滨海湿地植物芦苇可培养内生真菌的多样性

Diversity of culturable endophytic fungi of common reed( Phragmites australis) in coastal wetland

内生真菌在植物生长以及抵御环境胁迫过程中起着非常重要的生态作用.本研究从黄河三角洲滨海湿地1350个芦苇组织切片中分离得到318株内生真菌,通过对rDNA ITS的分型、测序及系统进化分析,研究了该地区芦苇植株根、茎、叶中可培养内生真菌的种类组成及在不同盐度、不同组织中的分布情况.根据序列相似性(以98%为阈值),共获得12个真菌分类操作单元(OTUs).在门级分类水平上,子囊菌门为绝对优势菌群,在各组织和站位中均有分布.芦苇根组织中分离得到的内生真菌OTU数相对较多,叶组织和茎组织中分离到的OTU数相同,且叶中的OTU在根中均存在.潮上区(低盐区)内生真菌OTU数最多,高潮区次之.根中可培养内生真菌的丰富度和多样性指数最高,叶中多样性最低;潮上区丰富度最高,中潮区多样性最高.尽管不同盐度梯度及不同芦苇组织中都有其特异的菌株,但总体看,土壤盐度及不同组织对可培养内生真菌的种类组成的影响并不显著(ANOSIM,P>0.05).链格孢属是所有样品共有的优势菌.

Endophytic fungi play an important ecological role in promoting growth and alleviating environmental stress of host plants. In this study, we investigated the diversity and community com- position of endophytie fungi isolated from the common reed in wetlands of the Yellow River Delta. A total of 318 endophytie fungal isolates were obtained from 1350 tissue （leaf, stem, and root） frag- ments and from three tidal zones with different soil salinity levels, rDNA ITS regions of these isolates were PCR amplified, sequenced, and phylogenetically analyzed. All the sequences were divided in- to 12 operational taxonomic units （OTUs） at the 98% similarity threshold. Aseomyeota was found to be the most abundant flora at the level of the phylum and distributed in all tissues and sites. There were generally richer OTUs in roots than in leaves and stems, and leaves and stems shared the same OTU numbers. All the OTUs retrieved from leaves appeared in roots. The supra tide （low salinity zone） had the most OTUs among the three sampling sites, followed by high tide. Furthermore, the roots had the highest richness and diversity, whereas the leaves had the lowest; supra tide held the highest richness, and the middle tide had the highest diversity. Although unique OTUs could be found in different tissues and tidal zones of different salinity, the communities of culturable endo- phytie fungi were not substantially different among tissues or tidal zones （ANOSIM, P〉 0.05 ）. Alternaria sp. was the shared dominant taxa among all samples.