Varietal Resistance of Flax to Disease

Field experiments, using contaminated seed, have been carried out from 1941 to 1947 to study the reaction of a wide range of both fibre and oil varieties of Linum usitatissimum to attack by Polyspora Lini Laff., Colletotrichum linicola Pethybr. & Laff., Phoma sp. and Melampsora Lini (Ehrenb.) LéV. The tests made with Colletotrichum linicola were supplemented by direct inoculation experiments with young seedlings grown under greenhouse or laboratory conditions.
None of the varieties tested proved to be immune to attack by Polyspora Lini, Colletotrichum linicola or Phoma sp. Herkules, Concurrent, Hindi, La Plata, Saginaw x Ottawa 770 B and Winona x Ottawa 770 B were resistant to the stem-break and browning phases of attack by Polyspora Lini ; Bison, Hindi and La Plata were resistant to attacks by Colletotrichum linicola , while Hindi and La Plata showed some resistance to Phoma sp. Immunity or a 'high' measure of resistance to attack by Melampsora Lini was exhibited by Formosa, Stakhanovets, Textilshchik, U.S.S.R. No. 2 (ex Dugejheshchya), Wada, Argentine Selection (C.I. 112), Baladi, Bolley Golden (C.I. 644), Bombay (C.I. 42), Hindi, Italia Roma (C.I. 1005–2), J.W.S. (C.I. 708–1), Koto (C.I. 872), Kenya (C.I. 709–1), La Plata, Newland (C.I. 188), Ottawa 770B (C.I. 355), Pale Blue Crimped (C.I. 647), Tammes Pale Blue (C.I. 333–1), Williston Golden (C.I. 25–1) and C.I. 836.
All varieties did not show the same reactions to stem-break as to the browning phase of attack by Polyspora Lini and similar differences were noted in the case of the uredospore and teleutospore stages of Melampsora Lini. In certain varieties the stems showed a greater resistance to attack by Polyspora Lini or Melampsora Lini than the leaves.
Seeds of all varieties tested in the field experiments became heavily attacked with Polyspora Lini (except in La Plata), Colletotrichum linicola and Phoma sp.     

STUDIES ON SEED HEALTH

An account is given of the survey made in 1940-55 to determine the incidence of the seed-borne fungal parasites of flax. It was shown that fibre flax seed produced in eastern and south-eastern England was relatively free from contamination with Colletotrichum linicola, Polyspora lini and Phoma sp. and that there was no build-up of infection in seed stocks in these areas. In the wetter and cooler regions west and north of the Pennines, conditions were more favourable for these fungi, and seed contamination tended to increase.
Seed contamination with Botrytis cinerea was general throughout the United Kingdom, with a tendency to be higher in coastal and upland areas. The incidence of Fusarium lini and Alternaria linicola in fibre flax seed produced in the United Kingdom was negligible.
The examination of seed samples from other countries indicated the possible importance of P. lini in Denmark, of B. cinerea and C. linicola in the Netherlands, of A. linicola as a contaminant of oil flax seed in Sweden, and of C. linicola in parts of Canada.
Seed disinfection, using a thiram product, proved useful for the control of flax diseases in general, but should be used as an ancillary to the method of avoiding seed infection by limiting the production of seed flax to areas where the risk of contamination is slight or absent. Where there is any risk of a build-up of contamination, seed disinfection should be carried out as a routine practice each season.     

The relation between the contamination of flax seed with Polyspora Lini Laff. and Colletotrichum linicola Pethybr. & Laff. and the incidence of disease in the crop

Using naturally contaminated seed it is shown that the incidence of the seedling, stem-break and browning phases of attack by Polyspora Lini Laff. in flax crops is related to the contamination of the seed with the parasite, the relationship being closer at low or moderate than at high levels of seed contamination. Heavy attacks of the disease did not occur when the number of contaminated seeds was less than 5%. A similar relationship was found to exist between the contamination of seed with Colletotrichum linicola Pethybr. & Laff. and the incidence of seedling blight in the crops.     

