Trichoderma is a well-known antagonist against soilborne plant pathogens. However, the species and even various isolates have different biocontrol potential. To evaluate the antagonistic activities of Trichoderma harzianum, T. harzianum strain T100 (T100), T. viride and T. haematum against Fusarium oxysporum and F. proliferatum, we used dual culture and productions of volatile and non-volatile metabolites in three different phases in vitro. An analysis of the data in dual culture tests represented T. viride, T. haematum and T100 as effective antagonists of Fusarium while T100 was the only fungus being able to lyse the confronting mycelia. Similar results were obtained in the volatile metabolites tests also. In contrast with the two previous tests, the non-volatile metabolites produced by T. harzianum inhibited Fusarium mycelial growth the most, and T100 acted moderately. It was also clearly showed that the antagonistic effect of Trichoderma spp. was more on F. proliferatum than on F. oxysporum. Finally, because Trichoderma spp. was most effective in the second phase, we recommend to use T100 against F. proliferatum at the initial stages of infection as its mycoparasitism on F. oxysporum was observed microscopically through forming apressoria structures without any coiling around the pathogen.
Fusarium proliferatum, as a toxigenic fungus, is one of the important agents of onion basal rot (FBR). Among the control methods of the disease, biological control is considered as one of the best options. In this study, Trichoderma harzianum strain T100 at the rate of 1 × 10 6 cfu/g was mixed with pot soil artificially infested with F. proliferatum. Also Glomus mosseae was applied to each pot at the rate of three grams of soil containing 80 chlamydospores/ml. Combination of T100 and G. mosseae was used as well. Onion seeds were disinfected & planted in pots, arranged in completely randomized design in 4 replicates under greenhouse condition and finally, the individual or combined effects of these bioagents were assessed on FBR control and also root colonization by Glomus 23, 30 and 36 days after sowing. Inoculation of Arbuscular mycorrhizae improved onion growth effectively, but its biocontrol effect was not considerable. Trichoderma amended soil decreased disease incidence by 25% but its usefulness as biocontrol agent was reduced in the course of time. AM root colonization was decreased in plants in presence of Trichoderma. Nevertheless, the disease control in combination of Trichoderma and Glomus treatment was better than the treatments by each one of the agents singly. The disease control achieved by fungicide seed treatment was inferior to that of Trichoderma and Glomus in combination.
Although Iran represents one of the presumed centers of domestication of grapevines, there is a huge paucity of knowledge on yeast species diversity on grapevines in Iran. This study was performed to explore the species diversity amongst the epiphytic and endophytic yeast community
on grape berries in Iran. Five different regions were selected for sampling. Out of 59 collected samples, 352 yeast isolates were recovered, of those 315 isolates were epiphytes and 37 isolates were endophytes. Species were identified by a combination of M13 fingerprinting and sequencing the
D1/D2 region of 26SrDNA. Twenty three different species were identified as epiphytes and 74% of them were Ascomycota. Among these species, seven (all ascomycetous) were also isolated as endophytes. Hanseniaspora uvarum was the predominant species both in epiphyte and endophyte detection
and had the highest biodiversity (H') and evenness index (E). Other species such as Pichia terricola, Metschnikowia sinensis and Aureobasidium pullulans were the further most frequently isolated species. This is the first report of Candida membranifaciens
as inhabitants of grape berries.
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