大豆种质对疫霉根腐病抗性特点研究

对1027份中国和国外引进的大豆种质进行了大豆疫霉(Phytophthora sojae)根腐病的抗病性鉴定评价.结果表明,中国大豆种质的抗病性高于国外引进种质;中国南方的大豆种质抗病性较北方种质强,长江流域大豆中抗病种质比率最高,其次为黄淮海流域种质,而东北地区抗病种质较少;不同省份大豆种质的总体抗病性差异明显;育成品系的抗性好于改良品种和农家种,但不同省份来源的农家种、品系和品种抗性存在差异,黑龙江材料抗病性最低,这也是该省大豆疫霉根腐病严重发生的重要原因之一;在大豆籽粒脐色为黄色和褐色的材料中,抗病种质较多.     

蓝莓腐霉根腐病的病原菌

在山东青岛新发现一种蓝莓根腐病害,症状最初出现在根部,病根腐烂坏死,根状茎维管束和皮层变黑,导致根数量减少,叶片变黄、变红,植株生长不良,严重时叶片全部脱落,植株死亡。通过组织分离法和菌丝段分离法获得纯化菌株HMQAU 180018,经柯赫氏法则验证,综合形态学特征及ITS区和cox I基因序列分析,菌株HMQAU 180018被鉴定为畸雌腐霉Pythium irregulare。这是国内首次描述畸雌腐霉引起蓝莓根腐病的报道。     

Leaf Stripe and Stem Rot Caused by Burkholderia gladioli,a New Maize Disease in Mexico

A disease in maize plants, not previously observed, appeared in 2003–2004 in Cosoleacaque, Tlalixcoyan and Paso de Ovejas counties, in the state of Veracruz, Mexico. Initial symptoms on leaves were small white‐yellow watery spots, which coalesced into dry necrotic stripes 0.3 wide and up to 8 cm long. Reddening sometimes developed on these leaves. Stems developed a rot in the crown. The flag leaf became rot and necrotic at the base, rolled inwards and dried out. Necrosis developed at the base of the corn ears and their growth was inhibited. These symptoms were initially observed in Asgrow‐7573 commercial maize plantings. A bacterium characterized by white colonies, gram negative, aerobic, rod‐shape, opaque, round colonies with entire margins on casaaminoacid peptone and glucose media was consistently isolated from diseased maize plants. On King’s Medium B, the isolates produced yellow, non‐mucoid colonies, with the majority of the strains secreting a diffusible yellow pigment into the media. The bacterium identity was confirmed by PCR amplification and sequencing of 16S and 23S genes rDNA fragments. The bacterium was identified as Burkholderia gladioli. Its pathogenicity on maize plants in Mexico is a new record.     

Characterization of Pseudomonas maltophilia Isolates from Fleece Rot

A total of 286 isolates of Pseudomonas maltophilia was collected from sheep exhibiting brown or yellowish fleece rot and from fly-strike lesions. Enzyme activities for 10 of the isolates were examined by plate tests and with the API ZYM system and compared with the enzymatic profile of a human type strain of P. maltophilia. The fact that ovine isolates of P. maltophilia are biochemically similar to pathogenic human strains suggests there may be an association between this organism and the brown to yellow type of fleece rot.     

Relationship between Ripening and the Development of Banana Anthracnose Caused by Colletotrichum musae (Berck. and Curt.) Arx

Wound anthracnose caused by Colletotrichum musae is the main disease affecting the quality of export bananas from the French Antilles. Little is known about the effects of ethylene on the development of wound anthracnose and quiescent anthracnose. The results of our experiments with 1‐methylcyclopropene (1‐MCP), an ethylene receptor site inhibitor, clearly revealed that ethylene was not directly involved in triggering rot development. Quiescent anthracnose symptoms were found to appear only after bananas began ripening. In contrast, wound anthracnose developed just as quickly in ‘green 1‐MCP‐treated bananas’ as in ‘yellow ripening bananas’. In cases of wound anthracnose, contrary to quiescent anthracnose, rot development was not dependent on the extent of peel ripeness.     

