Screening Of Mycorrhizal Fungi Promoting Growth Of Anoectochilus Roxburghi And The Optimization Of The Co-culture Conditions

During the production process of Anoectochilus roxburghi, low transplanting survival rate and low quality are the prominent problems. To select the mycorrhizal fungi which could promote growth and development of Anoectochilus roxburghi, and to optimize the co-culture condition which could be applied into the production, might provide new ways for the resolving of problems above. In this study, we collected the roots of wild A. roburghi from Vietnam, Guangxi and Guangdong province of China. After surface sterilization, isolation and purification, more than90mycorrhizal fungi were obtained.The result shows that, when using0.1%mercuric chloride in4min, effects of the surface sterilization was the best, with more variety, less contamination and better isolation stability. Meanwhile, the best medium for isolation is10%PDA.Using a modified MS mudium, five mycorrhizal fungi were obtained. By using staining and different temperature repeat experiments, one fungus named YN-64was selected, which was safety and could promot growth and development of Anoectochilus roburghi. Sequence analysis showed that ITS of18s rDNA of YN-64shared the90%identity with sequences submitted in the Genbank, and without conidial fructification, which revealed that YN-64might be a new species unreported before.To understand effect of mycorrhizal fungi on A roxburgii at different temprature, at26℃and31℃, YN-64co-cultured with A. roxburgii seedlings in modified MS for a month, seedlings growth and mass of A.roxburgii could significantly increased (P<0.05). I While at26℃, seedlings growth and mass of A. roxburgii could extremely significantly increased (P<0.01). However,when the temprature reached at37℃, A. roxburgii seedlings were all died.To confirm effect of mycorrhizal fungi on different kinds in different circumstance, YN-64co-cultured with A. formosanus seedlings on modified MS for3months or1month followed with2months transplanted to outside, growth and mass of A. Formosanus could significantly increased (P<0.05). However, A. roxburgii only promote growth significantly (P<0.05) co-cultured on modified MS for3month, Althought A. roxburgii co-cultured with YN-64in greenhouse outside recovered by cellophane for3month that survival rate lower50%and in greenhouse is87.5%, which height and mass is not significantly.Analysis of the soluble sugar showed that the content of the soluble sugar of the transplanted A. roxburgii is higher than that of non-planted, and that of A. formosanus and A. roxburgii that co-cultured in modified MS for1month followed with transplanted to outside for2months is significantly higher (P<0.05) than others. Under the same circumstance, the content of the soluble sugar of A. roxburgi is significantly higher than that of A. formosanus.