Diversity and Antifungal Activity of Endophytic Fungi Associated with Camellia oleifera

Endophytic fungi strains (n = 81) were isolated from the leaves, barks, and fruits of Camellia oleifera from Hunan province (China) to delineate their species composition and potential as biological control agents of C. oleifera anthracnose. The fungi were identified by morphological and phylogenetic analyses. Fungal colonization rates of the leaves, barks, and fruits were 58.02, 27.16, and 14.81%, respectively. The isolates were identified as 14 genera, belonging to two subdivisions, Deuteromycotina and Ascomycotina; 87.65% of all isolates belonged to Deuteromycotina. The dominant species, occurring with a high relative frequency, were Pestalotiopsis sp. (14.81%), Penicillium sp. (14.81%), and Fusarium sp. (12.35%). The Simpson’s and Shannon’s diversity indices revealed the highest species diversity in the leaves, followed by the barks and fruits. The similarity index for the leaves versus barks comparison was the highest, indicating that the number of endophytic fungal species shared by the leaves and barks was higher than barks and fruits or leaves and fruits. Based on the results of dual culture experiments, only five strains exhibited antifungal activity against C. oleifera anthracnose pathogen, with isolate ty-64 (Oidium sp.) generating the broadest inhibition zones. Our results indicate that the endophytes associated with C. oleifera could be employed as natural agents controlling C. oleifera anthracnose.

Molecular cloning and characterization of an acetylcholinesterase gene Dd-ace-2 from sweet potato stem nematode Ditylenchus destructor / 生物工程学报

A cDNA, named Dd-ace-2, encoding an acetylcholinesterase (AChE, EC3.1.1.7), was isolated from sweet-potato-stem nematode, Ditylenchus destructor. The nucleotide and amino acid sequences among different nematode species were compared and analyzed with DNAMAN5.0, MEGA3.0 softwares. The results showed that the complete nucleotide sequence of Dd-ace-2 gene of Ditylenchus destructor contains 2425 base pairs from which deduced 734 amino acids (GenBank accession No. EF583058). The homology rates of amino acid sequences of Dd-ace-2 gene between Ditylenchus destructor and Meloidogyne incognita, Caenorhabditis elegans, Dictyocaulus viviparous were 48.0%, 42.7%, 42.1% respectively. The mature acetylcholinesterase sequences of Ditylenchus destructor may encode by the first 701 residues of deduced 734 amino acids.The conserved motifs involved in the catalytic triad, the choline binding site and 10 aromatic residues lining the catalytic gorge were present in the Dd-ace-2 deduced protein. Phylogenetic analysis based on AChEs of other nematodes and species showed that the deduced AChE formed the same cluster with ACE-2s.