Symptomology and etiology of a new disease,yellow stunt,and root rot of standing milkvetch caused by <Emphasis Type="Italic">Embellisia</Emphasis> sp. in Northern China

An Embellisia sp. has been established as the cause of a new disease of the herbaceous perennial forage legume, ‹standing milkvetch’ (Astragalus adsurgens Pall.) in Northern China, which severely reduces plant density and degrades A. adsurgens stands. The disease was common at an experimental location in Gansu Province where it was recognized by the occurrence of stunted plants with reddish-brown stems and yellow and necrotic leaf blades. An Embellisia sp. was isolated from symptomatic stem, leaf blade, petiole, and root tissues at varying frequencies of up to 90%. Single-spore isolates grew very slowly on PCA, PDA, V-8 and, wheat hay decoction agar. Pathogenicity was confirmed by inoculation of seeds, dipping 2-day-old pre-germinated seedlings in inoculum and spraying inoculum on 6-month-old plants. Symptoms on test plants included yellow leaf lesions, brown lesions on stems and petioles, stunted side-shoots with yellow, small, distorted and necrotic leaves, shoot blight, bud death, crown rot, root rot, and plant death. The disease is named as ‹yellow stunt and root rot’ of A. adsurgens to distinguish it from diseases caused by other known pathogens. Embellisia sp. is also pathogenic to A. sinicus but not to 11 other tested plant species.     

Safranine fluorescent staining of wood cell walls

Safranine is an azo dye commonly used for plant microscopy, especially as a stain for lignified tissues such as xylem. Safranine fluorescently labels the wood cell wall, producing green/yellow fluorescence in the secondary cell wall and red/orange fluorescence in the middle lamella (ML) region. We examined the fluorescence behavior of safranine under blue light excitation using a variety of wood- and fiber-based samples of known composition to interpret the observed color differentiation of different cell wall types. We also examined the basis for the differences in fluorescence emission using spectral confocal microscopy to examine lignin-rich and cellulose-rich cell walls including reaction wood and decayed wood compared to normal wood. Our results indicate that lignin-rich cell walls, such as the ML of tracheids, the secondary wall of compression wood tracheids, and wood decayed by brown rot, tend to fluoresce red or orange, while cellulose-rich cell walls such as resin canals, wood decayed by white rot, cotton fibers and the G-layer of tension wood fibers, tend to fluoresce green/yellow. This variation in fluorescence emission seems to be due to factors including an emission shift toward red wavelengths combined with dye quenching at shorter wavelengths in regions with high lignin content. Safranine fluorescence provides a useful way to differentiate lignin-rich and cellulose-rich cell walls without counterstaining as required for bright field microscopy.     

Change in susceptibility of satsuma mandarin fruit to sour rot pathogen (Geotrichum candidum citrus race) with relation to biochemical changes during maturation and storage

Change in susceptibility of satsuma mandarin fruit (Citrus unshiu) cultivar “Miyagawawase” to sour rot pathogen was studied with relation to biochemical changes during maturation and storage. The susceptibility of the fruit decreased with the advancement of maturity and was relatively constant during storage at 25°C for 4 wk. The young, green fruit that contained less total soluble solid, sugars and polyphenol, but more citric acid and water contents than mature, yellow fruit was more susceptible to sour rot pathogen. The susceptibility was correlated with total soluble solid, citric acid, sugars and water contents, but not with polyphenol. The results suggested that the difference in susceptibility during maturation was influenced to some extent by several constituents of fruit, although they may not be the only factors involved in susceptibility.     

