茄青枯病菌引起的新病害-罗汉果青枯病

 罗汉果为葫芦科(Cucurbitaceae)罗汉果属[Siraitia grosvenorii(Swingle) C.Jeffrey]植物。罗汉果中含有0.8%~1.0%的罗汉果甜甙,其甜度为蔗糖的300倍,是肥胖症、高血压、高血脂、糖尿病等患者最理想的甜味剂与保健品。罗汉果甜贰远销美国、日本等国外市场,产品供不应求。     

A new bacterial leaf blight disease of oat (Avena sativa) caused by Pantoea agglomerans in China

A new leaf blight disease of oat (Avena sativa) was observed in many oat fields in Huan county, Gansu Province of China, during 2018–2019. Typical symptoms appeared as yellow necrotic and water-soaked lesions. The lesions developed from tip to base of leaves and eventually resulted in leaf withering. Disease incidence on plants (leaves) was approximately 36%–100%. A gram-negative bacterium was isolated from the necrotic lesions of all samples. Coupled with multigene sequence (16S rRNA and gyrB gene) analyses, Biolog Gen III MicroStation, morphological, physiological, and biochemical characterization identified the pathogen as Pantoea agglomerans. Pathogenicity tests by wounding and injection inoculations in the greenhouse established that P. agglomerans could induce typical symptoms as observed in the field. The infection rate in leaves was 44%–71% after 14 days. In addition, host range tests showed that P. agglomerans could infect other plant hosts, including Sorghum sudanense, Medicago sativa, Fagopyrum esculentum, Setaria italica, and Zea mays. This is the first report of P. agglomerans causing bacterial leaf blight disease (LBD) on oat in China. The current study can provide a foundation for the prevention of this disease in the future.     

Occurrence of bacterial rot of onion bulbs caused by Burkholderia cepacia in Japan

In 2001, a bacterial rot of onion (Allium cepa L.) bulbs was observed in Japan. The causal agent was identified as Bukholderia cepacia (Palleroni & Holmes 1981 ex Burhkolder 1950) Yabuuchi, Kosako, Oyaizu, Yano, Hotta, Ezaki, and Arakawa 1993. The identified bacteria were divided into two groups (Y and W) based on colony colors, and several phenotypic and genetic characteristics. Based on recA polymerase chain reaction assays, the strains of the Y and W groups belong to genomovar I (B. cepacia sensu stricto) and genomovar III (B. cenocepacia), respectively.The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession numbers AB162427 and AB162428     

Leaf blight and defoliation caused by two new pathovars of Xanthomonas axonopodis on Schinus terebinthifolius and Mabea fistulifera

Schinus terebinthifolius and Mabea fistulifera have been used for forest repositioning and urban forestry in Brazil. In October 2012, in a routine inspection at the research nursery of the Forestry Department of the Universidade Federal de Viçosa, in Minas Gerais, Brazil, a mortality of approximately 40% of the seedlings was observed as a result of diseases characterized by leaf blight and intense defoliation, which culminated in the death of the plants. Microscopy observations revealed oozing from the infected tissue and isolations revealed a bacterial aetiology for both diseases. Bacterial cells that formed bright yellow mucoid colonies with round edges were routinely isolated from lesion margins. Inoculation of isolated strains into healthy seedlings reproduced the symptoms observed under natural conditions. Bacterial cells showing the same morphological, biochemical and molecular characteristics as those originally isolated from naturally infected plants were reisolated from inoculated plants. Morphological, physiological and biochemical tests as well as 16S rDNA sequencing and multilocus sequence analysis using four housekeeping genes, dnaK, fyuA, gyrB and rpoD, confirmed the newly isolated strains belong to Xanthomonas axonopodis. Plant cross‐inoculations showed the strains did not belong to any known phylogenetically related pathovar. Pathovars X. axonopodis pv. schini pv. nov. and X. axonopodis pv. mabeae pv. nov. are proposed as the causal agents of bacterial leaf blight on S. terebinthifolius and M. fistulifera, respectively.     

A new disease of cardamom (Elettaria cardamomum) caused by Erwinia chrysanthemi in Papua New Guinea

A serious disease of cardamom in East New Britain Province of Papua New Guinea was shown by pathogenicity and biochemical tests to be caused by Erwinia chrysanthemi. The bacterium was repeatedly isolated from blackened roots, soft discoloured rhizome tissue and rhizosphere soil, but not from field soil in the immediate neighbourhood of diseased plants.     

