Mycobiota from Cyclamen persicum and its interaction with Botrytis cinerea.

Sixty-six fungi isolated from cyclamen phylloplanes were identified and assessed in vitro for antagonism to B. cinerea on leaves, petals, petioles and peduncles. The estimation of pathogen conidial production was used as indicator of biocontrol ability of each of the strains. They were classified by cluster analysis resulting in four categories according to their behavior in the different organs. The most promising category included 34 isolates that significantly reduced pathogen inoculum in all the organs. Correspondence analysis showed association among leaf isolations, strains of Clonostachys rosea and Penicillium spp. and the best biocontrol performance. The statistical analysis was successful in dealing with this complex set of experimental data. Leaf fungal diversity was higher than those of petals and petiols, with Shannon values of 2.7, 0.9 and 0.5 respectively. Evidence for antibiosis and hyperparasitism was found for C. rosea.

Nigrospora sphaerica Causing Leaf Spot and Twig and Shoot Blight on Blueberry: A New Host of the Pathogen.

Blueberries (Vaccinium corymbosum) have recently become an important alternative crop in different ecological regions of Argentina. In surveys, a new disease characterized by leaf spots and twig and shoot blight has been observed on plants cultivated in Arrecifes, Mercedes, and San Pedro (provinces of Buenos Aires) and Concordia (province of Entre Ríos) since July 2004. Spots initially appear brown, circular, 1 to 2 mm in diameter, and irregularly distributed on the leaves and they eventually coalesce. Fruiting twig and shoot blight developed from the tips toward the base. Affected plants of cvs. O'Neal and Reveille were distributed randomly in the field and with a low incidence (average of 2%). The objective of this work was to identify the causal agent of this disease. Symptomatic plant material was surface disinfested with 0.2% NaOCl for 1 min and 70% ethanol for 1 min, washed once with sterile distilled water, blotted dry with paper towels, and plated on potato dextrose agar. Colonies were initially white, becoming light to dark gray with the onset of sporulation with black, sphaerical to subsphaerical conidia that measured 14 to 19 × 12 to 16 µm. These characteristics agree with published descriptions of Nigrospora sphaerica (Sacc.) Mason (1,4). To evaluate pathogenicity, all leaves, petioles, and stems of seven healthy potted plants of cv. O'Neal were punctured with flamed needles and sprayed with a suspension of 1 × 108 spores of the fungus per milliliter of sterile distilled water. Another seven nonwounded plants were sprayed with the spore suspension. Seven plants similarly injured and seven nonwounded plants were sprayed with sterile distilled water and served as controls. Each plant was covered with a water-sprayed polyethylene bag and maintained in a controlled environment chamber at 20°C with a 12-h photoperiod. The bags were removed after 3 days. All wounded inoculated plants began to show disease symptoms similar to those observed in the field 20 days after inoculation. Controls and nonwounded inoculated plants remained symptomless. The pathogen was reisolated from diseased tissues fulfilling Koch's postulates. N. sphaerica is a well-known saprophyte on many plant species but has been mentioned as pathogen on many hosts (2,3). To our knowledge, this is the first reference of N. sphaerica as a wound pathogen of blueberry. In the field, the fungus would have gained access to the plant through wounds caused by insects or frost after a long-term wetness duration. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN, 1989. (3) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA. 2007. (4) E. W. Mason. Trans. Brit. Mycol. Soc. 12:152, 1927.

The effect of furanoheliangolides from Tithonia diversifolia on superoxide anion generation in human neutrophils.

Four known lactones were isolated from Tithonia diversifolia: furanoheliangolides 1,3-dihydroxy-3,10-epoxy-8-(-2-methylpropanoyloxy)-germacra-11(13)-ene-6,12-olide (1), 1,3-dihydroxy-3,10-epoxy-8-(2-methylpropanoyloxy)-germacra-4,11(13)-diene-6,12-olide (2), 1,3-dimethoxy-3,10-epoxy-8-(2-methylpropanoyloxy)-germacra-4,11(13)-diene-6,12-olide (3) and, observed in natural source for the first time, furanoheliangolide 1-hydroxy-3-methoxy-3,10-epoxy-8-(2-methylpropanoyloxy)-germacra-4,11(13)-diene-6,12-olide (4). The activity of sesquiterpene lactones on superoxide anion (O(2)(o)(-)) generation from PMA-activated neutrophils was evaluated. Compound 1 did not show a full dose dependent behavior. The IC(100) was 8+/-1, 12+/-1, and 17+/-3 microM for 2 to 4, respectively.

