Leaf surface and endophytic fungi associated with onion leaves and their antagonistic activity against Alternaria porri.

Abstract

Sixty-eight fungal species belonging to 29 genera were isolated as leaf surface and endophytic fungi from healthy and purple blotch diseased onion leaves. The fungal populations associated with diseased onion leaves (1.360 × 10 3 CFU/g leaf in the phyllosphere, 2.614 CFU/leaf segment in the phylloplane and 1.324 CFU/leaf segment in the surface-sterilised diseased leaves) were higher than those in healthy samples (0.804 × 10 3 CFU in the phyllosphere, 1.184 CFU in the phylloplane, and 0.35 CFU as endophytes). Endophytic fungi of healthy leaves were represented by 12 genera and 15 species, while fungi of surface-sterilised diseased leaves included 17 species from 13 genera. The mycobiota associated with surface-sterilised diseased leaves were different from the endophytic fungi of healthy samples, whereas the disease may stimulate colonisation of opportunistic fungi causing secondary infections such as Botrytis cinerea, Penicillium aurantiogriseum, Alternaria alternata and Cladosporium spp. In contrast, healthy leaves were a source of antagonistic endophytic fungi such as Trichoderma harzianum and T. koningii. Testing the antagonistic effect of 91 fungal isolates against Alternaria porri showed that nine isolates of Trichoderma produced the highest suppressive potential (73.1%) depending on competition and mycoparasitism. Epicoccum nigrum and Penicillium oxalicum exhibited antibiosis against A. porri producing a 12 mm broad inhibition zone. In conclusion, the quantitative and qualitative compositions of fungi associated with onion leaves were distinctly influenced by A. porri infection. Mycobiota associated with asymptomatic onion leaves such as Epicoccum nigrum, Penicillium oxalicum and Trichoderma harzianum are a natural source of eco-friendly bioagents. They showed an effective antagonistic potential against A. porri, and may thus be applied as an alternative to fungicides.

Application of ZnO-nanoparticles to manage Rhizopus soft rot of sweet potato and prolong shelf-life

“…Rotten sweet potato tubers were washed and then cut into sections to reveal the region of rot. The tuber sections were surface sterilized by dipping completely in 70% ethanol for 1 min., 1% NaOCl solution for 3 min., 70% ethanol for 30 s. and, finally, rinsed once in sterilized distilled water (Abdel-Hafez et al, 2015). The tuber sections were placed on sterile filter paper in a laminar airflow chamber for 10 min.…”

Induction of defense mechanisms involved in disease resistance of onion blight disease caused by Botrytis allii

“…Onion leaves, showing Botrytis onion umbel blight "BOUB" disease symptoms, were collected from different localities of onion seed production in Assiut governorate, Egypt. Isolation was carried out from the diseased leaves as described by Abdel-Hafez et al (2015). Leaves were cut into small pieces, thoroughly washed with tap water, and sterilized for 2 min in 2% sodium hypochlorite solution.…”

The Effect of Endophytic Talaromyces pinophilus on Growth, Absorption and Accumulation of Heavy Metals of Triticum aestivum Grown on Sandy Soil Amended by Sewage Sludge

“…Inoculation of the host Glycine max L. plants with P. funiculosum during Cu stress (100 µM) was used to test the endophyte-metal-plant interaction [19]. Talaromyces pinophilus was found to be a common phyllosphere, phylloplane and endophyte in different medicinal plants in earlier studies [20][21][22]. Due to the presence of bioactive substances, T. pinophilus has commonly been utilized as an endophyte [23,24].…”