Colony Margin Research Articles

First Report of Phytophthora ramorum Causing a Leafspot on Loropetalum chinense, Chinese Fringe Flower in California.

Chinese fringe flower is a popular landscape plant in California for its red evergreen foliage and its showy red flowers in the spring. In April 2007, a sample was submitted to the California Department of Food and Agriculture diagnostic laboratory from Sacramento County as part of an inspection of a nursery for Phytophthora ramorum. A sample was taken from Loropetalum chinense because the inspector noticed very small spots and defoliation in the crop, even though P. ramorum was not detected in previous samples sent to the lab with similar symptoms. Six 5-mm2 pieces of the leaves were placed on CMA-PARP (1) medium as part of our standard nursery screening, even though no lesions were seen. An organism with coralloid coenocytic hyphae, chlamydospores, and ellipsoidal semi-papillate sporangia matching the description of P. ramorum (2) grew into a snowflake-shaped colony from two pieces. On closer inspection of the leaves, small green lesions of approximately 3 to 5 mm wide were visible, especially when the leaves were backlit. For sporangial production, a 6-mm plug was transferred from the colony margin of the isolate onto V8 juice agar (V8). Sporangia, produced on V8 plugs incubated in dH20 for 2 days, were from 41 to 61 × 23 to 32 μm (48.7 × 29.3 μm average) with a length to breadth ratio from 1.3 to 2.0 (average 1.7). Chlamydospores on CMA-PARP were 36.7 to 60.1 μm (49.1 μm diameter average). From 2008 to 2011, similar symptoms were found on L. chinense from Contra Costa, San Joaquin, and Los Angeles Counties. The same organism was isolated from these infected plants. To confirm pathogenicity on L. chinense, five nursery-grown plants in 3.78-L pots were inoculated with three isolates each. Plants were inoculated with 6-mm plugs taken from the margin of a 7- to 10-day old culture grown on V8. Plant leaves were wounded with a sterile pushpin and two colonized plugs were covered with a freezer tube cap filled with sterile dH2O and attached to the underside of the leaves with a sterile pin-curl clip (4). Inoculated plants were sprayed with water, covered with plastic bags, and incubated for 2 days, when bags and plugs were removed. Four leaves per isolate were inoculated on each plant and four leaves per plant were treated similarly with uncolonized V8 plugs as a control. Plants were incubated for 12 to 14 days at 18°C (16-h photoperiod) when lesions were visible and some of the leaves began to abscise. P. ramorum grew from each lesion produced on inoculated leaves and no Phytophthora spp. grew from the control leaves when isolated onto CMA-PARP. Inoculations were repeated with similar results. The internal transcribed spacer region (ITS) of rDNA was amplified and sequenced from the isolates using ITS1 and ITS4 primers as described by White et al. (3). BLAST analysis of the sequenced amplicons (GenBank JQ361743 through JQ361745) showed 100% identity with the ITS sequence of P. ramorum (GenBank AY594198). P. ramorum is a quarantine pathogen with many hosts (2,4). Leaf spots on L. chinense caused by P. ramorum are inconspicuous and missing this disease during nursery inspections could lead to unintended spread to neighboring host plants.

A quest for indigenous truffle helper prokaryotes

Tuber aestivum is the most common European truffle with significant commercial exploitation. Its production originates from natural habitats and from artificially inoculated host tree plantations. Formation of Tuber ectomycorrhizae in host seedling roots is often inefficient. One possible reason is the lack of indigenous associative microbes. Here we aimed at metagenetic characterization and cultivation of indigenous prokaryotes associated with T. aestivum in a field transect cutting through the fungus colony margin. Several operational taxonomic units (OTUs) showed close association with the T. aestivum in the ectomycorrhizae and in the soil, but there was no overlap between the associative prokaryotes in the two different habitats. Among those positively associated with the ectomycorrhizae, we identified several bacterial genera belonging to Pseudonocardineae. Extensive isolation efforts yielded many cultures of ectomycorrhizae-associative bacteria belonging to Rhizobiales and Streptomycineae, but none belonging to the Pseudonocardineae. The specific unculturable Tuber-associated prokaryotes are likely to play important roles in the biology of these ectomycorrhizal fungi, including modulation of competition with other symbiotic and saprotrophic microbes, facilitation of root penetration and/or accessing mineral nutrients in the soil. However, the ultimate proof of this hypothesis will require isolation of the microbes for metabolic studies, using novel cultivation approaches.

Development of a novel two-dimensional directed differentiation system for generation of cardiomyocytes from human pluripotent stem cells

BackgroundHuman pluripotent stem cells (hPSCs) hold great promise for treating ischemic heart disease. However, current protocols for differentiating hPSCs either result in low yields or require expensive cytokines. MethodsHere we developed a novel two dimensional (2D) stepwise differentiation system that generates a high yield of cardiomyocytes (CMs) from hPSCs without using special cytokines. Initially, undifferentiated hPSCs were transferred onto Matrigel-coated plates without forming embryoid bodies (EBs) for a few days and were cultured in bFGF-depleted human embryonic stem cells (hESCs) medium. When linear cell aggregation appeared in the margins of the hPSC colonies, the medium was changed to DMEM supplemented with 10% fetal bovine serum (FBS). Thereafter when cell clusters became visible, the medium was changed to DMEM with 20% FBS. Results and conclusionsAt about two weeks of culture, contracting clusters began to appear and the number of contracting clusters continuously increased, reaching approximately 70% of all clusters. These clusters were dissociated by two-step enzyme treatment to monolayered CMs, of which ~90% showed CM phenotypes confirmed by an α‐myosin heavy chain reporter system. Electrophysiologic studies demonstrated that the hPSC-derived CMs showed three major CM action potential types with 61 to 78% having a ventricular-CM phenotype. This differentiation system showed a clear spatiotemporal role of the surrounding endodermal cells for differentiation of mesodermal cell clusters into CMs. In conclusion, this system provides a novel platform to generate CMs from hPSCs at high yield without using cytokines and to study the development of hPSCs into CMs.