Observations on the effects of browning (Polyspora Lini Laff.) of flax on seed production

An account is given of observations made on the effects on seed production of the incidence of the browning phase of the disease of flax caused by Polyspora Lini Laff. The work was carried out during three seasons.
Disinfection of seeds before sowing exercises an effect on the average weight of the well-developed seeds harvested, and the results obtained show that the intensity of the attack of browning in crops is inversely correlated with the weight of 1000 well-developed seeds. When poorly developed seeds are separated from the remainder at harvest, evidence obtained in one year suggests that the percentage number of such seeds may be directly related to the incidence of browning in the crop. It was found in each of two years that more of the poorly-developed than of the well-developed seeds were contaminated with P. Lini. Evidence available for one year suggests that the viability of well-developed seeds is not related to the incidence of browning.     

The prevention of seed-borne diseases of flax by seed disinfection II. Comparison of the dusting, short wet and fixation methods of treatment

Suitable organo-mercury preparations applied by the short wet method of seed treatment and organo-mercury powders, of the type used for treating cereal seeds, fixed to the seed with water by the fixation method of treatment, gave as satisfactory control of seedling blight and better control of stem break and browning than a proprietary dry fungicide containing tetra-methyl thiuram disulphide (Nomersan) applied at the rate of 12 oz./cwt. of seed.
Treatment of seed heavily infected with Polyspora Lint using an efficient fungicide resulted in highly significant increases in crop and fibre yields, while in the case of seed heavily infected with Colletotrichum Lini similar treatments significantly increased the yield of fibre but not the crop yield. Some treatments significantly increased the crop and fibre yields even when the seed used was only slightly contaminated with P. Lini and C. Lini. The results presented support the suggestion that effective treatment of the seed may produce an increase of fibre not directly attributable to the prevention of seedling blight or stem break and browning but which may be explained by a general beneficial effect due to seed disinfection.
The results obtained suggest that no treatment consistently affected crop establishment in the field.     

板栗干腐病研究:Ⅰ.树体及果实中真菌区系分析

详细地调查了我国不同产栗区及栗不同生长期中,树体及栗果实的自然带菌情况,分析了板栗各生长期真菌区系的变化及其与栗干腐病发病的关系。结果初步证明,栗树整个生长期中都带菌,只是不同生长期和部位所带微生物的数量和种类有所不同。例如,栗树枝条、芽、栗棚和成熟栗子的带菌情况不是不同的,也即在不同生长期和不同部位,微生物的区系组成有较大差异。其中分离频率较高的真菌有Phoma sp.、Dothiorella sp.、Sphaeropsis sp.、Gloeosporium sp.、Cytospora sp.、Alternaria sp.、Rhizoctonia sp.、Comeothyrium sp.、Phomopsis sp.、Fusarium sp.等。真菌种类最多的时期是花期和栗实贮藏期。调查结果还表明,不同地区真菌区系组成有较大的差异,其中致病和弱致病菌所占比例高低顺序为:西南>长江流域>淮河流域>燕山地区。分布较广的致病菌有Phoma sp.、Dothiorella sp.、Gloeosporium sp.、Rhizoctonia sp.、Alternaria sp.等。从分析栗树微生物区系变化与干腐病发病的关系中看出,某一地区干腐病的轻重,与该地区的常见致病菌的分布与数量比例有关。致病菌数量及种类多,则干腐病重,反之,则轻。     

Inhibition of Some Rot Fungi Polygalacturonases by Allium cepa L. and Allium porrum L. Extracts

Extracts of Allium cepa and A. porrum - contain factors that inhibit to various extents polygalacturonases (PGs) produced in vitro by Sclerotinia sclerotiorum, Botrytis cinerea, Fusarium moniliforme, Phoma terrestris, Sclerotium cepivorum, Macrophomina phaseolina, Didymella bryoniae and Phoma lycopersici. The PG inhibition rank changed using leek or onion extract. The inhibition factors are possibly proteins, do not present particular specificity and act against PGs of fungi pathogens and non pathogens for these plant species.     