Assessment of saccharification efficacy in the cellulase system of the brown rot fungus Gloeophyllum trabeum

Brown rot fungi uniquely degrade wood by creating modifications thought to aid in the selective removal of polysaccharides by an incomplete cellulase suite. This naturally successful mechanism offers potential for current bioprocessing applications. To test the efficacy of brown rot cellulases, southern yellow pine wood blocks were first degraded by the brown rot fungus Gloeophyllum trabeum for 0, 2, 4, and 6 weeks. Characterization of the pine constituents revealed brown rot decay patterns, with selective polysaccharide removal as lignin compositions increased. G. trabeum liquid and solid state cellulase extracts, as well as a commercial Trichoderma reesei extract (Celluclast 1.5 L), were used to saccharify this pretreated material, using β-glucosidase amendment to remove limitation of cellobiose-to-glucose conversion. Conditions varied according to source and concentration of cellulase extract and to pH (3.0 vs. 4.8). Hydrolysis yields were maximized using solid state G. trabeum extracts at a pH of 4.8. However, the extent of glucose release was low and was not significantly altered when cellulase loading levels were increased threefold. Furthermore, Celluclast 1.5 L continually outperformed G. trabeum cellulase extracts, although extent of glucose release never exceeded 22.0%. Results suggest methodological advances for utilizing crude G. trabeum cellulases and imply that the suboptimal hydrolysis levels obtained with G. trabeum and Celluclast 1.5 L cellulases, even at high loading levels, may be due to brown rot modifications insufficiently distributed throughout the pretreated material.     

海南火龙果细菌性腐烂病的病原鉴定及田间药剂筛选

细菌性腐烂病是近年在海南火龙果上普遍发生的一种病害。为有效防治该病害,阻止其进一步扩散和蔓延,本研究从临高县东英镇采集病样多份,经病原分离、形态和分子鉴定、致病性测定以及田间药效试验,对其进行了病原鉴定和田间药剂的筛选。结果表明:代表菌株Huo30能产生黄色素,使火龙果致病,与成团泛菌(Pantoea agglomerans)相似性100%,为火龙果细菌性腐烂病的病原菌。4种药剂中,53.8%氢氧化铜WG1000倍液和47%春雷·王酮WP600倍液处理的防效最好,分别为71.05%和69.93%,与另外两个处理的防效差异显著;72%农用链霉素SP5000倍液处理的防效一般,在供试浓度下防效为65.14%;而2%春雷霉素AS600倍液处理对该细菌病害的防效最差,仅为63.31%。本研究结果为海南火龙果的防治提供了重要的理论依据。     

Characterization of blackleg and soft rot from potato in northern Thailand

Blackleg and soft rot of potato cause economic loss through reduced yield and quality. The causal agents of bacterial blackleg and soft rot of potato were identified based on biological data and sequence analyses of the 16S rDNA gene. Between 2016 and 2018, diseased potato stems and tubers were collected in Chai Prakan District, Chiang Mai Province, and Chiang Khum District, Pa Yao Province. The symptoms included black stem lesions, soft rot on tubers, wilting, break down of the stem vascular ring and foliar yellowing. Of 13 bacterial isolates, five were identified as Pectobacterium carotovorum subsp. brasiliense, four‐Dickeya dadantii, two‐Pseudomonas putida and two‐Bacillus altitudinis. Pathogenicity tests of P. carotovorum subsp. brasiliense and D. dadantii resulted in lower leaves turning yellow and wilting followed by blackleg symptoms on lower stems and maceration of tuber tissue. Symptoms caused by P. putida were yellowing and wilting of leaves. B. altitudinis caused yellowing of the lower leaves and wilting followed by drying of leaf tissue. This is a first report of these bacterial pathogens causing blackleg and soft rot of potato in Thailand.     