First Report of Botrytis Gray Mold on Common Calla Lily in Buenos Aires, Argentina.

Common calla lily (Zantedeschia aethiopica (L.) Spreng., family Araceae) is an evergreen herbaceous South African ornamental plant that forms a tuft of fleshy-stalked, glossy, dark green leaves. At bloom during the summertime, large, funnel-shaped, waxy-white spaths that surround a bright yellow spadix form at the end of high stalks. In August 2003, large, irregular brown spots with a 3- to 4-mm yellow halo were observed on leaves of 10 plants growing near Japanese quince shrubs (Chaenomeles lagenaria (Loisel.) Koidz.) in Escobar, Buenos Aires. Debris of Japanese quince petals were attached to the center of the lesions with profuse sporulation of Botrytis cinerea Pers. (1). Pathogen spores were disposed on potato dextrose agar (PDA) and incubated at 22°C. Mycelium was initially whitish and turned gray with age. Black conidiophores bore botryose heads of hyaline, ellipsoid, unicellular conidia, gray in mass, 7.5 to 10.5 µm × 6.8 to 7.5 (average 9.2 to 7 µm). Black, irregular sclerotia formed at random in culture. Inoculum was prepared from 7-day-old cultures on PDA. Six flowering common calla lilies planted in 5-liter plastic pots were inoculated by spraying a suspension of 2.5 × 106 conidia per ml of sterile distilled water. Six healthy plants were sprayed with sterile distilled water. Each plant was covered with a transparent polyethylene bag for 3 days and kept at 21°C under a 12-h photoperiod. After a 12-day incubation period, leaves showed elliptic to irregular brown spots surrounded by yellow halos. Tiny round to irregular brown spots developed on flower spaths that finally blighted. Water-treated plants remained symptomless. Koch's postulates were fulfilled by pathogen reisolation from diseased organs. To our knowledge, this is the first report of B. cinerea on Z. aethiopica in Argentina. Infection efficiency of B. cinerea increases when inoculated petals are positioned on leaves (2), which has epidemiological importance in landscapes with association of plant species that are potential hosts of this pathogen. Reference: (1) M. V. Ellis and J. M. Waller. No. 431 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1974. (2) C. Sirjusingh et al. Plant Dis. 80:154, 1996.

Asian Soybean Rust: Incidence, Severity, and Morphological Characterization of Phakopsora pachyrhizi (Uredinia and Telia) in Argentina.

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, is the most destructive disease of soybean (Glycine max) in many areas of the world. ASR was first detected in Argentina during 2002 in a limited area in the northern region of the country (2). During the 2004 growing season, P. pachyrhizi spread rapidly throughout most soybean growing areas of northwestern and northeastern Argentina. ASR was also was found in some fields in Entre Ríos and Santa Fe provinces. In all areas, symptoms were expressed late in the 2004 season (growth stages R5.5 to R7) and yield losses were minimal. The objectives of this study were to quantify P. pachyrhizi infection in the canopy and morphologically characterize the fungus from fields where it had been previously detected by polymerase chain reaction (PCR) (3). Incidence (percentage of plants affected) and severity (percentage of leaf area affected, including chlorosis) were visually estimated for 10 plants arbitrarily collected (April 2004) from each of three fields located in Charata (Chacabuco), Chaco Province (Sample 1, collected in the R6 stage), La Paloma (Moreno), Santiago del Estero Province (Sample 2, stage R6 to R7), and Tolloche (Anta), Salta Province (Sample 3, stage R5.5). Disease assessments were made for the lower, middle, and upper canopy from 15 leaves per plant. The number of pustules per cm2 and uredinia per lesion were recorded from the undersides of central leaflets for each trifoliolate observed. Tissue sections were made to observe fructifications of P. pachyrhizi. Incidence of affected plants was 100% in all fields. Disease severity for Sample 1 was 45% (range 30 to 60%), 20% (10 to 30%), and 10% (5 to 20%) for the lower, middle, and upper canopy, respectively; for Sample 2: 60% (30 to 80%), 40% (25 to 50%), and 25% (15 to 40%) for the lower, middle, and upper canopy, respectively; and for Sample 3: 25% (10 to 50%), 15% (10 to 20%), and 10% (5 to 15%) for the lower, middle, and upper canopy, respectively. The number of pustules per cm2 for Sample 1 was 156/cm2 (range 88 to 200); Sample 2: 172/cm2 (128 to 232); and Sample 3: 120/cm2 (72 to 232). The number of uredinia per lesion for Sample 1 was 6 per lesion (range 1 to 15); Sample 2: 5.5 per lesion (1 to 13), and Sample 3: 2.8 per lesion (1 to 5). The two spore types that were commonly observed were urediniospores and teliospores. Telia were found on infected leaves mixed with uredinia in every sample. Urediniospores measured 16 to 22 µm (mean 18.5 µm) × 25 to 30 µm (mean 27 µm). Teliospores measured 8 to 11 µm (mean 9 µm) × 19 to 27 µm (mean 23.8 µm). Spores sizes are in the range described by Ono et al. (1). To our knowledge, this is the first report of epidemiological and morphological characterization of ASR in Argentina and the first report of the telial stage of P. pachyrhizi on soybean in South America. References: (1) Y. Ono et al. Mycol. Res. 96:825, 1992. (2) R. L. Rossi. Plant Dis 87:102, 2003. (3) SINAVIMO, Sistema Nacional Argentino de Vigilancia y Monitoreo de plagas. Roya de la soja: Resultados de la campaña 2003-2004. On-line publication. SENASA, 2004.

