Plant Health and Rhizosphere Microbiome: Effects of the Bionematicide Aphanocladium album in Tomato Plants Infested by Meloidogyne javanica

The artificial introduction in the soil of antagonistic microorganisms can be a successful strategy, alternative to agrochemicals, for the control of the root-knot nematodes (Meloidogyne spp.) and for preserving plant health. On the other hand, plant roots and the associated rhizosphere constitute a complex system in which the contribution of microbial community is fundamental to plant health and development, since microbes may convert organic and inorganic substances into available plant nutrients. In the present study, the potential nematicidal activity of the biopesticide Aphanocladium album (A. album strain MX-95) against the root-knot nematode Meloidogyne javanica in infected tomato plants was investigated. Specifically, the effect of the A. album treatment on plant fitness was evaluated observing the plant morphological traits and also considering the nematode propagation parameters, the A. album MX-95 vitality and population density. In addition, the treatment effects on the rhizosphere microbiome were analysed by a metabarcoding procedure. Treatments with A. album isolate MX-95 significantly decreased root gall severity index and soil nematode population. The treatment also resulted in increased rhizosphere microbial populations. A. album MX-95 can be favourably considered as a new bionematicide to control M. javanica infestation.

REGULATION OF THE DEVELOPMENT OF FUSARIOUS DRYING AND MELOYDOHYNOSIS ON THE MELON WITH THE CHITINOLYTIC MUSHROOM APHANOCLADIUM ALBUM MX-95

The use of biological agents is one of the promising strategies for the regulation of populations of pests that have the least impact on the environment. An experiment using the chitinolytic fungus Aphanocladium album MX-95 (AA MX-95) was carried out on melon plants in a greenhouse with a natural background infection of Fusarium oxysporum f. sp. melonis and the Southern Gall nematode Meloidogyne incognita in Valenzano (Province of Bari, Apulia). A suspension of MX-95 isolate (2 x 107 CFU / mL) was added at a concentration of 2.5 l / plot using plastic tubes fitted with water emitters (according to each melon plant in the row). The suspension of the fungus was added 2 weeks before planting and after planting 3 times every 2 weeks. There was also an option with processing only after landing (3 treatments). Control options included untreated soil and a soil with a diazomet (600 kg / ha), distributed 30 days before planting. Versions with AA MX-95 significantly reduced fusarial wilt, especially when the treatment was before and after planting, much more effective than with chemical control of the diazomet (fungicide and nematicide). The effect of the fungus, introduced before and after planting, was especially manifested in the development of meloydohynosis. The index of galling and the population number of nematodes at the end of the experiment in the soil were reduced by 50 and 63%, respectively, compared with the control. The effectiveness of the AA MX-95 applied before and 3 times after planting was similar and did not differ from the chemical standard diazomet.

Efecto de la temperatura y la salinidad sobre la viabilidad y producción de conidios en los hongos entomopatógenos tolypocladium cylindrosporum y aphanocladium album (deuteromycotina. Hyphomycetes).

Dos cepas antárticas de Hongos entomopatógenos, de Tolypoclodium cylindrosporum y Aphanocladium album, aislados de mosquitos, fueron examinados para observar su respuesta frente a rangos de temperatura y salinidad, en la producción y viabilidad de propágulos de dispersión.Los dos hongos exhibieron una amplia gama de tolerancia a la temperatura (5-35 Cº) y salinidad (0-7% NaCl), mostrando algunas variaciones en cada caso.

Efecto comparativo de la virulencia de los hongos Aphanocladium album (preuss) Gams y Tolypocladium cylindrosporum Gams (Deuteromycotina- Hyphomycetes), contra larvas de mosquito (Diptera, Culicidae)

El presente trabajo ha sido realizado con el objeto de evaluar el efecto potencial patogénico de conidios y blastosporas de Aphanocladium album y Tolypocladium cylindrosporum contra larvas de Culex pipiens L.Un alto porcentaje de mortalidad larval se observó frente a las 2 especies fúngicas, siendo para A.album, 85,6% y para T.cylindrosporum 80%, con dosis de 1 x 106 conidios/ml.En A. album la actividad de blastosporos y conidios fué similar, mientras que para T. cylindrosporum fueron más virulentos los conidios que las blastosporas.De los resultados obtenidos se deduce que ambas especies fúngicas tienen una elevada virulencia contra larvas de C. pipiens y sus potencialidades patogénicas justifican nuevos estudios sobre este tema.

