Induction Of Traps And Analysis Of Serine Protease Gene Sequence Of Arthrobotrys Oligospora

It is well known that nematode-trapping fungi mainly prey nematodes by special structure—trapping organs. It is very improtant to research the difference between the containing of amino acids between the hyphae with trapping organs and the common vegetative hyphae, to induce traps in laboratory and to analysis the serine protease gene of Arthrobotrys oligospora for understanding the construction of the trapping organs and mechanism of trapping and killing nematodes. So the study was carried out. The results were as follows:Different amino acids had different effects on the growth rate of Arthrobotrys oligospora. Among all of them, L-Histidine, DL-Leucine, L-Leucine and L-Isoleucine could promote the growth significantly; DL-Phenylalanine, L-Phenylalanine, DL-Valine, L-Valine, L-Tryptophan, L-Methionine, L-lysine and L-Glutaric had a little promoting effects, but L-threonine and L-glutaric acid(0.5g/L) had obvious inhibiting effects.The effects of amino acids on traps forming was tested on the CMA. They showed that amino acids not only could induce the traps formation, but also these traps could kill larvae of nematodes effectively. Among all of the amino acids tested, L-Phenylalanine, L-Methionine and DL-valine of 0.05g/L solutions had the best effects to induce traps, and L-Threonine, L-Isoleucine, L-Tryptophan, L-Leucine and L-valine had better effects than the others. Besides, amino acids mainly induced young hyhape of A.oligospora to form trapping organs.The amino acids composition of A. oligospora were measured, the results indicated that the contents of amino acids in the hyphae with traps were much higher than in vegetative hyphae, and they were 31.86mg and 20.58mg in 100mg dry hyphae respectively. All these told us that biochemistry composition changed when the vegetative hyphae transformed into the trapping organs, and the containing of Phenylalanine, Valine and Leucine were much higher than the others in the samples tested.The partial serine proteinase gene of the Arthrobotrys oligospora was amplified with specific primers and compared with the gene sequences from Genbank. The results showed that the whole lenghth of the amplified sequence was 1108bp, The homology in serine protease genes from A.oligospora of Inner Mongolia compared with the strains from Sweden(AY444597) or from Yunnan(AF516146) were 80.3% and 84.1% respectively. Seen from phylogenetic tree, the three strains were consanguinity. All the results showed again that the nematode-trapping fungus—A.oligospora were different in strains from different nations and regions.