Notes on the apterae viviparae of Pentalonia gavarri Eastop (Homoptera,Aphididae)

Abstract

Apterae viviparae of Pentalonia gavarri are recorded for the first time, on graminaceous hosts in West Malaysia. Keys are presented for the separation of P. gavarri and nigronervosa, based upon both apterae and alatae.     

A new disease of greenhouse tomatoes in Israel caused by a distinct strain ofTomato apical stunt viroid (TASVd)

Using the sequential PAGE method for detection of small circular RNA molecules we isolated a viroid from greenhouse-grown tomato plants exhibiting severe stunting in Israel. The viroid was transmitted to tomato and to several other solanaceous plants by graft and mechanical inoculation, but only tomato plants showed symptoms of disease. Cloning and sequencing revealed that the viroid RNA is composed of 363 nucleotides, has 92% identity with the type strain (Ivory Coast strain) ofTomato apical stunt viroid (TASVd) and 99% identity with the Indonesian strain of this viroid. The experimental host range of TASVd-Is differs significantly from that of the type strain of TASVd. The possible epidemiological consequences leading to TASVd spread in geographically distant areas are discussed. http://www.phytoparasitica.org posting Sept. 18, 2002. Corresponding author     

A new aubergine disease caused by a whitefly‐borne strain of Tomato mild mottle virus (TomMMoV)

The aims of the present study were to further characterize the causal agent of a new viral disease of aubergines in Israel, first observed in 2003 and tentatively named eggplant mild leaf mottle virus (EMLMV) in a previous work, and to identify the vector responsible for its spread. The disease could be transmitted mechanically from infected source plants to healthy aubergines or laboratory test plants. Transmission electron microscopy (TEM) analysis of purified virus preparations indicated the presence of viral particles with a flexible filamentous morphology (approximately 720 nm long). TEM analysis of ultrathin sections prepared from infected leaf tissue revealed the presence of cytoplasmic inclusion bodies with pinwheel and crystalline structures, typical of those induced by potyviral infection. The viral coat protein subunit was shown to have a molecular weight of 37·5 kDa by SDS‐PAGE analysis. The viral particles reacted positively in western blot analysis with an antiserum against Tomato mild mottle virus (TomMMoV) from Yemen, described as a potyvirus, vectored by the aphid Myzus persicae. The current study describes some biological properties of EMLMV and presents evidence for its transmission by the whitefly Bemisia tabaci, but not by three aphid species. The taxonomic relationship between EMLMV and TomMMoV is discussed based on their biological characteristics and sequence analysis of their genomes. It is suggested that the Israeli EMLMV should be considered a distant strain of TomMMoV, designated TomMMoV‐IL, according to the present rules of Potyviridae molecular taxonomy.     

A new selective medium for Burkholderia caryophylli, the causal agent of carnation bacterial wilt

A new selective medium (APCA medium) was developed for the isolation of Burkholderia caryophylli , the causal agent of carnation bacterial wilt, from both plants and soil. The optimal concentration and combination of antibiotics was investigated to determine the most selective condition for growing B .  caryophylli . The resultant composition of the medium per litre was: 0·79 g (NH₄)₂SO₄, 1·0 g KH₂PO₄, 0·5 g MgSO₄ · 7H₂O, 0·2 g KCl, 2·0 g D-arabinose, 5 mg crystal violet, 50 mg cycloheximide, 50 mg polymyxin B sulphate, 50 mg ampicillin sodium, 10 mg chloramphenicol, 25 mg blue tetrazolium, and 15 g agar. Plating efficiency ranged from 119 to 174% with an average of 141% compared to that of nutrient agar. The bacterium was successfully isolated from contaminated soil and plant tissues with this medium. Moreover, the medium almost completely inhibited the growth of other plant pathogenic bacteria and soil saprophytes. This selectivity was high enough to detect B . caryophylli in contaminated soil.     