First Report of Sclerotinia Stem Rot Caused by Sclerotinia sclerotiorum on Brassica carinata in Florida.

Brassica carinata A. Braun, commonly referred to as Ethiopian rapeseed, a near relative of collards and mustard, has become the object of increasing interest as an oil crop. It has been reported that B. carinata adapts better and is more productive than B. napus (canola) in adverse conditions, such as clay and sandy soils and under low management cropping systems (1). In late February 2012, symptoms typical of sclerotinia stem rot were observed in B. carinata trials (cultivars 090867 EM and 080814 EM) at the University of Florida, North Florida Research and Education Center located in Quincy, FL. Approximately 20 to 30% of the B. carinata cultivar 090867 EM were observed to have symptoms and approximately 5% of cultivar 080814 EM displayed symptoms. Stems had white mycelia growing on the outside, plants were lodging and spherical to cylindrical, 3 to 8 mm, and black sclerotia were found outside and inside bleached stems. Sclerotia from diseased stems were surface sterilized and placed in 9-cm diameter petri plates on quarter strength potato dextrose agar (PDA) amended with 25% lactic acid. Fungal cultures consisting of white mycelia and medium-sized (mean 4 mm), black, irregular sclerotia were consistently recovered and identified as Sclerotinia sclerotiorum (Lib.) de Bary based on morphological characteristics (3). Sequence analyses were conducted on mycelium by extracting fungal DNA with the Qiagen DNeasy Plant Mini Kit (Valencia, CA). PCR amplification was performed using primers ITS1 and ITS4. The BLAST search revealed that the sequence (GenBank Accession No. JX307092) had 99 and 100% sequence identity with S. sclerotiorum GenBank accessions JN013184.1 and JN012606.1. Pathogenicity was determined by inoculating six 1-month-old B. carinata plants (cultivars 090867 EM and 080814 EM) that were grown in greenhouse pots (20 cm in diameter). Mycelia plugs (8 mm in diameter) were excised from the colony margin after 6 days of incubation at room temperature (approximately 25°C), and placed on stems, at the soil line, of B. carinata plants. Six control plants were inoculated with noncolonized PDA plugs. All plants were enclosed in plastic bags that had been sprayed with water on the inside to maintain high humidity and kept in the laboratory at room temperature (approximately 25°C). Symptoms similar to those observed in the field were evident after 3 days on inoculated plants and S. sclerotiorum was reisolated. In the controls, no symptoms developed and the fungus could not be isolated. The experiment was repeated with similar results. The majority of rapeseed production is in North Dakota, where sclerotinia stem rot caused by S. sclerotiorum is a major fungal disease affecting production (2). Currently, there is no significant B. carinata production in Florida; however, interest in biofuels could lead to an increase in planted acreage and sclerotinia stem rot could become a significant disease problem in areas of Florida were B. carinata is planted. To our knowledge, this is the first report of sclerotinia stem rot of B. carinata caused by S. sclerotiorum in Florida.

The archaeology of not being governed: A counterpoint to a history of settlement of two colonies in the eastern Caribbean

In this article we examine the role of informal settlements inhabited by Europeans, Africans and, potentially, indigenous people in the eighteenth-century insular Caribbean. Rather than simply being frontier settlements established in anticipation of formal colonization, in many cases settlements on and beyond the margins of colonies represent alternative possibilities and facilitate ways of life, modes of production, and means of trade and exchange that are at odds with expected norms of colonial society. We view such settlements as holdouts, practicing what James Scott refers to as the ‘art of not being governed’. To make this argument we compare ethnohistorical data related to settlement patterns in St John and Dominica and archaeological data retrieved from household excavations of plantation settlements dating to the eighteenth century. Examining such settlements allows us to map the range of variation in colonial life during the apogee of plantation-based slavery.

Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments

Homologs of the green fluorescent protein (GFP) are a prevalent group of host pigments responsible for the green, red and purple-blue colours of many reef-building corals. They have been suggested to contribute to the striking coloration changes of different corals species in response to wounding and infestation with epibionts/parasites. In order to elucidate the physiological processes underlying the potentially disease-related colour changes, we have analysed spatial and temporal expression patterns of GFP-like proteins and other biomarkers in corals from the Red Sea, the Arabian/Persian Gulf and Fiji both in their natural habitat and under specific laboratory conditions. The expression of distinct GFP-like proteins and the growth marker proliferating cell nuclear antigen was upregulated in growing branch tips and margins of healthy coral colonies as well as in disturbed colony parts. Furthermore, phenoloxidase activity increased in these proliferating tissues. It is thus demonstrated that locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals and, moreover, these processes can be detected utilizing the excellent biomarker properties of GFP-like proteins. Finally, the results of this work suggest an additional vulnerability of corals in predicted future scenarios of increased ocean acidification, warming and eutrophication that are anticipated to reduce coral growth capacity.