Hydrangea macrophylla Flower Spot Caused by Botrytis cinerea in Buenos Aires.

During the spring of 2003, flower spots were observed on French hydrangea (Hydrangea macrophylla (Thunb.) DC) in CETEFFHO-INTA-JICA experimental greenhouses in Castelar, Argentina. Brown, irregular spots randomly distributed on petals were detected on an old, whiteflowering variety of unknown origin, cultivated by growers. Small pieces of diseased tissue were surface disinfested with 2% NaOCl, plated on 2% potato dextrose agar (PDA) with pH 7, and incubated at 22 to 24°C. Dense, whitish mycelium developed within 48 h and turned gray after 72 h. Conidia were ellipsoid, hyaline, nonseptate, and formed in botryose heads. Spores from 10-day-old colonies that were developed on PDA in test tubes were removed with 4 ml of sterile water per tube. Prior to inoculation, inflorescences were detached and placed in water-filled glass vases. To test pathogenicity, eight healthy inflorescences were sprayed with a 5-ml suspension (2 × 104 conidia per ml of sterile distilled water). Another eight healthy inflorescences were sprayed with sterile distilled water. The inflorescences were maintained at 21°C and covered with polyethylene bags that were removed after 3 days. Brown, circular-to-irregular spots appeared on petals 5 days after inoculation, became coalescent, and covered 50 to 60% of each inflorescence in 8 days. Gray mold consisting of black conidiophores and gray-in-mass conidia was observed 3 days after the development of the symptoms. Controls remained symptomless. The same pathogen was recovered from inoculated flowers and was identified as Botrytis cinerea Pers.:Fr. (1). To our knowledge, this is the first report of this fungus on Hydrangea macrophylla in Argentina. Reference: (1) M. V. Ellis and J. M. Waller. Sclerotinia fuckeliana (condial state: Botrytis cinerea).No. 431 in: Descriptions of Pathogenic Fungi and Bacteria, CMI, Kew, Surrey, UK, 1974.

First Report of Botrytis cinerea on Pansy Flowers in Buenos Aires.