Bacterial pathogens of rice in the Kingdom of Cambodia and description of a new pathogen causing a serious sheath rot disease

A study of rice diseases in Cambodia from 2005 to 2007 showed widespread occurrence of diseases caused by Acidovorax avenae subsp. avenae, Burkholderia gladioli, B. cepacia and Pantoea ananatis. This is the first report of these pathogens in Cambodia. Additionally, a pseudomonad causing a widespread disease similar to sheath brown rot (caused by Pseudomonas fuscovaginae) was isolated. The studied strains were pathogenic to rice cvs Sen Pidau and IR 66, producing similar, though slightly less severe, symptoms to those observed in the field. Based on comparative 16S rDNA gene sequence analysis, combined with cell wall fatty acid analysis and metabolic profiles, the isolated strains were allocated to the genus Pseudomonas. The novel species were differentiated from Pseudomonas fuscovaginae and P. putida by their inability to metabolize d ‐fructose, d ‐galactose, d ‐galactonic acid lactone, d ‐galacturonic acid, d ‐glucosaminic acid, d ‐glucuronic acid, p‐hydroxy phenylacetic acid, d ‐saccharic acid and urocanic acid. The major fatty acids were C_16:0, summed feature 3 (C_16:1ω7c and C_16:1ω6c) and summed feature 8 (C_18:1ω7c), representing 80% of the total. Partial 16S rRNA gene sequences (1460 bp) were identical, except for two nucleotide changes amongst the six strains. Alignment of the causal strains within type‐culture databases revealed similarities of 99·7% with Pseudomonas parafulva AJ 2129^T, 99·2% with P. fulva IAM 1592^T, 98·9% with P. plecoglossicidia FPC 951^T, and 98·1% with P. fuscovaginae MAFF 301177^T. On the basis of data from this polyphasic study, it is proposed that the unknown strains isolated from rice represent a novel species of the genus Pseudomonas.     

A new anthracnose disease of pyrethrum caused by Colletotrichum tanaceti sp. nov

A new pathogen of pyrethrum (Tanacetum cinerariifolium) causing anthracnose was described as Colletotrichum tanaceti based on morphological characteristics and a four‐gene phylogeny consisting of rDNA‐ITS, β‐tubulin (TUB2), glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) and actin (ACT) gene sequences. The fungus produced perithecia in culture, requiring an opposite mating type isolate in a heterothallic manner. The initial infection strategy on pyrethrum leaves involved the formation of appressoria followed by production of multilobed infection vesicles in the epidermal cells. Infection and colonization then proceeded through thinner secondary hyphae, which resulted in the initial production of water‐soaked lesions followed by black necrotic lesions. The infection process was suggestive of a hemibiotrophic infection strategy. Moreover, phylogenetic analysis clearly showed that C. destructivum, C. higginsianum and C. panacicola were separate species that also had similar intracellular hemibiotrophic infection strategies as C. tanaceti, which all clustered in the C. destructivum complex. Colletotrichum spp. were detected at 1% incidence in seed of 1 of 19 seed lines, indicating the potential for seed as a source of inoculum into crops. Colletotrichum tanaceti was detected in leaf lesions from 11 of 24 pyrethrum fields surveyed between April and July 2012, at a frequency of 1·3–25·0% of lesions. Anthracnose probably contributes to the complex of foliar diseases reducing green leaf area in pyrethrum fields in Australia.     

A new leaf spot disease of Cuphea spp. caused by Chaetomella raphigera

A new leaf spot disease of Cuphea spp., an emerging oilseed crop, was observed in the experimental fields of the National Botanical Research Institute, Lucknow, India. The pathogen was isolated and identified as Chaetomella raphigera.     

Two new records of downy mildews (Peronosporaceae) in Turkey and a new host

Peronospora crucianellae Maire onCrucianella latifolia L. andPeronospora trifolii-arvensis Syd. onTrifolium sp. were collected for the first time in Turkey. The plant speciesSinapis arvensis L. is reported as a new host forPeronospora brassicae Gäum. from Turkey. The peronosporaceous fungi recorded since the beginning of microfungal studies from Turkey are given along with their collection sites.     