First Report of Brown Rot Caused by Monilinia fructicola on Stored Apple in Serbia.

Monilinia fructicola (G. Winter) Honey is a causal agent of brown rot of stone fruits, occasionally affecting pome fruits as well. The pathogen is commonly present in North and South America, Oceania, and Asia, but listed as a quarantine organism in Europe (4). After its first discovery in France in 2001, its occurrence has been reported in Germany, Hungary, Italy, Poland, Romania, Slovenia, Spain, Switzerland, Austria, and the Slovak Republic (1). In February 2011, during a survey for fungal postharvest pathogens in cold storage conditions, apple fruits (Malus domestica Borkh.) grown and stored in the Grocka Region, Serbia, were collected. All pathogens from symptomatic fruits were isolated on potato dextrose agar (PDA). One isolate from apple fruit cv. Golden Delicious with brown rot symptoms was identified as M. fructicola based on morphological and molecular characters. Colonies cultivated on PDA at 22°C in darkness were colorless, but later became grayish, developing mass of spores in concentric rings. Colony margins were even. Conidia were one-celled, limoniform, hyaline, measured 12.19 to 17.37 (mean 13.8) × 8.62 to 11.43 μm (mean 9.9), and were produced in branched monilioid chains (3). Morphological identification was confirmed by PCR (2) using genomic DNA extracted from the mycelium of pure culture, and an amplified product of 535 bp, specific for the species M. fructicola, was obtained. Sequence of the ribosomal (internal transcribed spacer) ITS1-5.8S-ITS2 region was obtained using primers ITS1 and ITS4 and deposited in GenBank (Accession No. JN176564). Control fruits were inoculated with sterile PDA plugs. After 3 days of incubation in plastic containers with high humidity at room temperature, typical symptoms of brown rot developed on inoculated fruits, while control fruits remained symptomless. The isolate recovered from symptomatic fruits showed the same morphological and molecular features of the original isolate. To our knowledge, this is the first report of M. fructicola in Serbia. Further studies are necessary for estimation of economic importance and geographic distribution of this quarantine organism in Serbia.

First Report of Amphobotrys ricini Causing Gray Mold Disease on Acalypha australis in Central China.

In 2008, we isolated a strain of an Amphobotrys sp., CotAr-12, from a cotton plant showing Verticillium wilt symptoms in Hubei Province, China. In October 2010 and 2011, surveys for Amphobotrys sp. on cotton were conducted in 14 counties in Hubei. No signs of an Amphobotrys sp. was observed on cotton. However, a gray mold disease was found on the weed, Acalypha australis in 40 of 51 cotton fields with an average disease incidence of 18.6%. The disease started on the inflorescences at the top of stems or branches and then spread downward to the main stems, branches, and leaves. Abundant sporulation on the necrotic tissues and formation of sclerotia underneath the epidermis or in the stem pith were evident. A total of 128 isolates, including CopAr-5, were obtained from A. australis (1 to 10 isolates per field). All isolates from A. australis and CotAr-12 appeared similar in colony morphology; ragged colony margins, erect conidiophores with long stipes and dichotomous branches at the top, globose and subhyaline conidia with an average diameter of 5.3 to 8.5 μm, and black, oval sclerotia of 0.6 to 26.2 × 0.5 to 19.0 mm. These characteristics matched the description for Amphobotrys ricini (Buchw.) Hennebert (teleomorph Botryotinia ricini [Godfrey] Whetzel) (2). Strains CopAr-5 and CotAr-12 were selected for molecular identification. DNA was extracted from mycelia and used for cloning of three nuclear genes (e.g., G3PDH, HSP60, and RPB2) using the procedures described by Staats et al. (4). The resulting DNA sequences were used for phylogenetic analysis with the corresponding sequences for Botrytis spp. (4). Results showed that strains CopAr-5 (GenBank Accession Nos. JN681883, JN681881, and JN6981879), CotAr-12 (GenBank Accession Nos. JN681882, JN681880, and JN6981878), and Botrytis (teleomorph Botrytinia) ricini (GenBank Accession Nos. GQ860998, GQ860996, and GQ860997) formed a separate clade that was distinct from Botrytis spp., supporting the distinction of Amphobotrys from Botrytis and suggesting that the two strains were Amphobotrys ricini. Pathogenicity was determined by placing mycelia of strains CopAr-5 and CotAr-12 on 10 detached leaves of A. australis, castor bean, and cotton. Control leaves of these plants were inoculated with potato dextrose agar alone. After incubation at 20°C under moist conditions (>90% relative humidity) for 60 h, the control leaves remained healthy, while the leaves of A. australis and castor bean inoculated with both strains formed extensively expanded lesions of 20 and 27 mm in diameter on average, respectively. Both strains also caused disease on cotton leaves with discontinuous and localized lesions of 18 mm in average diameter. A fungus was reisolated from the leaf lesions on these plant species and were identical to Amphobotrys ricini in colony morphology and conidial characteristics. We conclude that Amphobotrys ricini is a major pathogen on A. australis in central China. It is an important pathogen of castor bean (1) and has been reported to infect several euphorbiaceous plants, including A. hispida (3). To our knowledge, this is the first report of Amphobotrys ricini on A. australis.