THE GROWTH OF BOTRYTIS CINEREA PERS., FUSARIUM CAERULEUM (LIB.) SACC., AND PHOMA FOVEATA FOISTER IN THE PRESENCE OF TETRACHLORONITROBENZENE ISOMERS

The linear growth of Botrytis cinerea, Fusarium caeruleum and Phoma foveata in culture was reduced in the presence of vapour from any of the three isomers of tetrachloronitrobenzene. The isomers were fungistatic but not fungicidal.
Differences in activity were observed amongst the isomers. The 2:3:4:6 isomer was the most active against all three test fungi. 2:3:5:6-TCNB (tecnazene) was more active than 2:3:4:5-TCNB against Botrytis cinerea , but less active against Fusarium caeruleum and Phoma foveata . Two strains of Fusarium caeruleum resistant to the 2:3:5:6 isomer were not resistant to the other two isomers, although they were more resistant than their 2:3:5:6-TCNB sensitive parent strains.
Sporulation and sclerotial production by Botrytis cinerea were completely suppressed by 2:3:5:6-TCNB and 2:3:4:6-TCNB but not by the 2:3:4:5: isomer.     

Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 show increased susceptibility to a group of fungal and oomycete pathogens

The behaviour of Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 was investigated in response to fungal and oomycete infections. The importance of NpPDR1 in plant defence was demonstrated for two organs in which NpPDR1 is constitutively expressed: the roots and the petal epidermis. The roots of the plantlets of two lines silenced for NpPDR1 expression were clearly more sensitive than those of controls to the fungal pathogens Botrytis cinerea , Fusarium oxysporum sp., F. oxysporum f. sp. nicotianae , F. oxysporum f. sp. melonis and Rhizoctonia solani , as well as to the oomycete pathogen Phytophthora nicotianae race 0. The Ph gene-linked resistance of N. plumbaginifolia to P. nicotianae race 0 was totally ineffective in NpPDR1 -silenced lines. In addition, the petals of the NpPDR1 -silenced lines were spotted 15%–20% more rapidly by B. cinerea than were the controls. The rapid induction (after 2–4 days) of NpPDR1 expression in N. plumbaginifolia and N. tabacum mature leaves in response to pathogen presence was demonstrated for the first time with fungi and one oomycete: R. solani , F. oxysporum and P. nicotianae . With B. cinerea , such rapid expression was not observed in healthy mature leaves. NpPDR1 expression was not observed during latent infections of B. cinerea in N. plumbaginifolia and N. tabacum , but was induced when conditions facilitated B. cinerea development in leaves, such as leaf ageing or an initial root infection. This work demonstrates the increased sensitivity of NpPDR1 -silenced N. plumbaginifolia plants to all of the fungal and oomycete pathogens investigated.     

Are fungi important for breaking seed dormancy in desert species? Experimental evidence in Opuntia streptacantha (Cactaceae)

Seeds of Opuntia spp. have physiological dormancy; they need a period of after-ripening to break dormancy, and the embryos have low growth potential. We evaluated the combined effects of seed age and presence of fungi on the testa on germination of Opuntia streptacantha, an abundant species in the Chihuahuan Desert (Mexico), assuming that older seeds have broken seed dormancy and fungi can reduce mechanical resistance to germination. In a preliminary experiment, we found no germination of 9-year-old (1998) and freshly collected (2007) seeds. However, we obtained 67% and 27% germination from 9-year-old and fresh non-sterilized seeds, respectively, and found fungi growing on the testa of all germinated seeds. Two fungal strains were isolated and identified using ribosomal internal transcribed spacer (ITS) sequence analysis: Penicillium chrysogenum and Phoma sp. In a second experiment, we inoculated seeds with strains of P. chrysogenum and Phoma sp., as well as Trichoderma koningii and binucleate Rhizoctonia (Gto17S2), to evaluate their ability to break seed dormancy. Seeds inoculated with P. chrysogenum, Phoma sp. and T. koningii had higher germination than controls for both seed ages, but germination was higher in older seeds. Scanning electron microscopy showed that these fungi eroded the funiculus, reducing its resistance. Binucleate Rhizoctonia did not lead to germination and controls had almost no germination. Our results strongly indicate that fungi are involved in breaking seed dormancy of O. streptacantha, and that the effect of fungi on seeds is species-specific.     