板栗干腐病研究:Ⅱ.症状及病原

对板栗干腐病症状及病原的研究结果表明:1.板栗干腐病主要发生于种仁上,其病斑大小、质地不一。按色泽可分为褐、黑、白、灰、黄五类。果实其它部位也偶有症状产生;2.此病为多种真菌复合侵染所致。主要的致病菌有Phoma、Phomopsis、Dothiorella、Gloeosporium和Cytospora等属真菌,另有十余种弱寄生及腐生菌有时也混合发生。     

Morphological and molecular characterization of Phytophthora glovera sp. nov. from tobacco in Brazil

A root rot disease of cultivated tobacco called yellow stunt has been observed in the burley tobacco production areas of Brazil since the early 1990s. Root infecting fungi and straminipiles were isolated from the roots of diseased tobacco plants, including a semi-papillate, homothallic, slow growing Phytophthora species. Pathogenicity trials confirmed that Phytophthora sp. caused root rot and stunting of burley and flue-cured tobaccos. Morphological characteristics of the asexual and sexual stages of this organism did not match any reported Phytophthora species and were very different from the widely known tobacco black shank pathogen P. nicotianae. Phylogenetic analysis based on sequences of the internal transcribed spacer rDNA, β-tubulin and translation elongation factor 1-α regions indicated that this organism represents a previously unreported Phytophthora species that is significantly supported in clade 2 and most closely related to P. capsici. However P. glovera differs from P. capsici in a number of morphological characters, most significantly P. glovera is homothallic and produces both paragynous and amphigynous antheridia while P. capsici is heterothallic and produces only amphigynous antheridia. In this paper we confirmed pathogenicity of this species on tobacco and describe the morphological and molecular characteristics of Phytophthora glovera sp. nov.     

Xylogone ganodermophthora sp. nov., an ascomycetous pathogen causing yellow rot on cultivated mushroom Ganoderma lucidum in Korea

Yellow rot, caused by an ascomycetous fungus having a distinctive arthroconidial anamorph, is the most destructive disease of cultivated Ganoderma lucidum in Korea, but the identity of the yellow rot pathogen (YRP) remains uncertain. Isolates have been identified as Xylogone sphaerospora (with putative anamorph Sporendonema purpurascens) or as Arthrographis cuboidea. Therefore we used morphological features, pathogenicity tests and phylogenetic analyses of DNA sequences from the nuclear ribosomal genes, including partial small subunit and internal transcribed spacer regions, and from the gene encoding RNA polymerase second largest subunit to evaluate the relationship between YRP isolates and these species. YRP isolates formed a distinct subgroup within a clade that included X. sphaerospora, A. cuboidea and Scytalidium lignicola, the type species of Scytalidium, but the disposition of the clade within the Leotiomycetes was uncertain. We describe Xylogone ganodermophthora sp. nov. and Scytalidium ganodermophthorum sp. nov. for the teleomorph and anamorph of YRP respectively. Arthrographis cuboidea is reclassified as Scytalidium cuboideum comb. nov., and the anamorph of X. sphaerospora is named Scytalidium sphaerosporum sp. nov. In pathogenicity tests only X. ganodermophthora caused disease in Ganoderma lucidum. Amplified fragment length polymorphism analyses showed that X. ganodermophthora populations from diseased fruiting bodies or from oak wood in Korea consisted of two clonal groups.     

Ditylenchus destructor in Hulls and Seeds of Peanut

The potato rot nematode, Ditylenchus destructor Thorne, is reported for the first time in hulls and seeds of peanut. The populations found differed from D. dipsaei and D. myceliophagus in habitat, number of lateral incisures, shape of tail tip, and length of postvulval sac. Infected hulls had brown necrotic tissue at the point of connection with the peg, and a black discoloration appeared first along the longitudinal veins. Infected seeds were usually shrunken, and testae and embryos had a yellow to brown or black discoloration. Of 877 seed samples graded "damaged" from all major peanut producing areas of South Africa, 73% were infected.     

