Aspergillus terreus Inhibits Growth and Induces Morphological Abnormalities in Pythium aphanidermatum and Suppresses Pythium-Induced Damping-Off of Cucumber

Abstract

The study investigated the efficacy of two isolates of Aspergillus terreus (65P and 9F) on the growth, morphology and pathogenicity of Pythium aphanidermatum on cucumber. In vitro tests showed that the two isolates inhibited the growth of P. aphanidermatum in culture. Investigating P. aphanidermatum hyphae close to the inhibition zone showed that the hyphae showed abnormal growth and loss of internal content. Treating P. aphanidermatum with the culture filtrate (CF) of A. terreus resulted in significant rise in cellular leakage of P. aphanidermatum mycelium. Testing glucanase enzyme activity by both A. terreus isolates showed a significant increase in glucanase activity. This suggests that the cell walls of Pythium, which consist of glucan, are affected by the glucanase enzyme produced by A. terreus. In addition, Aspergillus isolates produced siderephore, which is suggested to be involved in inhibition of Pythium growth. Also, the CFs of 65P and 9F isolates significantly reduced spore production by P. aphanidermatum compared to the control (P < 0.05). In bioassay tests, the two isolates of A. terreus increased the survival rate of cucumber seedlings from 10 to 20% in the control seedlings treated with P. aphanidermatum to 38–39% when the biocontrol agents were used. No disease symptoms were observed on cucumber seedlings only treated with the isolates 65P and 9F of A. terreus. In addition, the A. terreus isolates did not have any negative effects on the growth of cucumber seedlings. This study shows that isolates of A. terreus can help suppress Pythium-induced damping-off of cucumber, which is suggested to be through the effect of A. terreus and its glucanase enzyme on P. aphanidermatum mycelium.

Cyanide degradation and antagonistic potential of endophytic Bacillus subtilis strain BEB1 from Bougainvillea spectabilis Willd

“…These results are in agreement with the findings of Hajlaoui et al (1992) who reported that the yeast like antagonistic fungus (Garg et al 2010). The observed loss of turgidity of hyphae of the pathogenic fungi in the inhibition zone suggests alterations in the permeability of the cell membrane (Halo et al 2018). The hyphal malformations may be attributed to production of antibiotic substances by Bacillus sp.…”

Talaromyces variabilis interferes with Pythium aphanidermatum growth and suppresses Pythium-induced damping-off of cucumbers and tomatoes

“…Previous studies showed that Streptomyces hydrogenans culture filtrates inhibited the growth of Alternaria Brassicicol 31 . Oospore production was greatly decreased in the presence of culture filtrates of 48 P and 28 R. Similar observation was made by 16 , where Aspergillus terreus affected spore production by P . aphanidermatum .…”

“…Several endophytic fungi are used as biocontrol agents against plant disease such as Botryosphaeria ribis , Trichoderma sp. and Aspergillus terreus 14,16 . Talaromyces species have multiple benefits for plants; they have been used as biocontrol agents against several plant pathogen 17,18 .…”

Alternaria alternata and Neocosmospora sp. from the medicinal plant Euphorbia larica exhibit antagonistic activity against Fusarium sp., a plant pathogenic fungus

“…Ezziyyani et al (2007), while studying the interaction between the pathogenic fungus, Phytophthora capsici and the antagonist, Trichoderma harzianum also observed deformation, disintegration and vacuolization of P. capsici hyphae. The disintegration of hyphae of the pathogenic fungi in the inhibition zone in this study suggests alterations in the permeability of the cell membrane (Halo et al 2018).…”