
内转录间隔区( internal transcribed spacerꎬITS) 已 能、减低血糖、抗肿瘤、抗氧化等功效ꎬ国家卫生
广泛用于真菌属种间的系统学研究ꎮ 真核生物基 部、中医药管理局将其列入第一批“ 既是食品又是
因组 中 编 码 rRNA 的 基 因 称 为 rRNA 基 因 或 药品的品种”名单ꎬ目前已广泛用于医药、保健品、
rDNAꎮ rDNA 一般由转录区和非转录区组成ꎮ 转 食品和饮料等领域( 张维等ꎬ2014ꎻ李典鹏和张厚