Seed Rot,a New Disease of Beech Tree Caused by Neonectria ramulariae (anamorph: Cylindrocarpon obtusiusculum)

During a survey of seed diseases of Fagus crenata, a new fungal disease of the seeds was found with high frequency in Akita, northern Japan. Main symptoms are often expressed as browning of the cracked parts from exposed cotyledons and complete loss of viability of infected seeds. Reddish perithecia and whitish yellow sporodochia were occasionally observed symptoms and determined that they were anamorph–telemorph relationship on the basis of both cultural observations. Inoculation studies confirmed that this fungus was the cause of seed rot. The fungus is morphologically identical with Neonectria ramulariae (anamorph: Cylindrocarpon obtusiusculum) that is well known as the soil‐born fungi around the world. Sequences between the authentic isolate of Neo. ramulariae (CBS 151.29) and the pathogenic fungus based on ITS, LSU and tub showed high similarity. Thus, ‘seed rot’, the new disease of beech seeds caused by Neo. ramulariae (anamorph: Cyl. obtusiusculum) was proposed in this study.     

Transformation of 2-hydroxydibenzofuran by laccases of the white rot fungi Trametes versicolor and Pycnoporus cinnabarinus and characterization of oligomerization products

Laccase, a ligninolytic enzyme, was secreted by each ofthe white rot fungi Trametes versicolor and Pycnoporus cinnabarinusduring growth in a nitrogen-rich medium under agitated conditions. Afteraddition of 2-hydroxydibenzofuran to cell-freesupernatants of the cultures, yellow precipitates wereformed. These precipitates were poorly soluble in waterand therefore readily separated from the supernatant. Theproducts formed were more hydrophobic than thesubstrate, as indicated by their longer retention times on areverse phase high-performance liquid chromatographycolumn. Mass spectrometric analysis of the purifiedproducts indicated the formation of oligomers. Analysis ofthe mixture of products by gas chromatography and massspectrometry after derivatization with diazomethanesuggested the formation of at least three dimeric and ninetrimeric products. Carbon-carbon and carbon-oxygenbonds were identified in the dimers and trimers,respectively. The nuclear magnetic resonance spectrum ofthe main dimer suggested coupling of the two monomersat the carbon one position.     

玉米重要自交系的肿囊腐霉茎腐病抗性鉴定与评价

由肿囊腐霉菌(Pythium inflatum Matthews)引起的玉米茎腐病是影响玉米产量的一种重要病害。为进一步拓展可利用的抗源,于2010-2011年在田间采用人工接种方法对287份重要的玉米自交系种质进行了玉米茎腐病的抗性鉴定评价。结果表明,287份鉴定材料中有171份自交系对茎腐病的抗性达到中抗以上水平,占鉴定材料的59.58%,其中高抗自交系共43份,占鉴定材料总数的14.98%;感病类型自交系共116份,占鉴定材料的40.42%,其中高感自交系共95份,占鉴定材料总数的33.10%。Lancaster、Reid及P群种质中具有丰富的茎腐病抗源,而塘四平头种质群中茎腐病抗源相对缺乏,多为感病类型。该研究结果可为今后我国玉米茎腐病抗性种质的引进和改良提供重要参考。     

Comparison of white-rot fungi cultures for decolorization of textile dyestuffs

Four different white rot fungi cultures were used for decolorization of five different textile dyestuffs. Phanerochaeta chrysosporium 671.71, P. chrysosporium MUCL, Coriolus versicolor and C. versicolor MUCL cultures effectively decolorized Everzol Yellow 4GL, Everzol Red RBN, D. Orange K-GL, Everdirect Supra yellow PG and Everzol Turquoise Blue G textile dyestuffs in shake flasks within 9 days of incubation period. Decolorization efficiencies obtained with P. chrysosporium were above 90% for all dyestuffs tested. C. versicolor cultures resulted in varying degree of decolorization efficiencies between 34% and 100%.     

白腐菌对染料脱色和降解作用的研究进展

白腐菌应用于废水处理始于二十世纪八十年代。本文对印染废水的处理方法、白腐菌及其对污染物的降解机理作了简要概述 ,着重介绍了白腐菌对染料脱色和降解作用的研究进展。白腐菌对染料的脱色解降作用机理有部分尚待进一步研究 ;同时 ,白腐菌的吸附作用亦不容忽视。