Effects of Prior Vegetative Growth, Inoculum Density, Light, and Mating on Conidiation of Erysiphe necator

Initiation of asexual sporulation in powdery mildews is preceded by a period of superficial vegetative growth of mildew colonies. We found evidence of a quorum-sensing signal in Erysiphe necator that was promulgated at the colony center and stimulated conidiation throughout the colony. Removal of the colony center after putative signal promulgation had no impact upon timing of sporulation by 48-h-old hyphae at the colony margin. However, removal of the colony center before signaling nearly doubled the latent period. A relationship between inoculum density and latent period was also observed, with latent period decreasing as the number of conidia deposited per square millimeter was increased. The effect was most pronounced at the lowest inoculum densities, with little decrease of the latent period as the density of inoculation increased above 10 spores/mm. Furthermore, light was shown to be necessary to initiate conidiation of sporulation-competent colonies. When plants were inoculated and maintained in a day-and-night cycle for 36 h but subjected to darkness after 36 h, colonies kept in darkness failed to sporulate for several days after plants kept in light had sporulated. Once returned to light, the dark-suppression was immediately reversed, and sporulation commenced within 12 h. Merging of colonies of compatible mating types resulted in near-cessation of sporulation, both in the region of merging and in more distant parts of the colonies. Colonies continued to expand but stopped producing new conidiophores once pairing of compatible mating types had occurred, and extant conidiophores stopped producing new conidia. Therefore, in addition to a quorum-sensing signal to initiate conidiation, there appears to be either signal repression or another signal that causes conidiation to cease once pairing has occurred and the pathogen has initiated the ascigerous stage for overwintering.

温郁金内生真菌Chaetomium globosumL18对植物病原菌的抑菌谱及拮抗机理

PDF HTML阅读 XML下载 导出引用 引用提醒 温郁金内生真菌Chaetomium globosum L18对植物病原菌的抑菌谱及拮抗机理 DOI: 10.5846/stxb201110081465 作者: 作者单位: 吉林农业大学农业部参茸产品质量监督检验测试中心,吉林农业大学附属医院,吉林农业大学农业部参茸产品质量监督检验测试中心,,吉林农业大学农业部参茸产品质量监督检验测试中心,吉林农业大学农业部参茸产品质量监督检验测试中心,吉林农业大学农学院 作者简介: 通讯作者: 中图分类号: 基金项目: 吉林农业大学博士启动基金(201110);浙江省重大科技专项资助项目(2005C13019) Inhibition effects and mechanisms of the endophytic fungus Chaetomium globosum L18 from Curcuma wenyujin Author: Affiliation: ．Jilin Agriculture University，Ginseng and Cartialgenous testing center of Ministry of Agriculture PRC,,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:通过体外培养法,研究了药用植物温郁金内生真菌Chaetomium globosum L18对几种常见的植物病原菌的抑菌谱及其拮抗机理。结果表明,Chaetomium globosum L18对多种植物病原真菌和细菌均有不同程度的抑制作用,具有较广的抑菌谱,但对不同植物病原菌的抑制作用具有显著性差异(P＜0.05),抑制率最高可达到92.9%;抑菌机制结果显示,竞争作用和重寄生作用是其主要的拮抗机制之一;发酵产物抑制作用测定发现, 内生真菌Chaetomium globosum L18能够分泌产生抗菌物质抑制病原菌菌丝的生长和孢子萌发,可引起病原菌菌丝菌丝膨大成串珠状,分枝增多,分枝顶端膨胀后细胞壁破裂,原生质外溢,产生溶菌作用;使分生孢子萌发畸形,萌发率降低。 Abstract:Fungal endophytes are microorganisms that colonize living, internal tissues of plants without causing any immediate, overtly negative effects. Many fungal endophytes produce secondary metabolites and some of these compounds exhibit antifungal and antibacterial activity that strongly inhibits the growth of other microorganisms. Antimicrobial strains are widely distributed among endophytic fungi and do not cause any obvious symptoms on host plants. Infected hosts usually grow quickly, have strong resistance to adverse conditions and diseases, and are immune to herbivory in comparison with uninfected plants. Endophyte-infected plants thus have competitive advantage. Endophytes act as biological control agents by inhibiting pathogen growth by the production of antibiotics, hydrolases, plant growth regulators and alkaloids. They also compete with pathogens for nutrition, enhancing resistance of host plants to diseases and inducing systemic resistance. Endophytic fungi are therefore biological control agents with great potential for applied use. We investigated the antimicrobial properties of an endophytic fungus Chaetomium globosum L18 from a traditional Chinese medicinal plant Curcuma wenyujin Y. H. Chen et C. Ling (Zingiberaceae), on several conventional plant pathogens, using in vitro culturing methods. We thus present a preliminary discussion of the antimicrobial spectrum and antagonistic mechanisms of Chaetomium globosum L18. This fungus had different inhibitory actions on plant pathogenic fungi and bacteria, and wide-ranging inhibitory effects. There was significant difference (P<0.05) on inhibition of different plant pathogenic bacteria; and the inhibition rate was up to 92.9%. Our inhibition experiment showed that competition and mycoparasitism were the main antagonistic mechanisms. When two strains intersected with pathogenic fungi on co-culturing plates, plant pathogens were surrounded, and the margins of colonies gradually collapsed and shriveled. The pathogens stopped growing and began to die; and Chaetomium globosum L18 colonized the nutritious space. Chaetomium globosum L18 parasitized pathogens by parallel intergrowth, intertwining, and even penetrating their mycelia. Our fermented product test showed that Chaetomium globosum L18 was able to strongly inhibit mycelial growth and spore germination. Its presence resulted in mycelia that were twisted and inflated, with increased abnormal branching, broken mycelial walls, and cell contents released. Spores were reduced in number and deformed; germination rate and germination tube length were decreased. 参考文献 相似文献 引证文献

