Morphological and phylogenetic properties of an endophyte from Poa angustifolia grown in Dalian, Liaoning

Abstract:

[Objective] Ten endophytic strains obtained from Poa angustifolia grown in mountains of Huangjin and Baiyu in Liaoning Province were identified. [Methods] Asymptomatic P. angustifolia samples were collected. Plant culms from each sample were stained by Rose Bengal (1%) for 5 minutes. Hyphae were detected under microscope and the infection level was calculated. The fungal strains were isolated, purified and incubated to observe the morphological properties. Fungal genomic DNA samples were extracted by IQS DNA extraction method. Fragments of β-tubulin (tubB) and translation elongation factor 1-α (tefA) genes were amplified by specific PCR primers for isolated strains. Sequences of tubB and tefA were aligned and analyzed by DNAssist 2.2 and ClustalX 1.81, the model was selected by PAUP 4 beta 10 and MrModeltest 2.3. The phylogenetic characteristic of these strains were analyzed through the maximum likelihood tree performed by MrBayes 3.1.2. [Results] Total of 262 Poa angustifolia samples were collected, 57.3% of the plants were infected while no stroma was discovered on the culms. Ten endophytic strains were isolated and purified from these plants samples. Six strains were used to observe the morphological properties. Each of them was identical with those of epichloid endophytes. Comparing with other endophytes from Poa spp. plants, morphological characteristics of the strain were similar to E. liyangensis except smaller conidia and slower growth rate. Five strains were confirmed to possess single alleles of tubB and tefA. Phylogenetic trees based on tubB and tefA fragments respectively revealed that these 5 strains clustered with the second alleles of E. liyangensis. [Conclusion] These results indicated significant differences between these strains and E. liyangensis. Based on the host species and geographic distribution of other endophytes from Poa spp. plants, they might be a new taxonomic group of epichloid endophyte.