<i>In vitro</i> evaluation of antifungal activity of Agave (<i>Agave scabra</i>, Salm Dyck) extracts against post-harvest mushrooms

The agricultural sector, and particularly the horticultural production, has a singular importance in agriculture, considering that it ranks second on agricultural products, nationally and worldwide. Fungal diseases are one of the major causes of vegetable loss during storage, reducing their nutritional value, quality and sale price. Vegetables are usually exposed to diverse treatments with chemical products before storage; as a result, fungal populations develop an increased resistance over time becoming more difficult to control. Because of this, research efforts toward finding more suitable chemicals to control fungal diseases are needed. Natural extracts may be an alternative solve this problem. In the present investigation the fungicidal activity of aqueous and ethanol extracts of Agave scabra was evaluated on the growth of Botrytis cinerea, Mucor sp., Aspergillus niger, Fusarium sp. and Penicillium sp., whose strains were isolated from potato and tomato. To assess their effects, the agar-dilution and agar-well techniques were performed. The ethanol extract was more effective against Botrytis cinerea and Mucor sp. when the agar-well method was used. However, when using the agar-dilution method the ethanol extract of Agave scabra inhibited the growth of Botrytis cinerea, Mucor sp. and Penicillium sp.     

The control of postharvest decay in table grapes using acetaldehyde vapours

Grapes ( Vitis vinifera L. cv. 'Sultanina') harvested at the end of the 1985–1988 seasons, received postharvest application of acetaldehyde (AA) vapours for 24–40 h. Treatment with AA vapour at 20 °C or 0 °C reduced significantly the decay caused by several fungi: Botrytis cinerea, Rhizopus stolonifer, Aspergillus niger and Alternaria alternata . In grapes treated with 0.5% AA for 24 h, no R. stolonifer was found after 8 days of storage at 20 °C. Treatment with 0.25% AA vapour for 40 h of grapes cv. 'Perlette' inoculated with R. stolonifer reduced the decay by 89%.     

番茄灰霉病生防链霉菌筛选及鉴定

【背景】由灰葡萄孢侵染所致的番茄灰霉病是一类重要的真菌病害,生物防治具有环境友好、病原菌不易产生抗药性等特点,是果蔬灰霉病绿色防控的有效措施。【目的】筛选对番茄灰霉病具有防病作用且能促进番茄种子发芽的广谱拮抗性链霉菌,并明确该菌株种级分类地位。【方法】采用琼脂块法筛选拮抗番茄灰霉病菌的链霉菌菌株,采用对峙培养法和生长速率法检测菌株T22抑菌谱,通过产胞外酶活性检测、离体叶片防效和种子发芽试验明确该菌株的防病促生相关特性,根据形态学特征、生理生化特性和分子生物学方法对该菌株进行种类鉴定。【结果】从分离的56株放线菌中筛选到14株对番茄灰霉病菌具有拮抗效果的放线菌菌株,其中链霉菌T22对番茄灰霉病菌抑制作用最强,且具有较广抑菌谱,同时菌株T22具有产生纤维素酶和几丁质酶的能力。菌株T22无菌发酵滤液对番茄灰霉病菌、桃褐腐病菌、黄瓜枯萎病菌抑菌率分别为84.6%、81.5%和79.1%;其无菌发酵滤液原液对番茄灰霉病离体防效为55.1%;100倍稀释液处理番茄种子,胚轴、胚根和种子活力指数分别增加15.1%、29.7%和43.9%。根据形态学特征、生理生化特性和多基因聚类分析将链霉菌T22鉴定为白黑链霉菌(Streptomycesalboniger)。【结论】白黑链霉菌T22具有较强的抗真菌、产胞外酶、防病和促生活性,在番茄灰霉病生物防治中具有较好的开发应用潜力。     

Microbial contamination of cell cultures: a 2 years study.