Pansy (Viola × wittrockiana) is an ornamental annual plant produced as a potted plant in greenhouses around Buenos Aires, Argentina. Flower rot with signs of gray mold was observed on pansy cv. Crown during the autumn of 2003. Diseased tissues were surface sterilized by immersion in 2% NaOCl for 1 min, placed on 2% potato dextrose agar (PDA), and incubated at 22°C. Fungal mycelia were initially white and became gray after 72 h. After 4 days, colonies were 4 cm in diameter and sporulated profusely. Black sclerotia developed after 7 days. Mycelia were septate with dark branched conidiophores bearing unicellular, ellipsoid, hyaline conidia that measured 8 to 12 × 6 to 8 µm in botryose heads. These characteristics agree with Botrytis cinerea Pers.:Fr. (1). Pathogenicity tests were performed by spraying 10 healthy pansy plants during bloom with 3 ml of a conidial suspension (106 conidia per ml) per plant. Controls were treated with sterilized distilled water only. Plants were covered with plastic bags for 2 days and incubated at 18 to 22°C. The flowers developed water-soaked lesions between 4 and 6 days after inoculation. Fifty percent of the flowers were pendulous because flower blight reached the peduncle. The pathogen was reisolated from diseased flowers after superficial sterilization with 2% NaOCl and isolated on PDA. Gray mold has a rapid development during bloom, and the pathogen was able to enter undamaged flower tissues. No disease symptoms were observed on leaves. This report adds pansy as a new host of B. cinerea to a previous list of ornamentals grown in Argentina where gray mold was observed. Reference: (1) M. V. Ellis and J. M. Waller. Sclerotinia fuckeliana (condial state: Botrytis cinerea). No. 431 in: Descriptions of Pathogenic Fungi and Bacteria, CMI, Kew, Surrey, UK, 1974.

Synthesis and theoretical study of 2-amino-2,3,3a,4,5,6-hexahydro-1H-phenalene and its biological evaluation on central dopaminergic system.

Compound 2 considered as a rigid non-hydroxylated 2-amino tetralin was synthesized and biologically evaluated. Central administration of compound 2 (50 microg or 100 microg/10 microl) induced a reduction in urinary sodium and potassium excretion at 3 and 6 h of urine collection. We speculate that compound 2 may be acting as a dopamine receptor antagonist.

First Report of Alternaria Leaf Spot of Spathiphyllum sp. in Argentina.

Brown necrotic spots surrounded by chlorotic areas have been observed on the leaf margins of Spathiphyllum sp. in many nurseries in and near Buenos Aires, Argentina, since 1997. Spots reached 0.7 × 2 cm and appeared mainly on older leaves of stressed plants. To determine the causal agent of the leaf spot, small pieces of diseased tissue were surface-sterilized for 2 min in 2% sodium hypochlorite and plated on potato dextrose agar. Gray olivaceous to almost black colonies developed in 3 to 4 days. Dark conidiophores, which formed singly or in small groups, were short, less than 100 µm, sometimes flexuous, and occasionally geniculate. The brown to black, obclavate, pyriform, or rostrate conidia were 20 to 25 µm long × 10 to 15 µm wide, with three to four transverse septa and one to three longitudinal or oblique septa. Chains of conidia 5 to 10 spores long were sometimes branched, appearing bushy. The foliage of 15 healthy potted plants previously injured with sterile needles and 15 healthy potted plants without injuries was inoculated with a suspension of 2.8 × 104 conidia per ml. Plants were maintained at 23°C and 100% relative humidity under fluorescent light (12 h light/12 h darkness) for 3 days. Chlorotic and necrotic spots began to develop on the apex and margins of injured and inoculated leaves after 10 days. Lesions tended to coalesce, finally measuring 2.2 × 0.7 cm after 26 days. Control plants, with and without injuries, sprayed with distilled water remained symptomless. Koch's postulates were satisfied after reisolating the fungus. Cultures in potato carrot agar and V8 agar after 7 days exhibited typical characteristics of Alternaria alternata (2-4). An Alternaria sp. has been found previously in the United States on Spathiphyllum sp. (1). This is the first report of Alternaria leaf spot of Spathiphyllum in Argentina. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN. (2) E. G. Simmons. Alternaria themes and variations (226-235): Classification of Citrus pathogens. Mycotaxon 70:263, 1999. (3) E. G. Simmons. Alternaria themes and variations (236-243): Host specific toxin producers. Mycotaxon 70:325, 1999. (4) E. G. Simmons and R. G. Roberts. Alternaria themes and variations (73). Mycotaxon 48:109, 1993.

Mycotoxin production by Alternaria alternata strains isolated from red delicious apples in Argentina.

Eleven Alternaria alternata strains isolated from Red Delicious apples in cold storage in Argentina, were tested for alternariol and alternariol methyl ether production in laboratory media and in whole fresh fruits. Most of them were able to produce both toxins in all media. They were detected also in mycelium free filtrates from liquid cultures and in asymptomatic tissues from inoculated fruit. Thus, in the evaluation of mouldy core incidence in apples, the presence of A. alternata toxins in tissues should be considered even in the absence of mycelia.