The Ecology of ‘Acroporid White Syndrome', a Coral Disease from the Southern Great Barrier Reef

Outbreaks of coral disease have increased worldwide over the last few decades. Despite this, remarkably little is known about the ecology of disease in the Indo-Pacific Region. Here we report the spatiotemporal dynamics of a coral disease termed ‘Acroporid white syndrome’ observed to affect tabular corals of the genus Acropora on the southern Great Barrier Reef. The syndrome is characterised by rapid tissue loss initiating in the basal margins of colonies, and manifests as a distinct lesion boundary between apparently healthy tissue and exposed white skeleton. Surveys of eight sites around Heron Reef in 2004 revealed a mean prevalence of 8.1±0.9%, affecting the three common species (Acropora cytherea, A. hyacinthus, A. clathrata) and nine other tabular Acropora spp. While all sizes of colonies were affected, white syndrome disproportionately affected larger colonies of tabular Acroporids (>80 cm). The prevalence of white syndrome was strongly related to the abundance of tabular Acroporids within transects, yet the incidence of the syndrome appears unaffected by proximity to other colonies, suggesting that while white syndrome is density dependant, it does not exhibit a strongly aggregated spatial pattern consistent with previous coral disease outbreaks. Acroporid white syndrome was not transmitted by either direct contact in the field or by mucus in aquaria experiments. Monitoring of affected colonies revealed highly variable rates of tissue loss ranging from 0 to 1146 cm−2 week−1, amongst the highest documented for a coral disease. Contrary to previous links between temperature and coral disease, rates of tissue loss in affected colonies increased threefold during the winter months. Given the lack of spatial pattern and non-infectious nature of Acroporid white syndrome, further studies are needed to determine causal factors and longer-term implications of disease outbreaks on the Great Barrier Reef.

Mechanosensitive EPLIN-dependent remodeling of adherens junctions regulates epithelial reshaping

The zonula adherens (ZA), a type of adherens junction (AJ), plays a major role in epithelial cell-cell adhesions. It remains unknown how the ZA is remodeled during epithelial reorganization. Here we found that the ZA was converted to another type of AJ with punctate morphology (pAJ) at the margins of epithelial colonies. The F-actin-stabilizing protein EPLIN (epithelial protein lost in neoplasm), which functions to maintain the ZA via its association with αE-catenin, was lost in the pAJs. Consistently, a fusion of αE-catenin and EPLIN contributed to the formation of ZA but not pAJs. We show that junctional tension was important for retaining EPLIN at AJs, and another force derived from actin fibers laterally attached to the pAJs inhibited EPLIN-AJ association. Vinculin was required for general AJ formation, and it cooperated with EPLIN to maintain the ZA. These findings suggest that epithelial cells remodel their junctional architecture by responding to mechanical forces, and the αE-catenin-bound EPLIN acts as a mechanosensitive regulator for this process.

First Report of Phytophthora Blight Caused by Phytophthora capsici on Snap Bean in New York.

Phytophthora capsici Leonian is an important pathogen of solanaceous and cucurbit crops. Phytophthora blight was first reported on snap bean (Phaseolus vulgaris L.) in Michigan in 2003 (2) and Connecticut in 2010 (3). This report documents the discovery of P. capsici on snap bean (cv. Bronco) grown in Riverhead, NY in September 2008 and August 2010 on snap bean (cv. Valentino) in Holley, NY, more than 690 km away. Disease was favored by frequent rainfall and prolonged wet periods with air temperatures of 24 to 29°C. Both locations were commercial fields previously planted to pepper or cucurbits affected by P. capsici. In Riverhead, infected pods had characteristic yeast-like growth of P. capsici, which were predominantly sporangia. In Holley, large water-soaked lesions were observed on snap bean foliage, and as the disease progressed, leaves became necrotic and detached from the plant. Reddish brown lesions were observed on stems in advance of white areas of sporulation. Infected pods displayed white mycelial growth, were shriveled, and desiccated. P. capsici was isolated from symptomatic tissues. Stems and pods were surface disinfested for 3 min in 0.525% sodium hypochlorite solution, rinsed for 3 min in sterile distilled water, transferred to PARPH (4) media, and incubated at 22°C. After 5 days, hyphae from colony margins were excised and transferred to 15% unclarified V8 agar media. Cultures consisting of white mycelia and ovoid papillate sporangia on long pedicels were identified as P. capsici. Sporangia were 25.0 to 70.0 × 10.0 to 22.5 μm (average 42.0 × 16.25 μm). Identity was further confirmed by PCR primers specific to P. capsici (1). DNA was extracted from mycelia produced on V8 agar and amplification with the species-specific primers resulted in a PCR product of the same size as that obtained from a known isolate of P. capsici. Pathogenicity of the isolate from Holley was determined by two methods on 50-day-old snap bean plants (cv. Valentino) grown in a greenhouse. In method one, four plants were inoculated with 1-cm-diameter mycelial plugs excised from 8-day-old cultures. A single plug was placed against the stem at the soil line. Four control plants were treated similarly with noncolonized agar plugs. In method two, entire plants were atomized with 10 ml of a zoospore suspension (2.6 × 105/ml). Control plants were atomized with sterile distilled water. All plants were placed in a growth chamber with continuous mist for 24 h at 24°C. After 24 h, plants were enclosed in plastic bags and placed in a greenhouse at 27°C. Stem lesions similar to those observed in affected fields were evident on plants treated with mycelia plugs 2 days after inoculation. Plants inoculated with the zoospore suspension developed stem lesions and desiccated pods. Control plants were asymptomatic. P. capsici was successfully recovered from infected plant tissue, fulfilling Koch's postulates. The Riverhead isolate was demonstrated as pathogenic on snap bean and cucumber by placing colonized plugs on pods and fruit that were subsequently incubated in moist chambers (24°C, 90 to 100% relative humidity). P. capsici was successfully recovered from symptomatic pods and fruit. To our knowledge, this is the first report of Phytophthora blight caused by P. capsici on snap bean in New York.

