In vitro screening of the effect of three glucosinolate derived nitriles on soil-borne fungi

Glucosinolates are allelochemicals present in all plants of the order Capparales that are hydrolysed by endogenous enzymes (myrosinases) forming a variety of compounds with biological activity. ‘Biofumigation’ is the term used to describe the effect of these compounds on soil-borne pathogens and it has normally been attributed to isothiocyanates. At acidic pH and in the presence of redox co-factors such as glutathione, glucosinolate hydrolysis yields also nitriles, which are more hydrophilic and stable than isothiocyanates. Three nitriles (allyl-, benzyl- and phenethyl cyanide) were tested against soil borne fungi of economic importance: Aphanomyces euteiches var. pisi, Gaeumannomyces graminis var. tritici and Verticillium dahliae. The nitriles were initially tested at 1 mM and four additional concentrations were further tested in order to determine LD50. At 1 mM, allyl cyanide showed in all cases less than 10% inhibition and it did not inhibit fungi growth at higher concentrations. LD50 of benzyl cyanide was 2.5 mM for Verticillium and Aphanomyces, whereas it was as low as 0.5 mM for Gaeumannomyces. LD50 of phenyl ethyl cyanide was 2.5 mM for Verticillium, 1.4 mM Gaeumannomyces and 1.25 mM Aphanomyces. Although nitriles are generally less toxic than ITCs, their role in biofumigation should not be disregarded

The rhizosphere: a playground and battlefield for soilborne pathogens and beneficial microorganisms

The rhizosphere is a hot spot of microbial interactions as exudates released by plant roots are a main food source for microorganisms and a driving force of their population density and activities. The rhizosphere harbors many organisms that have a neutral effect on the plant, but also attracts organisms that exert deleterious or beneficial effects on the plant. Microorganisms that adversely affect plant growth and health are the pathogenic fungi, oomycetes, bacteria and nematodes. Most of the soilborne pathogens are adapted to grow and survive in the bulk soil, but the rhizosphere is the playground and infection court where the pathogen establishes a parasitic relationship with the plant. The rhizosphere is also a battlefield where the complex rhizosphere community, both microflora and microfauna, interact with pathogens and influence the outcome of pathogen infection. A wide range of microorganisms are beneficial to the plant and include nitrogen-fixing bacteria, endo- and ectomycorrhizal fungi, and plant growth-promoting bacteria and fungi. This review focuses on the population dynamics and activity of soilborne pathogens and beneficial microorganisms. Specific attention is given to mechanisms involved in the tripartite interactions between beneficial microorganisms, pathogens and the plant. We also discuss how agricultural practices affect pathogen and antagonist populations and how these practices can be adopted to promote plant growth and health

Viljan tyvitautien esiintyminen Etelä-Suomessa vuosina 1975-1978

vokKirjasto Aj-

Generic names in Magnaporthales

This is the final version of the article. Available from the publisher via the DOI in this record.The order Magnaporthales comprises about 200 species and includes the economically and scientifically important rice blast fungus and the take-all pathogen of cereals, as well as saprotrophs and endophytes. Recent advances in phylogenetic analyses of these fungi resulted in taxonomic revisions. In this paper we list the 28 currently accepted genera in Magnaporthales with their type species and available gene and genome resources. The polyphyletic Magnaporthe 1972 is proposed for suppression, and Pyricularia 1880 and Nakataea 1939 are recommended for protection as the generic names for the rice blast fungus and the rice stem rot fungus, respectively. The rationale for the recommended names is also provided. These recommendations are made by the Pyricularia/Magnaporthe Working Group established under the auspices of the International Commission on the Taxonomy of Fungi (ICTF).This work was partially supported by the National Science Foundation of the United States (grant number DEB 1145174 and DEB 1452971) to Ning Zhang

Molecular and morphological characterization of Pyricularia and allied genera

The phylogenetic relationships of Pyricularia species and species from related genera were established from sequences of the internal transcribed spacer ribosomal RNA gene. Phylogenetic analysis disclosed a consistent correlation with spore morphology. Most Pyricularia species studied, and two species of Dactylaria that have obpyriform conidia, fell within the Magnaporthaceae cluster with high bootstrap support. Pyricularia variabilis was more related to Dactylaria, Tumularia or Ochroconis species than to the Magnaporthaceae. Dactylaria and species of Nakataea, Ochroconis, Pyriculariopsis and Tumularia were distinct from the Magnaporthaceae, and the genus Dactylaria is polyphyletic. The combination of morphological and molecular characters, such as spore morphology and ITS ribosomal DNA sequences data, suggested that conidial shape could be a primary character to distinguish Pyricularia from related genera.published_or_final_versio

Антагонистическая активность штамма Pseudomonas fluorescens 2303 по отношению к фитопатогенам