Aphanocladium album by via sub-irrigation in the control of Pyrenochaeta lycopersici and Meloidogyne incognita on tomato in a plastic-house

Two experiments were carried out to assess the efficacy of different chemicals (azoxystrobin, fosthiazate, metham-sodium) and of the chitinolytic fungus Aphanocladium album (isolate MX-95), that could be alternatives to methyl bromide, against the soil borne pathogen Pyrenochaeta lycopersici and the root-knot nematode Meloidogyne incognita on tomato in a plastic house in southern Italy. In the first trial, the treatments were azoxystrobin (1.25 l a.i. /ha), fosthiazate (1.5 l a.i. /ha) and biological control agent Aphanocladium album isolate MX-95 (2.5 l/plot at 2×107 CFU/ml; plot surface 96 m2). In the second experiment, treatments were metham-sodium (1000 l c.p./ha) and A. album (5 l/plot at 1×107 CFU/ml). In both trials, chemicals and the fungus were applied by via sub-irrigation. Satisfactory control of the corky root and the root-knot nematode attack and a significant yield increase were obtained by application of azoxystrobin, fosthiazate and metham-sodium. A significant reduction of M. incognita soil population density occurred in plots treated with A. album. Also, high positive correlations were found between the symptoms caused on tomato roots by M. incognita and P. lycopersici.

Characterization of N-acetyl-D-glucosamine uptake in Aphanocladium album

A mutant of the fungus Aphanocladium album, characterized as chitinase-overproducing, does not grow on medium containing N-acetyl-D-glucosamine as sole carbon source. The lack of growth may indicate a defect either in the uptake system or in any subsequent step in the metabolism of N-acetyl-D-glucosamine. Since transport is the first step at which control of metabolism could operate, the mutant strain was studied for its ability to transport N-acetyl-D-glucosamine. The results were compared with those obtained with the wild-type strain. Labelling experiments, designed to characterize N-acetyl-D-glucosamine uptake, indicated that uptake was due to the simultaneous operation of two transport systems, one of high affinity and one of low affinity. Wild-type and mutant strains displayed different Km values for the low-affinity system. The Km value of the mutant's low-affinity system was very high compared with that of the wild-type strain.Key words: deuteromycete, filamentous fungus, Aphanocladium album, uptake, N-acetyl-D-glucosamine.

A β-1,3-D-endo-mannanase from culture filtrates of the hyperparasites Verticillium lecanii and Aphanocladium album that specifically lyses the germ pore plug from uredospores of Puccinia graminis f.sp. tritici

The hyperparasites Verticillium lecanii (Zimm.) Viegas syn. Verticillium hemileiae and Aphanocladium album (PreuB) W. Gams are capable of penetrating the hyphal walls and uredospores of the stem rust fungus Puccinia graminis f.sp. tritici, their potential host. The culture filtrates of both hyperparasites contain an array of polysaccharide-degrading enzymes that in concert, digest the walls of uredospores completely. We have now isolated an enzyme with β-1,3-D-endo-mannanase activity that is secreted by both hyperparasites into the culture medium in the presence of autoclaved walls of uredospores as a carbon source. The β-mannanase predominately lyses the germ pore plugs of uredospores as shown by electron scanning microscopy. The enzyme has an apparent molecular mass of 19 000 Da as revealed by medium pressure liquid chromatography using a Superose 12 gel filtration column. An enzyme with identical specificity was found in dormant and soaked uredospores. Since opening of the germ pore plug is a very early and crucial step in germination of uredospores, the implication of β-mannanases in the germination process is discussed. Key words: Aphanocladium album, germination, β-mannanase, hyperparasitism, Puccinia graminis, Verticillium lecanii.