Pathogenicity of Klebsiella pneumonia(KpC4)infecting maize and mice

Recently, a new bacterial top rot disease of maize has frequently appeared in many areas of Yunnan Province, China. The pathogen of the disease was identified as Klebsiella pneumoniae （KpC4）, which is well known to cause pulmonary and urinary diseases in humans and animals and occasionally exists as a harmless endophyte in plants. To evaluate the viru- lence of the maize pathogen to maize and mice, we inoculated maize and mice with routine inoculation and intraperitoneal injection respectively according to Koch＇s postulates. The results showed that KpC4 and the clinical strain K. pneumoniae 138 （Kp138） were all highly pathogenic to maize and mice and the strain re-isolated from diseased mice also caused typical top rot symptoms on maize by artificial inoculation. It is highlighting that a seemingly dedicated human/animal pathogen could cause plant disease. This is the first report of K. pneumoniae, an opportunistic pathogen of human/animal, could infect maize and mice. The findings serve as an alert to plant, medical and veterinarian scientists regarding a potentially dangerous bacterial pathogen infecting both plants and animals/humans. The maize plants in the field could serve as a reservoir for K. pneumoniae which might infect animals and probably humans when conditions are favorable. The new findings not only are significant in the developing control strategy for the new disease in Yunnan, but also serve as a starting point for further studies on the mechanism of pathogenesis and epidemiology of K. pneumoniae.

Comparison of PCR, DIA and Pathogenicity Assay for Detection of Xanthomonas axonopodis pv.citri,the Causal Agent of Citrus Bacterial Canker Disease

Polymerase chain reaction (PCR) approach based on newly designed primers, JYF5/JYR5, wasapplied for specific detection of Xanthomonas axonopodis pv.citri(Xac). The efficiencyand reliability of PCR method were compared with dot immunobinding assay (DIA) andclassical pathogenicity test techniques for detecting suspensions of pure cells of Xacand soaking sap of citrus tissues. Detection sensitivity of PCR was about 4.5 cells or1.56 pg target DNA per reaction which was higher than that of DIA (ca. 450 cells per dot).These three techniques (PCR assay, DIA and Pathogenecity test) could always detect Xacfrom symptomatic citrus samples. Different performances were obtained from citrusmaterials without symptoms, and the positive detection frequency was PCR, DIA andpathogenicity test.

Isolation and Identification of a High-pathogenicity Strepto- coccus suis Serotype 7 Strain

In order to diagnose the diseased pigs in a certain large pig farm in Binzhou City, Shandong Province, the dead piglets with joint swelling were subjected to necroscopy, and the pathogenic bacterium was isolated and identified. One Gram-positive Streptococcus was isolated. The strain was subjected to characteristic culture, microscopic examination and molecular biological identification, and resistance detection, animal regression experiment and mouse pathogenicity test were carried out. The results showed that the isolate was identified to be Streptococcus suis serotype 7, which was resistant to multiple drugs; and the pathogenicity test showed that the strain had high pathogenicity to pigs, resulting in neurosis on partial pigs, and the strain had no pathogenicity to Kunming and BALB/c mice but certain pathogenicity to CD1 mice.

Morphological and molecular identification of Neopestalotiopsis clavispora causing flower blight on Anthurium andraeanum in Thailand

Flower blight on anthurium(Anthurium andraeanum)was observed during August 2018 on an anthurium cultivation farm in the Songkhla Province of southern Thailand.The fungal isolate was identified as Neopestalotiopsis clavispora based on the morphology and DNA sequence of the internal transcribed spacer(ITS),translation elongation factor 1-α(tef1-α),andβ-tubulin(tub)genes.The phylogenetic tree,based on the combined sequences of ITS,tef1-α,and tub,confirmed this pathogen as N.clavispora.Pathogenicity of the species was confirmed according to Koch’s postulate:N.clavispora could infect anthurium.To the best of our knowledge,this is the first report of N.clavispora as a pathogen of anthurium.