一种由可可毛色二孢引起的春芋新病害

正可可毛色二孢(Lasiodiplodia theobromae(Pat.) GriffonMaubl.)是由Griffon和Maublanc~([1])在对Botryodiplodia theobromae进行订正的基础上而确立,Alves等~([2])于2008年对这个种又进行了研究并补充了DNA序列信息。可可毛色二孢是一种重要的病原菌,可引起多种植物的枯萎、根腐及焦枯等病害症状~([3,4])。而假可可毛色二     

Field evaluation of treatments for the control of the bacterial apical necrosis of mango (Mangifera indica) caused by Pseudomonas syringae pv. syringae

Bacterial apical necrosis is a critical disease in the main production area of mango in Europe. It is caused by Pseudomonas syringae pv. syringae, and produces necrotic lesions on mango buds and leaves, causing severe yield losses due to a decrease of flowering and fruit set. A field study to evaluate control treatments against bacterial apical necrosis was carried out during three seasons on mango trees cv. Tommy Atkins in Huelva (Spain). Experimental treatments included Bordeaux mixture, fosetyl-Al, acibenzolar-s-methyl, gibberelic acid, silicon gel, a mixture between acibenzolar-S-methyl and Bordeaux mixture, and combined applications of fosetyl-Al with Bordeaux mixture or silicon gel. The treatments which caused a consistent reduction in bacterial apical necrosis symptoms at similar levels to the conventional treatment with Bordeaux mixture, were the plant resistance activator acibenzolar-S-methyl and the phosphonate derivative fosetyl-Al applied singly or in combination with other compounds, which could be alternative treatments. These treatments showed a significant decrease in the necrotic buds and/or leaves numbers; however, minor differences in P. syringae-like population levels were observed. The analysis of the inhibitory and bactericidal concentrations of cupric compounds against P. syringae strains isolated from mango tissues suggests that the commercial copper-based treatments with Bordeaux mixture used in the management of mango crops do not work in a bactericidal mode of action.     

A new disease of sorrel (Hibiscus sabdariffa var. sabdariffa) caused by Coniella musaiaensis var. hibisci from Trinidad and Tobago

A serious leaf spot and stem canker observed on Hibiscus sabdariffa var. sabdariffa is reported for the first time from Trinidad and Tobago. Symptoms are described and the pathogen is identified as Coniella musaiaensis Sutton var. hibisci .     

石蛃亚科——中国新纪录属和新纪录种（石蛃目：石蛃科）

记述石蛃亚科Machilinae——中国新纪录属、种,即韩蛃属Coreamachilis,高丽韩蛃Coreamachilis coreanus Mendes,1991,提供了该物种雌性形态结构图。研究标本保存在浙江师范大学生化学院生态研究所。     

Collar rot and wilt: a new disease of Java citronella (Cymbopogon winterianus) caused by Fusarium moniliforme Sheldon

Commercial plantations of Java citronella ( Cymbopogon winterianus ) in Lucknow, Pantnagar and their adjoining areas were affected by a collar rot and wilt disease. The causal organism was identified as Fusarium moniliforme , anamorph of Gibberella fujikuroi. Isolates of the pathogen originating from Lucknow and Pantnagar differed in their pathogenicity on the host plant under glasshouse conditions. There were also differences in growth rates, pigment production and sporulation between isolates.     

A new yellowing disease of cucurbits caused by a luteovirus, cucurbit aphid-borne yellows virus

Since 1988, a yellowing disease of melon, cucumber and zucchini squash has been frequently observed in summer and autumn crops in France. Infected plants show yellowing and thickening of the older leaves; symptom intensity differs depending upon cultivar and season, and can be easily overlooked when plants are already infected by mosaic-inducing viruses or other pathogens. The disease is associated with the presence of a virus with spherical particles c. 25 nm in diameter, which is readily transmitted in a persistent manner by the aphids Myzus persicae and Aphis gossypii , but not mechanically. Serological analysis, nucleic-acid-hybridization experiments and host-range studies indicate that the virus is distantly related to, but distinct from, beet western yellows virus (BWYV). We propose to name this virus cucurbit aphid-borne yellows virus (CABYV), and to consider it as a tentative new member of the luteovirus group. CABYV was found to reduce significantly the yields of melon and cucumber by decreasing the number of fruit per plant but not by altering the fruit shape or quality. Preliminary investigations of the epidemiology of CABYV indicate that the virus is common in weeds and in cultivated cucurbits. CABYV was frequently detected in various regions of France, suggesting that it is one of the most prevalent viruses infecting cucurbits in this country.