Genetic analysis of growth, morphology and pathogenicity in the F 1 progeny of an interspecific cross between Fusarium circinatum and Fusarium subglutinans

Fusarium circinatum and Fusarium subglutinans are two distinct species in the Gibberella fujikuroi species complex. A genetic linkage map produced from an interspecific cross between these species was used to identify quantitative trait loci (QTLs) associated with variation in mycelial growth and morphology of colony margins (CMs) in the 94 F 1 progeny. Mycelial growth was assessed by measuring culture size at 25 °C and 30 °C, while CM morphology was characterized in the parents and assessed in their F 1 progeny. In order to test the pathogenicity of the progeny, Pinus patula seedlings were inoculated and lesion lengths were measured after 3 weeks. Seven putative QTLs were associated with mycelial growth, three for growth at 25 °C and four at 30 °C. One highly significant QTL ( P < 0.001) was present at both growth temperatures. For CM morphology, a QTL was identified at the same position ( P < 0.001) as the QTL responsible for growth at the two temperatures. The putative QTLs accounted for 45 and 41 % of the total mycelial growth variation at 25 °C and 30 °C, respectively, and for 21 % of the variation in CM morphology. Only one of the 94 F 1 progeny was pathogenic on P. patula seedlings. This observation could be explained by the genetic constitution of this F 1 isolate, namely that ∼96 % of its genome originated from the F. circinatum parent. This F 1 individual also grew significantly faster at 25 °C than the F. circinatum parent ( P < 0.05), as well as more rapidly than the average growth for the remaining 93 F 1 progeny ( P < 0.05). However, no association was found between mycelial growth and pathogenicity at 25 °C. The highly significant QTL associated with growth at two temperatures, suggests that this is a principal genomic region involved in mycelial growth at both temperatures, and that the same region is also responsible for CM morphology.

First Report of Botrytis Leaf Blight and Fruit Rot on Schisandra chinensis Caused by Botrytis cinerea in China.

Schisandra (Schisandra chinensis (Turcz.) Baill) is a perennial plant belonging to Magnoliaceae. It is a very important medicinal herb in China and is mainly used for treatment of insomnia and memory decay. From July to September 2008, an unknown leaf blight and fruit rot on schisandra were first observed at Jingyu County, Jilin Province. The same symptoms were detected in other areas of Jilin Province, such as Ji'an City, Baishan City, and Hunchun City. Initially, some small, brown spots appeared on the tip or margin of the leaves. Light brown or brown necrotic lesions developed and eventually covered entire leaves. Seriously affected leaves were rolled or distorted and eventually became completely dry and brittle. Small spots appeared on the surface of mature fruits, coalesced, and the fruits finally dropped. Gray mycelia and conidiophores developed on the diseased leaves and fruits. To isolate the causal agent, conidia and conidiophores were scraped aseptically from the internal tissues, suspended in sterile water, and streaked onto the surface of potato dextrose agar (PDA). Single-hyphal tips were transferred on PDA and the isolated fungus was identified as Botrytis cinerea Pers.: Fr. on the basis of its morphological characteristics and internal transcribed spacer (ITS) sequence. Colonies of B. cinerea on PDA were colorless at first and became gray to brown 20 days later with the mycelium growth and conidia producing in cultures. Conidia are single celled, lemon shaped, colorless to a light color, and 4.4 to 15.0 × 7.0 to 10.0 μm. Sclerotia formed about 1 week later, were black-brown and varied in size (2.0 to 5.0 × 2.0 to 4.0 mm) and shape. The ITS region of rDNA was amplified from DNA extracted from single-spore isolate BC12 of B. cinerea using primers ITS4/ITS5 and sequenced (GenBank Accession No. GU724512), BLAST analysis (1) of the 535-bp segment showed 99% similarity with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). Pathogenicity tests were carried out on healthy schisandra plants that were 4 years old. After the surface of the leaves and fruits was disinfected with 5% sodium hypochlorite, a conidial suspension of 105 conidia/ml was sprayed on 10 schisandra leaves, and plugs of the fungus obtained from the colony margins were transferred onto a 3- × 3-mm wound on the surface of disinfected fruit. Ten control schisandra leaves and 10 fruits were inoculated at the same time. Plants were covered with polyethylene bags and incubated at 25°C in a greenhouse with relative humidity of 85% for 3 days. Similar symptoms to those observed on diseased leaves and fruits in the field were observed on inoculated schisandra leaves and fruits 7 days after inoculation, whereas control leaves and fruits showed no symptoms. The pathogen was successfully reisolated. The gray mold disease caused by B. cinerea was reported in many plants, such as Lavandula stoechas and Chamelaucium uncinatum in Italy (2,3). However, to our knowledge, this is the first report of gray mold disease of schisandra caused by B. cinerea in China.