Ophiostomatales (Ascomycota) associated with Tomicus species in southwestern China with an emphasis on Ophiostoma canum

Ophiostomatalean fungi may facilitate bark beetle colonization and reproduction.In the present study of the fungal community associated with bark beetle species belonging to Tomicus in Yunnan,China,six ophiostomatalean fungi(Ophiostoma canum,O.ips,O.tingens,Leptographium yunnanense,Leptographium sp.1 and Leptographium sp.2)were isolated from the beetles or their galleries;O.canum was the most common fungal species.The distribution of O.canum was associated with stands heavily damaged by Tomicus species and a higher percentage of valid galleries of Tomicus yunnanensis and T.minor in Yunnan pine(Pinus yunnanensis).After inoculation of Yunnan pine with the fungus,a phloem reaction zone formed and monoterpenes accumulated in the phloem.These results suggested that O.canum was pathogenic to Yunnan pine and that the wide distribution of the fungus might be benefi cial to reproduction of pine shoot beetles in Yunnan pine.However,because the reaction zone and monoterpene accumulation were mild,fungal damage of Yunnan pine might be limited.A more integrated study considering all the fungal species should be done to better understand the interactions among bark beetles,blue-stain fungi,and the tree hosts in the region.

Wilt of Acer negundo L.caused by Fusarium nirenbergiae in China

Boxelder maple(Acer negundo L.)is widely grown as ornamental trees in China.In 2017 in Pizhou,Jiangsu Province,China,the boxelder maple trees suffered from a disease which caused wilting and yellowing leaves,rotted roots,and discolored xylem.The disease broke out from July to August.Seven fungal isolates were obtained from symptomatic tissue and tested for pathogenicity.Isolate An7 was isolated at high frequency from the discolored vascular tissues,which caused the wilt disease on healthy 2-year-old seedlings after inoculation and eventually killed all the seedlings.We conducted molecular analysis for An7,including the partial sequences of the rDNA internal transcribed spacer,calmodulin,RNA polymerase II second largest subunit and the translation elongation factor 1-αand evaluation of the variously sized conidia,chlamydospores and conidiophores and cultural traits.The pathogen was identified as Fusarium nirenbergiae,a member of the Fusarium oxysporum species complex.To our knowledge,this is the first report of F.nirenbergiae causing wilt on A.negundo in China.

八仙花叶斑病病原的分离与鉴定

八仙花[Hydrangea macrophylla (Thunb.)Ser.],又名绣球花、粉团花等,在城市现代公园和风景区建设中占据重要地位。八仙花在生长期常受到多种病原物危害,其中叶斑病发生普遍,病原种类复杂。已报道病原包括短小茎点霉(Phoma exigua)、交链格孢(Alternaria alternata)、极细枝孢(Cladosporium tenuissimum)、多主棒孢(Corynespora cassiicola)等[1-4]。2021年8月课题组在北京市丰台区发现八仙花叶斑病为害严重。

山东省葡萄白腐病病原菌鉴定

葡萄白腐病是世界范围内葡萄种植区的重要病害,每年可导致葡萄减产20%~30%[1-2],该病的病原菌有Coniella diplodiella (Speg.) Petrak & Sydow、C. fragariae (Oudem) B. Sutton、Pilidiella castaneicola和C. vitis[3-7]。1999年,LIU等[1]通过形态学研究明确了我国白腐病的病原为C. dip-lodiella。

Resolving the Colletotrichum siamense species complex using ApMat marker

Colletotrichum gloeosporioides sensu lato has been associated with anthracnose in diverse commercial crops.It is now established that C.gloeosporioides sensu lato comprises 33 phylogenetic species and C.gloeosporioides sensu stricto is not a common pathogen of tropical fruits.In this study,we investigated the phylogenetic relationships of 85 Colletotrichum isolates associated with select tropical fruits and flowering plants from India.In the ApMat marker analysis,the 85 isolates clustered with 7 known Colletotrichum species(C.aotearoa,C.dianesei,C.endomangiferae,C.musae,C.siamense,C.theobromicola,Glomerella cingulata f.sp.camelliae)and six novel lineages.One of the novel lineages is described and illustrated in this paper as Colletotrichum communis sp.nov.,while new-host pathogen associations for C.aotearoa,C.endomangiferae,C.dianesei and C.theobromicola are reported from India.Out of the 85 isolates analysed in this paper,73 isolates clustered within the C.siamense species complex,indicating that C.siamense species complex,not C.gloeosporioides sensu stricto,is common on tropical fruits.In comparison with act,cal,gapdh,ITS and tub2 gene markers,we recommend the use of the ApMat marker for accurate identification of cryptic species within the C.siamense species complex.We believe that the ApMat marker,in combination with one or two similar‘phylogenetically superior’gene markers,is a better candidate for specieslevel classification of fungi that were traditionally identified as‘Colletotrichum gloeosporioides’.