Cell line contamination is a major drawback of main cell banks of the world and it has cost of losing important biological products or valuable research. The causative agents are different chemicals, invertebrates, bacteria, fungi, parasites, viral species and even other cell lines. In this retrospective study, cell lines from various species such as human, fish, insect, animals either offered or accessed through usual official accession in CGBRI were studied during 2 years (2002-2004) to detect their microbial contaminations and the causative organisms. Samples were taken for sterility test upon cell lines receipt and upon each cell line sub-culture. Samples were examined for bacterial (including mycoplasmas) and fungal contamination using conventional microbiological techniques. The study excluded parasites, viruses and other contaminating agents. This study revealed 39% of specimens were contaminated. The major contaminating agents were mycoplasmas (19%) followed by mixed infection (8%), fungi (8%) and bacteria (4%). Among various bacterial species (except mycoplasmas) Bacillus sp., Enterococcus sp. and Staphylococcus sp. are main bacterial agents and among various fungi Aspergillus sp. followed by Penicillium sp., Sepedonium sp. and Botrytis sp. were main fungal causative agents of CGBRI cell line contamination. Our study also delineates each cell line contamination rate and its causative agents. This is the first report of cell culture contamination from cell banks of Middle-East countries like Iran.     

A world-wide survey of the microflora of Dactylis glomerata seed*

The fungal microflora of orchard (cock's-foot) grass seed (Dactylis glomerata L.) was determined for 140 samples obtained from thirteen countries. The microflora was assessed by visual examination of dry seed (20–50 x), by microscopic examination of centrifuged seed washings and by incubating seed on 2 % malt extract agar (MA) under a 10-day regime of diurnal cycling of temperature (23-9^oC/i8-3^oC) and near-ultraviolet radiation (12 h NUV/ 12 h dark). More than twenty-five species of potentially pathogenic fungi and forty species of saprophytes were detected. The pathogens included an Ascochyta sp., Botrytis cinerea, nine species of Drechslera including D. dactylitis (infested 23% of seed lots) and D. Useptatum (10% of seed lots), five species oiFusarium including F. avenaceum (5 % of seed lots), Lep-tosphaeria sp., Phleospora sp., Phoma sp., Phomopsis sp., Pyrenochaeta sp., Rhizoctonia sp., Rhynchophoma sp., Septoria sp. and Stagonospora sp. Many more fungi were identified from seed plated on MA and exposed to NUV than by examination of seed washings or visual examination of dry seed. Several of the fungi that were detected are known to produce mycotoxins.     

Production of polysaccharide-degrading enzymes by saprophytic fungi from glyphosate-treated flax and their involvement in retting

The fungi present on glyphosate-treated flax plants were isolated. Cladosporium herbarum, Epicoccum nigrum, Botrytis cinerea and yeasts occurred most frequently immediately after glyphosate treatment but as retting progressed the frequency of occurrence of Fusarium culmorum, Alternaria alternata and a Phoma sp. increased. Many of the fungi isolated from retting flax were also present as epiphytes on healthy flax stems. Glyphosate was shown to be fungitoxic in vitro but it had only a very slight effect on fungi colonising the flax. The application of sucrose and urea to flax 1 wk after glyphosate treatment resulted in more rapid fungal colonisation of the stems, but did not significantly enhance retting. When grown on sterilised flax stem sections, fungi known to be saprophytic on flax produced polysaccharide-degrading enzymes. All seven fungi tested produced polygalacturonase, pectin-lyase and xylanase. The greatest cellulase activity was present in stem tissues inoculated with F. culmorum and the Phoma sp. while no cellulase was detected in tissue inoculated with B. cinerea, a Mucor sp. or a Penicillium sp. Extracts from flax inoculated with the cellulolytic fungi caused the solubilisation of native cellulose. Pectinases, xylanase and cellulase were also detected in naturally-colonised senescing and dead flax stems. Stems which had been treated with a sucrose solution tended to contain the greatest enzyme activity.     