First Report of Botrytis cinerea Causing Gray Mold of Tobacco in Guizhou Province of China.

Tobacco (Nicotiana tabacum L.) is a leafy, annual, solanaceous plant grown commercially for its leaves. Guizhou Province produces more than 30% of the total Chinese tobacco crop. In July 2010, a disease was observed in a commercial field of 5-month-old N. tabacum plants in Bijie, Guizhou in southwestern China. Symptoms first appeared on the leaves as small spots that later increased in size and developed into expanded, dark brown lesions covered with green-gray spore masses. Lesions expanded rapidly under cool, humid conditions. Isolates of Botrytis cinerea were collected from diseased leaves with typical symptoms. Diseased leaf samples were washed with distilled water three times, placed in a moist chamber, and incubated at 25°C in darkness for 48 h to encourage sporulation. Spores produced on leaves were transferred to individual agar discs (5 mm in diameter) with an inoculating needle and then the agar discs were transferred to potato dextrose agar (PDA) and incubated at 25°C for 7 days. Fungal colonies were at first colorless and later became gray to brown when the conidia differentiated. The size of conidia ranged from 5.0 to 9.5 × 6.5 to 12.5 μm (average 7.3 × 8.7 μm) based on 50 spore measurements. Microsclerotia produced in the culture were round or irregular and ranged from 1.2 to 3.0 × 1.0 to 2.5 mm (average 2.1 × 2.0 mm). The pathogen was identified as B. cinerea Pers.:Fr on the basis of morphology and sequence of ITS1-5.8s-ITS2 region of rDNA amplified by PCR using universal primers ITS-1 (5'-TCCGTAGGTGAACCTGCGG-3') and ITS-4 (5'-TCCTCCGCTTATTGATATGC-3'). The sequence (GenBank Accession No. HQ902163) exactly matched the sequences of two Botryotinia fuckeliana (anamorph B. cinerea) accessions, (e.g., GenBank Accession Nos. HM849615.1 and HM849047.1). Koch's postulates were conducted by wound inoculating five tobacco leaves (cv. K326) after surface disinfesting them with 5% NaOCl. Plugs of the fungus (5 mm in diameter) obtained from the colony margins were transferred onto 3 × 3 mm wounds made with a needle on the surface of five sterilized leaves. Inoculated leaves were incubated at 25°C, 100 to 120 μE·m-2·s-1, relative humidity >80%, and 16 h light per day for disease development. Typical symptoms developed on leaves within 7 days after inoculation. The pathogen was reisolated from affected leaves but not from the noninoculated control leaves. Botrytis gray mold blight has been recorded on N. tabacum in New Zealand, the United Kingdom, and northern China (1-3). However, to our knowledge, this is the first report of Botrytis blight on N. tabacum in Guizhou Province of China and the disease must be considered in existing disease management practices.

Cultural, physiological comparison and fungicidal sensitivity between&lt;br&gt;two isolates of Botrytis cinerea and Stemphylium botryosum

Cultural and physiological comparison between Botrytis cinerea and Stemphylium botryosum causing gray mold in chickpea and stemphylium blight in lentil were studied. Both isolates differed significantly on the basis of their colony diameter, color, texture, shape, margin, conidia dimension, spore production and sensitivity to fungicides. The maximal colony diameter (80.16 mm) and spore (2.7 10 4 ) m L -1 was found in chickpea dextrose agar (CDA) and lentil dextrose agar (LDA) respectively , for Botrytis cinerea . Stemphylium botryosum maximal colony diameter (57.00 mm) and spore (1.7 10 4 ) m L -1 was obtained from LDA. The optimum temperature and pH for Botrytis cinerea and Stemphylium botryosum growth was 20°C and 25°C; pH 4.5 and 5.5, respectively. The conidia size were found to be 11.74 8.12 µm for B. cinerea and 16.27 9.07 µm for S. botryosum . Rovral 50WP from the iprodione group was found to be the most effective chemical fungicide to inhibit the radial mycelial growth of both isolates. Trichoderma harzianum was found to be an effective antagonist against both pathogens.

