Lanzhou lily (Lilium davidii var. willmottiae) is an exclusive sweet lily variety indigenous to China, which is susceptible to bulbous rot caused by fungal infection during storage. This experiment tests the pathogenicity of the pure culture isolated from the diseased tissue was confirmed in accordance with Koch's postulates, and the pathomycetes were identified based on their morphological and molecular characteristics. Furthermore, the biological characteristics of the pathogens were investigated, followed by an evaluation of the antifungal effects of three plant essential oils against them. The results showed that two strains of fungi were isolated from Lanzhou lily rot, which were identified as Fusarium oxysporum Schl. and Aspergillus sydowii (Bain. Et sart.). In addition, the pathogenicity of these two strains of fungi was demonstrated that only F. oxysporum induced rot with similar symptoms during the post-harvest storage period. The biological characteristics of F. oxysporum indicated the potato maltose agar and lily dextrose agar were identified as the most suitable media. Sucrose was determined to be the optimal carbon source, while ammonium nitrate was found to be the best nitrogen source for the growth of F. oxysporum. Mycelial growth and sporulation of F. oxysporum occurred at an optimum pH value of 6. Total darkness facilitated mycelial growth and conidial germination. The ideal temperature for growth was found to be 28°C, while relative humidity did not significantly impact mycelial growth; however, a relative humidity of 55% was most favorable for spore production. Among the three essential oils tested, cinnamon essential oil displayed superior antifungal efficacy against F. oxysporum, whereas angelica essential oil and tea tree essential oil also exhibited moderate inhibitory effects against this pathogen. This research provides valuable theoretical insights for disease control during the storage and transportation of Lanzhou lily.

为明确甘肃省民乐县采集的藜霜霉病病原菌的种类,文章对其进行常规形态学鉴定,提取了菌物的DNA,利用cox1、cox2-mtDNA和ITS rDNA基因序列进行分子鉴定,并构建了系统发育树,以明确其分类地位.形态学鉴定结果和基于cox1、cox2、ITS序列的系统发育树均表明该病原菌为藜麦霜霉菌Peronospora variabilis.

Objective: To identify the pathogen causing bacterial leaf spot of Astragalus membranaceus in Gansu province and lay a foundation for the prevention and control of this disease. Methods: The pathogen was identified based on the morphological, physiological, and biochemical characteristics and the phylogenetic tree constructed based on 16S rDNA,rpoB, and rpoD. Results: The pathogen colony on NA medium appeared round or nearly round, milky white, smooth,convex, and translucent, with entire margin and the diameter of 1-3 mm. It is an aerobic Gram-negative bacterium which can grow at 10-40 ℃, pH 5.7 and 6.8. The pathogen can tolerate 2% and 5% NaCl, while it cannot grow in the medium with 7%or 10% NaCl. It can utilize glucose, xylose, mannose, citrate, and nitrate and produce tyrosinase, catalase, and phenylalanine deaminase. It can decompose tryptophan, liquefy gelatin, and cannot produce lecithinase, starch hydrolase, or acetylmethylcarbinol. The pathogenicity test preliminarily verified the isolated bacterium was the pathogen causing bacterial leaf spot of A. membranaceus. The sequence analysis of 16S rDNA, rpoB, and rpoD further identified the pathogen as Pseudomonas viridiflava（Burkholder） Dowson. Conclusion: This study provides a theoretical basis for the prevention and treatment of bacterial leaf spot of A. membranaceus.

[目的]通过研究甘肃省13种大宗药用植物内生细菌促生及拮抗特性,为筛选药用植物内生细菌中的优势促生、拮抗菌资源奠定基础.[方法]以甘肃省13种大宗药用植物为材料,采用常规的稀释涂布平板法分离内生细菌,明确其数量及分布特点;通过固氮、解磷、产吲哚乙酸(IAA)等指标初步检测内生细菌的促生能力;采用平板对峙法,测定内生细菌对6种植物病原真菌的拮抗能力.[结果]共分离获得439株内生细菌,内生细菌的分布依次为根(48.06％)＞茎(29.38％)＞叶(22.56％),不同组织中,根中菌群密度最大,为2.18×104～5.58×104cfu/g;茎次之,为1.58×104～4.38×104 cfu/g,叶中最小,为0.80×104～3.48×104 cfu/g;184株具固氮活性(41.91％),GCG16的固氮能力最强;48株溶磷细菌(10.93％),溶磷量在2.85～49.37 mg/L之间,KDY9的溶磷能力最强;287株具分泌IAA能力(58.10％),产IAA量在5.49～56.38 mg/L之间的菌株有44株,DSG7的产IAA能力最强;16株具有抑菌能力(3.64％),抑菌率在18.74％～53.01％之间,KSG7对尖孢镰刀菌的抑菌能力最强.[结论]甘肃省药用植物内生细菌种类丰富,DSG3、CHG4、KDG5、KDG4等具有优良拮抗和促生能力.

Chinese rhubarb (Rheum palmatum) is an important crop that has been used in traditional Chinese medicine for over 2,000 years. The main cultivation areas are the Chinese provinces of Gansu, Qinhai, Tibet, and Sichuan. Various fungal diseases threaten Chinese rhubarb, the most common of which is leaf smut. In literature, the causal agent of this disease is described as Thecaphora schwarzmaniana. We present morphological data and molecular phylogenetic data of two rDNA loci (ITS1-5.8S-ITS2 and 28S D1-D2) that justify the classification of the causal agent as a distinct species. Here we describe the new species Thecaphora dahuangis for the leaf smut pathogen of Chinese rhubarb.

A new leaf spot disease was observed on leaves of Rheum palmatum (Chinese rhubarb) in Northwest China (Gansu Province) starting in 2005. A Septoria-like fungus was isolated and completion of Koch's postulates confirmed that the fungus was the casual agent of the leaf spot disease. Morphology and molecular methods were combined to identify the pathogen. The fungus produced conidiomata pycnidia and the conidia were 2~5 septate, 61.2~134.1 µm in length and 3.53~5.3 µm in width, which is much larger than the known Spetoria species that infects Polygonaceae species. Phylogenic analysis of the internal transcribed spacer region confirmed that this Spetoria-like fungus is within the Spetoria genus but distinct from known Spetoria species. Together, these morphological and phylogenetic data support that the R. palmatum infecting Spetoria strain is a newly-described plant pathogenic species.

Gray mold on Anemarrhena asphodeloides and Aster tataricus caused by Botrytis cinerea are reported for the first time in China. The diseases lead to leaf lesion and plant blight. Based on morphology characteristics and rDNA internal transcribed spacer sequence analysis, the two fungi were identified as B. cinerea.

OBJECTIVE:To investigate diseases occurring in Rheum palmatum in Gansu province and identify pathogen.METHOD:Field survey in the main R. palmatum producing area and the pathogens were identified on the base of morphology.RESULT:Eight fungal diseases have been found after disease surveys on R. palmatum in Gansu province from 2004 to 2007. They were leaf smut (Thecaphora schwarzmaniana), leaf spot (Septoria sp.), rust (Puccinia rheipalmati), ring spot (Ascochyta rhei), powdery mildew (Erysiphe polygoni.), grey mold (Botrytis sp.), root rot(Fusarium oxyxporium) and a virus disease.CONCLUSION:Leaf smut, a severe disease with the incidence of 14%-26%, is the urgent problem waiting to be solved effectively. Powdery mildew and grey mold were reported for the first time in China.