Досліджено антагонізм штаму Pseudomonas fluorescens 2303 стосовно фітопатогенних бактерій і грибів. Цей штам пригнічував розвиток P.syringae pv. syringae 8511, P.syringae pv. atrofaciens 9400, Xantomonas campestris 8003б, Clavibacter michiganensis 102 — зони затримки росту становили 20—40 мм. Штам P.fluorescens 2303, на відміну від штамів препарату гаупсин, пригнічував розвиток таких фітопатогенних бактерій, як Pectobacterium carotovorum 8982 та Agrobacterium tumefaciens 8626. Штам P.fluorescens 2303 виявився високоактивним стосовно фітопатогенних грибів і був, у середньому, в два рази активнішим за штам препарату для захисту рослин — гаупсину. Зокрема, індекс пригнічення розвитку збудника офіобольозної кореневої гнилі Gaeumannomyces graminis var. tritici 10Z у 9,4 разу перевищував відповідне значення для гаупсину. За результатами проведених досліджень штам P.fluorescens 2303 є перспективним для застосування у сільському господарстві для комплексного захисту рослин від фітопатогенних грибів та бактерій, а також для розроблення препарату на основі цього штаму.In this paper, we study the antagonism of Pseudomonas fluorescens 2303 strain on pathogenic bacteria’s and fungi’s. This strain inhibited the development of P.syringae pv. syringae 8511, P.syringae pv. atrofaciens 9400, Xantomonas campestris 8003b, Clavibacter michiganensis 102 — stunting zones were 20—40 mm. Strain P.fluorescens 2303, unlike the product haupsyn, inhibited the growth of pathogenic bacteria such as Pectobacterium carotovorum 8982 and 8626 Agrobacterium tumefaciens. P.fluorescens 2303 strain was highly active against phytopathogenic fungi and was on average two times more active than the strain of plant protection product — gaupsin. In particular, the inhibition index of root rots caused by Gaeumannomyces graminis var. tritici 10Z is 9,4 times higher than the corresponding value for gaupsin. The research into P.fluorescens 2303 strain is promising for its applying in agriculture for comprehensive plants protection of plants against pathogenic fungi and bacteria, as well as for developing a product based on this strain.Исследован антагонизм штамма Pseudomonas fluorescens 2303 по отношению к фитопатогенным бактериям и грибам. Данный штамм подавлял развитие P.syringae pv. syringae 8511, P.syringae pv. atrofaciens 9400, Xantomonas campestris 8003б, Clavibacter michiganensis 102 — зоны задержки роста составляли 20—40 мм. Штамм P.fluorescens 2303, в отличие от штаммов препарата гаупсин, подавлял развитие таких фитопатогенных бактерий, как Pectobacterium carotovorum 8982 и Agrobacterium tumefaciens 8626. Штамм P.fluorescens 2303 оказался высокоактивным по отношению к фитопатогенным грибам и был, в среднем, в два раза более активный чем штамм препарата для защиты растений — гаупсина. В частности, индекс угнетения развития возбудителя офиоболезной корневой гнили Gaeumannomyces graminis var. tritici 10Z в 9,4 раза превышал соответствующее значение для гаупсина. По результатам проведенных исследований штамм P.fluorescens 2303 является перспективным для использования в сельском хозяйстве для комплексной защиты растений от фитопатогенных грибов и бактерий, а также для разработки препарата на основе данного штамма

Biological activity of glucosinolate derived compounds isolated from seed meal of Brassica crops and evaluated as plant and food protection agents

Glucosinolates are amino acid derived allelochemicals characteristic of plants of the order Capparales. These compounds are present in seeds of agriculturally common Brassica crops in varying quantities depending on the species (ref). The use of the remaining seed cake after oil extraction has traditionally been limited by the concentration of these compounds. However, the extraction of glucosinolates from seed meal is nowadays possible and it further contributes to an increased quality of the seed meal for feed (Sørensen et al., this conference). Glucosinolates are hydrolysed by endogenous enzymes (myrosinases; EC 3.2.1.147) and a number of compounds are produced depending on the parent glucosinolate and the environmental conditions.1 Among these compounds, oxazolidine-2-thiones are known for their antinutritional effects on monogastric animals, whereas isothiocyanates are fungicidal, nematocidal and herbicidal.2,3 The possibility for using glucosinolates as precursors for environmental friendly biocides therefore exists, which could contribute to increase the value of the Brassica seed meal

Viljan tyvissä ja juuristossa esiintyvä sienistö Etelä-Suomen pelloilla

vokKirjasto Aj-

Mycoviruses are common among different species of endophytic fungi of grasses

8 páginas, 1 tabla, 1 figuraA survey of mycoviruses was made in a collection of 103 isolates belonging to 53 different species of endophytic fungi of grasses. DsRNA elements were detected in isolates of 12 of the species analyzed. The banding characteristics and sizes of some of the dsRNA elements suggest that they might belong to previously described mycovirus families. The observed incidence (22.6%) indicates that the presence of mycoviruses could be common among species of this group of ubiquitous fungi.This research was financed by project AGL2005-02839 granted by the Spanish Ministry of Science and Education. We thank Drs. Robert Coutts and Beatríz R. Vázquez de Aldana for reviewing the manuscript.Peer reviewe

Identifying environmental drivers of fungal non-pollen palynomorphs in the montane forest of the eastern Andean flank, Ecuador

Samples taken from sedimentary archives indicate that fungal non-pollen palynomorphs (NPPs) can be used to provide information on forest cover, fire regime, and depositional environment in the eastern Andean flank montane forest of Ecuador. Within the 52 samples examined, 54 fungal NPP morphotypes are reported, of which 25 were found to be previously undescribed. Examination of fungal NPPs over a gradient of forest cover (2–64%) revealed three distinct assemblages: (1) low (Neurospora, IBB-16, HdV-201, OU-102, and OU-110 indicative of an open degraded landscape; (2) medium (8–32%) forest cover Cercophora-type 1, Xylariaceae, Rosellinia-type, Kretzschmaria deusta, Amphirosellinia, Sporormiella, and Glomus suggestive of a forested landscape disturbed by herbivores and soil erosion; and (3) high (32–63%) forest cover Anthostomella fuegiana, OU-5, OU-101, OU-108, and OU-120. Environmental variables for forest cover (forest pollen), available moisture (aquatic remains), regional fire regime (microcharcoal), and sediment composition (organic carbon) were found to explain ~40% of the variance in the fungal NPP data set. Fire was found to be the primary control on fungal NPP assemblage composition, with available moisture and sediment composition the next most important factors