Genetic differentiation and gene flow in Colletotrichum sublineolum in Ethiopia, the centre of origin and diversity of sorghum, as revealed by AFLP analysis

Isolates of Colletotrichum sublineolum were collected from different sorghum‐producing regions of Ethiopia and divided into five groups based on their geographic origin. The growth rate of 50 isolates showed considerable variation: 1·7–5·8 mm day−1, mean 3·3 mm day−1. However, the isolates displayed little variation in colony colour and colony margin, except for isolates from the north, which were different from the others. Amplified fragment length polymorphism analysis of 102 isolates revealed much greater variations among the different groups. Dice similarity coefficients ranged from 0·32 to 0·96 (mean 0·78). Cluster analysis and principal coordinate analysis revealed a differentiation of the isolates according to their geographic origin, and both methods clearly indicated a genetic separation between the southern, the eastern and the other isolates. Analysis of molecular variance (amova) indicated a high level of genetic variation both among (42%) and within (58%) the C. sublineolum sampling sites in Ethiopia. The amova also indicated a high level of genetic differentiation (FST = 0·42) and limited gene flow (Nm = 0·343). The results of this study confirmed the presence of a highly diverse pathogen, which is in agreement with the existence of diverse host genotypes and widely ranging environmental conditions in sorghum‐producing regions of the country. Such diversity should be taken into account in future breeding programmes to achieve an effective and sustainable disease management strategy.

Botryosphaeria dothidea causing canker of grapevine newly reported in China

In the summer of 2009 in Zhejiang, Jiangsu, Guangxi, Shanxi, Beijing, Tianjin and Hebei Provinces, a decline of grapevines (Vitis vinifera) was identified with symptoms of dieback on one or more shoots, accompanied by elongated oval-shaped cankers in the wood, shrivelling and rot of fruit clusters. A total of 121 diseased samples were collected from affected areas and from these samples more than 1000 infected tissue pieces were used for pathogen isolation. Tissue from the lesion margins was surface-sterilized by placing in 75% ethanol for one min, then rinsing with sterilized water (three times) before placing on potato dextrose agar plates incubated at 28°C for 5 days (Niekerk et al., 2004). Hyphae from the colony margins were transferred to fresh agar plates to obtain pure isolates. Botryosphaeria dothidea was isolated from 44 of the diseased samples. Colonies of B. dothidea were white, becoming grey or dark brown with age. Pycnidia started to develop after 10 days. Conidia measured 17–32 × 4–9 μm. Some isolates were used for ITS sequence analysis to confirm the morphological identification. The primers ITS1 and ITS4 were used to amplify part of the nuclear rDNA operon by PCR (White et al., 1990). Ten ITS sequences were obtained (GenBank Accession Nos. GU226844 to GU226850, GU226852, GU226854 and GU226855). All sequences showed 99–100% homology with B. dothidea (Urbez-Torres et al., 2006). This is the first report of grapevine canker associated with B. dothidea in China. The research was supported by the Earmarked Fund for Modern Agro-industry Technology Research System (Ref. No. nycytx-30).

First Report of Brown Rot Caused by Monilinia fructicola Affecting Peach Orchards in Slovenia.

Monilinia fructicola, the causal agent of brown rot, is a destructive fungal pathogen that affects mainly stone fruits (Prunoideae). It causes fruit rot, blossom wilt, twig blight, and canker formation and is common in North and South America, Australia, and New Zealand. M. fructicola is listed as a quarantine pathogen in the European Union and was absent from this region until 2001 when it was detected in France. In August 2009, mature peaches (Prunus persica cv. Royal Glory) with brown rot were found in a 5-year-old orchard in Goriška, western Slovenia. Symptoms included fruit lesions and mummified fruits. Lesions were brown, round, rapidly extending, and covered with abundant gray-to-buff conidial tufts. The pathogen was isolated in pure culture and identified based on morphological and molecular characters. Colonies on potato dextrose agar (PDA) incubated at 25°C in darkness had an average daily growth rate of 7.7 mm. They were initially colorless and later they were light gray with black stromatal plates and dense, hazel sporogenous mycelium. Colony margins were even. Sporulation was abundant and usually developed in distinct concentric zones. Limoniform conidia, produced in branched chains, measured 10.1 to 17.7 μm (mean = 12.1 μm) × 6.2 to 8.6 μm (mean = 7.3 μm) on PDA. Germinating conidia produced single germ tubes whose mean length ranged from 251 to 415 μm. Microconidia were abundant, globose, and 3 μm in diameter. Morphological characters resembled those described for M. fructicola (1). Morphological identification was confirmed by amplifying genomic DNA of isolates with M. fructicola species-specific primers (2-4). Sequence of the internal transcribed spacer (ITS) region (spanning ITS1 and ITS 2 plus 5.8 rDNA) of a representative isolate was generated using primers ITS1 and ITS4 and deposited in GenBank (Accession No. GU967379). BLAST analysis of the 516-bp PCR product revealed 100% identity with several sequences deposited for M. fructicola in NCBI GenBank. Pathogenicity was tested by inoculating five mature surface-sterilized peaches with 10 μl of a conidial suspension (104 conidia ml-1) obtained from one representative isolate. Sterile distilled water was used as a control. Peaches were wounded prior to inoculation. After 5 days of incubation at room temperature and 100% relative humidity, typical brown rot symptoms developed around the inoculation point, while controls showed no symptoms. M. fructicola was reisolated from lesion margins. Peach and nectarine orchards in a 5-km radius from the outbreak site were surveyed in September 2009 and M. fructicola was confirmed on mummified fruits from seven orchards. The pathogen was not detected in orchards from other regions of the country, where only the two endemic species M. laxa and M. fructigena were present. To our knowledge, this is the first report of M. fructicola associated with brown rot of stone fruits in Slovenia.