The Astragalus membranaceus root rot disease,a soil-borne disease,has become increasingly severe in Shanxi province.This study was aimed at getting antagonistic Bacillus with excellent bio-control effects,and determining its effects on bacterial communities in root zone soil. With Fusarium solani and F. acuminatum as the target,antagonistic Bacillus was selected through such tests as living body dual culture,antifungal effect of bacteria-free filtrate,mycelia growth inhibition in vitro and control effect in detached roots,and identified with morphology,physio-biochemical characteristics and 16 S r DNA sequence analysis. The results showed that the Bacillus strain SXKF16-1 had obvious antifungal effect. The diameter of inhibition zone of its bacteria-free filtrate to F. solani and F. acuminatum was( 25. 90±1. 18) mm and( 25. 86±1. 85) mm respectively,and showed a lasting inhibition effect to mycelia growth. The disease index of the protective treatment and that of the cure treatment in detached roots test to F. solani and F. acuminatum were( 37. 50±8. 58),( 41. 67±4. 90) and( 25. 00±8. 33),( 38. 89±9. 62) respectively,both being significantly different( P<0. 05) from that of the control. The strain SXKF16-1 was identified as Bacillus atrophaeus. The B. atrophaeus SXKF16-1 showed significantly inhibition effect to pathogen causing root rot and could increase the bacterial diversity in root zone soil. It has potential to be developed as a special biocontrol agent.
Astragalus Plant/microbiology* ; Bacillus/physiology* ; Biological Control Agents ; Fusarium/pathogenicity* ; Plant Diseases/prevention & control* ; Plant Roots/microbiology* ; Soil Microbiology

OBJECTIVETo study difference among populations which belong to Astragalus membranaceus and A. membranaceus var. mongholicus on morphology, habit, characteristics of physiology and resistance to powdery mildew, and classify them in order to provide theoretical basis for breeding and improving varieties.

METHODMorphology, habits, isozyme and soluble protein electrophoretograms were compared among the populations. They were categorized by cluster analysis based on those electrophoretograms. Different ability of resistance to powdery mildew was also studied through comparing disease indices among six populations.

RESULTThe results showed A. membranaceus var. mongholicus was distinctly different from A. membranaceus. There was a special type in colonies of A. membranaceus, which showed hairy upper epidermis of leaflets and later florescence.

CONCLUSIONAstragalus for medicine could be categorized in three types A. membranaceus var. mongholicus, A. membranaceus early florescence type and A. membranaceus late florescence type. Among them A. membranaceus var. mongholicus is most resistant to powdery mildew, while A. membranaceus is easily infected, and the early florescence type is even more easily infected.

Ascomycota ; pathogenicity ; Astragalus Plant ; classification ; growth & development ; metabolism ; microbiology ; Astragalus membranaceus ; growth & development ; metabolism ; microbiology ; Peroxidase ; metabolism ; Phylogeny ; Plant Diseases ; microbiology ; Plant Proteins ; metabolism ; Plants, Medicinal ; classification ; growth & development ; metabolism ; microbiology

OBJECTIVETo control the medicinal plant diseases with the preparation of Trichoderma harzianum.

METHODAntagonistic action of the preparation to the pathogens of the medicinal plants in vitro, and controling effects of the preparation on these diseases in greenhouse and in the field were tested.

RESULTThe test in vitro showed that Trichoderma harzianum, used as a biocontrol factor, had stronger antagonistic action to Fusarium equiseti, Sclerotinia sp. and Rhizoctonia solani which were the medicinal plant pathogens of Astragalus membranaceus, Glehnia littoralis and Panax quinquefolium respectively. Biological controling effects on sclerotium root rot of Glehnia littoralis were 83.6% and 72.5% respectively in greenhouse and in the field with the preparation of Trichoderma harzianum. And controling effects on root rot of Astragalus membranaceus and seedling damping-off of Panax quinquefolium were 80% and 60% respectively in the field. The dosage of the preparation used in the field was 10 g.m-2.

CONCLUSIONThe preparation of Trichoderma harzianum can be used as a substitute for such chemicals as Carbendazim. Using the preparation to control medicinal plant diseases provides a technical safeguard for the good agricultural practice of medicinal plants.

Apiaceae ; growth & development ; microbiology ; Ascomycota ; pathogenicity ; Astragalus membranaceus ; growth & development ; microbiology ; Fusarium ; pathogenicity ; Panax ; growth & development ; microbiology ; Pest Control, Biological ; methods ; Plant Diseases ; microbiology ; Plant Roots ; microbiology ; Plants, Medicinal ; growth & development ; microbiology ; Rhizoctonia ; pathogenicity ; Soil Microbiology ; Trichoderma ; physiology

OBJECTIVETo study the culture-filtrate producing condition of Fusarium Solani isolated from Astragalus root and explore the mechanism Astragalus root rot disease caused by, in order to find theoretical support for screening resistant germ plasma via mycotoxin.

METHODThe method of germinating seeds in petri dish with filter paper and inhibition method for embryo growth were used to study the biological activity and the specialty of cultural filtrate of 10 F. solani isolates.

RESULTThe toxin produced by F. solani had strong inhibition effect in the different nutrient media, at different temperatures and under different light conditions. With extension of culturing time, embryo inhibition rate went up gradually with the strongest inhibition at the 12th day and the inhibition ratio between 92.0% -52.0%. The toxin produced at 5 degrees C to 35 degrees C inhibited embryo germination of Astragalus differently with the strongest at 25 degrees C, and next to it at 20,30 degrees C. The impact of light on bioactive substances of the toxin was not statistically distinctive, but the 24-hour darkness was benefit to toxin production. PSC had a stronger inhibition rate than the other nutrient media, next to it was PDB. After autoclaving, the toxin still kept toxic to embryo of Astragalus, which indicated that the toxin was tolerant to high temperatures.

CONCLUSIONThe toxin produced by F. solani at different growing condition had strong biological activity, was tolerant to high temperature. The best condition for F. solani to produce toxin was that it was cultured in PSC liquid medium, in dark, at 25 degrees C for 12 d. The toxin produced by isolate HQM40 was non-host specific toxin.

Astragalus Plant ; drug effects ; embryology ; microbiology ; Culture Media ; metabolism ; Culture Techniques ; Fusarium ; chemistry ; isolation & purification ; metabolism ; radiation effects ; Germination ; drug effects ; Light ; Mycotoxins ; chemistry ; metabolism ; toxicity ; Plant Diseases ; microbiology ; Plants ; drug effects ; embryology ; Seeds ; drug effects ; physiology