Isolation And Identification Of Pathogenic Fungi Causing Diseases On Dendrobium Officinale And The Research Of Growth-promoting Effect Of Piriformospora Indica

Dendrobium officinale Kimura et Migo belongs to Orchidaceae Dendrobium Sw. and perennials. Dendrobium officinale often attaches to the trunk or rock. Modern pharmacology and clinical application has proved that Dendrobium officinale has many good effects, such as enhancing immunity, promoting digestion and protecting the liver and gallbladder. It was respected as the first of "Chinese nine immortality " by Taoist medicine. It has a widely of application prospects in the field of edible, medical and health care. However, the growth of wild Dendrobium officinale needs very demanding environments, so wildlife resources is rare. With the increasing market demand for Dendrobium officinale, more and more people choose to cultivate Dendrobium officinale.There are many diseases in the process of Dendrobium officinale planting, and the prevention of Dendrobium officinale is still lack of systematic research up to now. Therefore, this article is mainly carried out in the following two aspects of some preliminary exploration:1. Isolated and identified the pathogens of Dendrobium officinale, and research the biological characteristics of the pathogens and the sensitivity on some fungicides.2.the growth-promoting effect of Piriformospora indica on Dendrobium officinale, and exploring the transformation system of Piriformospora indica preliminarily. The main results are as follows:(1) By collecting samples of Dendrobium officinale diseases, isolating pathogens and identificating them with the measures of morphological and molecular biology. Experimental results show that there are four common disease pathogens of Dendrobium officinale. The pathogen of Dendrobium officinale southern blight is Sclerotium rolfsii. The pathogen of Dendrobium officinale black spot is Alternaria tenuissima. There are two kinds of pathogens causing Dendrobium officinale stem rot:Fusarium incarnatum and Fusarium proliferatum. The pathogen of Dendrobium officinale gray mold is Botrytis cinerea. Then measured the biological characteristics of these pathogens and fungicide sensitivity. The suitable environment for growth of Sr1is pH4-8,25℃-30℃. The suitable environment for growth of At1is pH5-5.7,20℃-30℃. The suitable environment for growth of Fi1and Fp1is pH<7,25℃-30℃. The suitable environment for growth of Bc1is pH<7,20℃-25℃. The optimum growth environment for the pathogens are consistent with the law of diseases. The determination of carbon and nitrogen source show that the impact of different carbon sources on Sr1, Fi1, Fp1and Bc1growth are significant. Sr1prefer mannitol as carbon source for growth, Fi1prefer D-glucose, sucrose and mannitol as carbon source for growth, Fp1prefer mannitol and L-arabinose as carbon source for growth and Be1prefer D-fructose and D-glucose as carbon source for growth. Different nitrogen treatments on the four strains (Sr1, Fi1, Fp1, Bc1) have no significant impact. The strains At1grow well in different carbon and nitrogen treatments, indicating that the strain have a good ability to adapt to growth. Fungicide sensitivity test experiments show that trichodermin, rapamycin, tebuconazole and iprodione can be selected as southern blight fungicides. Prochloraz and iprodione can be selected as black spot fungicides. Prochloraz can be selected as stem rot fungicides. Rapamycin on Dendrobium officinale stem rot also has preventive effects, in addition tebuconazole can be used to control stem rot caused by Fusarium proliferatum. Rapamycin, prochloraz and iprodione can be selected as Dendrobium officinale gray mold fungicides. Also trichodermin has a effect against gray mold. Rapamycin and trichodermin are biological pesticides, so they can be used in disease prevention on Dendrobium officinale preferentially.(2) The measurement of Dendrobium officinale plantlets and field seedlings show that Piriformospora indica can promote the growth of Dendrobium officinale. After Dendrobium officinale plantlets inoculated with Piriformospora indica for60days, the plantlets have more tillers and the average increase on the number of lateral buds is6.2, while the average increase on the number of lateral buds of the control group is only2.1, it indicates that Piriformospora indica promote the differentiation of Dendrobium officinale buds. Dendrobium officinale plantlets inoculated with Piriformospora indica have green stems, young and fresh leaf and they can grow better than the control group significantly, the fresh weight growth rate is109.43%,18%higher than the control group. Preliminary results show that Piriformospora indica can increase growth of Dendrobium officinale and also contribute to the germination and growth of Dendrobium officinale lateral buds. In addition, on the basis of the life history of Piriformospora indica, using a variety of cell wall degrading enzymes to crack Piriformospora indica spore walls and finally gain the method of lywallzyme efficient cleavage to crack Piriformospora indica, finally the protoplast of Piriformospora indica concentration up to7.55×107-17.71×107/ml, and make a foundation of building the Piriformospora indica genetic transformation system, Dendrobium officinale root colonization by Piriformospora indica and the research of molecular biology.