| Macleaya cordata(Willd)R.Br is a perennial herb which belongs to the genus Papaveraceae.The main active ingredient is isoquinoline alkaloids,including sanguinarine(SAN)and protopine(Protopine,PRO),Allocryptopine(ALL),Chelerythrine(CHE),etc.,which have good effects on regulating intestinal tract,antibacterial,anti-inflammatory and growth-promoting.M.cordata extract has developed as two class II of new Chinese veterinary drugs,and was exported to 45 countries and regions around the world as a natural-source anti-antibiotic product.With the European Union,United States,China and other major countries and regions in the world entering the "post-antibiotic era",the demand for M.cordata extract will increase sharply in the future.M.cordata resources were mainly derived from wild resources,with the expansion of market demand,wild resources decreased sharply.Conversion of wild resources into artificial cultivation was an important way to solve the problems of resource shortages.With the expansion of M.cordata planting scale,many planting bases frequently have disease problems.Diseases caused by fungal infections were an important factor affecting the production of M.cordata.Therefore,we investigated the types of fungal diseases on M.cordata in Hunan Province,and carried out morphological and molecular biological to identificate of the pathogens,identified three new diseases.Then we researched the environmental adaptability of pathogens and the differences in rhizosphere soil microbial communities.Finally,we screened effective chemicals and biocontrol fungi for indoor bacteriostasis of pathogen.The results are as follows:1.The results of the investigation of the fungal diseases of M.cordata: through a two-year investigation,we have preliminarily determined that the fungal diseases of M.cordata in Hunan Province mainly include root rot,stem rot,and leaf spot,while root rot was the most common occurrence.Root rot occurred concentratedly from June to September,with an incidence of 1.5% to 39.42%,showing two peak periods.The first peak period was from early June to early July,the rhizome produced white-pink or off-white hyphae after the onset.The second peak period occured from mid-July to September,with white silk flowers entwined on the rhizome.Stem rot occured mainly in March to May,with an incidence rate of 3.0-21.2%.In the later stage of the disease,he stem rotted and falled,then produced white hyphae and black sclerotia.There were two symptoms of leaf spot disease: one was the appearance of grayish-brown spots on the back of the leaves,which gradually expands and extends to the front,forming dark brown spots,and later the whole leaves appear necrosis.The leaves produced light yellow spots,which expanded into dark brown spots in the later stage,and finally the whole leaves wither and fall off.2.The identification results of the pathogens of the fungal diseases of M.cordata:according to the results of pathogenicity determination,combined morphological characteristics and multi-gene sequence analysis,we identified that Fusarium oxysporum and Fusarium fujikuroi were the pathogens of root rot in first stage and Athelia rolfsii as the pathogen of root rot in the second stage.Sclerotinia sclerotiorum was the pathogen of stem rot.Colletotrichum fructicola and Colletotrichum siamense were the pathogens of anthracnose leaf spot,among which Colletotrichum fructicola was the main pathogen.Alternaria alternata and Alternaria tenuissima were the pathogens of black spot leaf spot,and Alternaria tenuissima was the main pathogen.3.The main biological characteristics of root rot pathogen on M.cordata: the pathogen growed best at 25 ? or 30 ?.Light and darkness have no significant effect on the growth of hyphae,but have an effect on the formation of sclerotia and spores.Half-light was beneficial for the formation of sclerotia or conidia of pathogenic bacteria.The minimum lethal temperature of hyphae,sclerotia or conidia of three pathogens was?52 ?.Neutral or acidic conditions were suitable for the growth of pathogens.4.Characteristics of microbial community structure in the rhizosphere soil: select the rhizosphere soil of M.cordata as the research samples,and compare and analyze the microbial community structure of the healthy and root rot rhizosphere soil,and the fungal community in the rhizosphere soil features were as follows:(1)After infection,the fungal alpha diversity of M.cordata rhizosphere soil decreased,and the fungal alpha diversity can be used as a biological indicator of the occurrence of M.cordata root rot.(2)The fungal community of root rot and healthy rhizosphere soil fungi were divided into two branches.The occurrence of root rot was the main factor that affected the difference in the structure of the fungal community in the rhizosphere soil.(3)The increase of potential pathogenic fungi(such as Fusarium and Neocosmospora)in infected samples was one of the reasons why the rhizosphere microbial environment has changed from "healthy" to "disease".(4)The total potassium content in the rhizosphere soil was positively correlated with the fungal community in the healthy rhizosphere soil.The bacterial communities in the rhizosphere soils of healthy and root rot diseases showed that:(1)The alpha diversity of soil rhizosphere bacteria decreased in areas with high disease index after M.cordata was infected root rot,and it can be used as a biological indicator to judge the severity of the disease.(2)The bacterial communities in the rhizosphere soil in different regions were divided into two branches.Spatial factor was the main factor affecting the differences in the bacterial community structure in the rhizosphere soil.(3)In the rhizosphere soil of low-incidence areas,pathogenic bacteria groups such as Chitinophaga sp.and Flavobacterium sp.appeared,and the rhizosphere soil of high-incidence areas were enriched potential pathogenic bacteria such as Pseudomonas sp..(4)The total potassium content in the rhizosphere soil was positively related to the bacterial community in the healthy rhizosphere of M.cordata.5.Continue the screening of chemical reagents and biocontrol fungi for the pathogenic S.rolfsii,we screened Tebuconazole,Amomi,Amisida and Kairun·Zyproxil had good inhibitory effect on the mycelial growth and sclerotia formation to pathogen.At the same time,a biocontrol fungus BLH-G1 that had an inhibitory effect on the growth of pathogen was screened,according to morphological and biological identification,the isolate BLH-G1 was Trichoderma virens.These reaseach provided guidance for the field control on M.cordata. |
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