Scanning electron microscopy observations of the interaction betweenTrichoderma harzianumand perithecia ofGibberella zeae

Abstract

Chronological events associated with the interaction between a strain of Trichoderma harzianum, T472, with known biological control activity against perithecial production of G. zeae, were studied with scanning electron microscopy to investigate the mechanisms of control. Large clusters of perithecia consisting of 5-15 perithecia formed on the autoclaved, mulched wheat straw inoculated with G. zeae alone (control) with an average of 157 perithecia per plate. Small clusters consisting of 3-6 and an average of 15 perithecia per plate perithecia formed on straw that was treated with T. harzianum. The mature perithecia from straw treated with T. harzianum produced less pigment and were lighter in color than those from the control plates. Furthermore the cells of the outer wall of these perithecia were abnormal in appearance and unevenly distributed across the surface. Immature perithecia were colonized by T. harzianum approximately 15 d after inoculation (dai) with the biocontrol agent and pathogen. Few perithecia were colonized at later stages. The affected perithecia collapsed 21 dai, compared to the perithecia in the control samples that began to collapse 28 dai. Abundant mycelium of T. harzianum was seen on the perithecia of treated samples. Perithecial structures may be resistant to penetration by the mycelium because direct penetration was not observed. Trichoderma harzianum colonized the substrate quickly and out-competed the pathogen, G. zeae.

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“…With good colonization capacities, can compete with the development of pathogens. It can form a mechanical barrier that physically blocks the development of pathogenic fungi and is also be able to establish connections between its hyphae and those of pathogens through the formation of haustaurium [31]. When in contact with pathogens, it can also synthesize compounds that degrade the fungal walls, probably chitinases, preventing the progression of pathogens.…”

The potential of antagonistic fungi for control ofFusarium graminearumandFusarium crookwellensevaries depending on the experimental approach

“…Following an antagonist treatment, perithecia were frequently rather small, flat and appeared like immature perithecia. Inch and Gilbert () conducted scanning electron microscopy studies on the interaction between T. harzianum (strain T472) and G. zeae with simultaneous inoculation. Perithecia colonised by the antagonist produced less pigment, the outer wall was thinner and cells had an abnormal, smoothened appearance in contrast with the marbled surface of unaffected perithecia.…”

Biocontrol Agents: Toolbox for the Screening of Weapons against Mycotoxigenic Fusarium

“…Xeda was also able to directly attack the formed mature perithecia. Coculture of F. graminearum perithecia with other Trichoderma species also showed decreases in pigment production, and the outer wall of the perithecia are deformed [107]. Poly severely limits the formation of perithecia and covers those that have been formed, mainly due to its strong expansion capacity.…”