Filamentous Fungi Isolated from Estuarine Sediments Contaminated with Industrial Discharges

Filamentous fungi were isolated from estuarine sediments collected from two contaminated sites. One site was contaminated mainly by polycyclic aromatic hydrocarbon (PAH) with a concentration around 407?µg g^?1 of different PAHs, and the other by different sources of industrial pollutants; both were compared to a pristine site. All three sites were located in the Baixada Santista, São Paulo State, Brazil. The aim of the present investigation was the isolation of filamentous fungi from pristine and industrially polluted sediments in order to assess the mycobiota present in those sites and to evaluate their tolerance to phenanthrene and pyrene. Most of the isolated fungi were mitosporic ascomycetes, including Aspergillus sp., Chrysosporium sp., Cyclothyrium spp., Gliocladium sp., Penicillium spp., Phoma spp., and Trichoderma spp. There were also representatives of sexual Ascomycetes, Basidiomycetes, and Zygomycetes. The results showed that 59% of the evaluated fungi were tolerant to pyrene and 30% to phenanthrene. Representatives of Trichoderma were the most tolerant among the filamentous fungi investigated. A representative of Penicillium simplicissimum was the only isolate tested that had a better growth in the presence of pyrene than in its absence.     

Epicoccum nigrum for biocontrol agents in vitro of plant fungal pathogens

Epicoccum nigrum strains were evaluated in vitro as potential biological agents for control of the growth of Fusarium avenaceum, F. graminearum, F. oxysporum and Botrytis cinerea. Individual biotic effects of five strains of E. nigrum on the various fungi were determined using the biotic series method elaborated for fungi, on potato dextrose agar (PDA - Difco) medium. Our results show that E. nigrum strains limited the growth of all isolates of Fusarium spp., but not of those of Botrytis cinerea.     

枯草杆菌BS-98分泌的抗真菌蛋白的分离纯化及其部分性质的研究

拮抗菌（Bacillussubtilis）BS-98菌株在BPY液体培养基中产生的蛋白质经硫酸铵分级盐析、SephsdexG-100柱层析、DEAE-纤维素柱层析和SephadexG－100柱再层析后,分离纯化得到的抗菌蛋白在电泳中显现出三条带。经初步纯化的抗菌蛋白对热稳定,对蛋白酶部分敏感。抑菌谱测定表明,抗菌蛋白对芦笋茎枯病菌、小麦赤霉病菌、棉花枯萎病菌、棉花黄萎病菌、灰霉菌、立枯丝核菌等病原真菌及黄瓜角斑病菌都具有强烈的抑制作用。     

Use of GUS Transformants of Trichoderma harzianum Isolate T39 (TRICHODEX) for Studying Interactions on Leaf Surfaces

Trichoderma harzianum , isolate T39 (TRICHODEX), was transformed with the GUS ( βglucuronidase) reporter gene to visualize the interaction with Botrytis cinerea and to determine potential mechanisms involved in biocontrol. T39GUS transformants did not appear to penetrate the bean leaf epidermis nor grow into the mesophyll via stomata. No direct penetration or coiling was observed between hyphae and conidia of the T39GUS transformants and of B. cinerea , however, structures of the pathogen were stained blue. Similarly, blue substrate accumulated in various non-transformed fungi such as Alternaria sp., Colletotricum acutatum and the wild-type isolate T39 when co-inoculated on leaves and plates with the T39GUStransgenic strains of T. harzianum and Fusarium oxysporum f. sp. niveum . Therefore, the role of diffusible compounds, specifically from T. harzianum transformants, will need further investigation.