Phylogeny and antagonistic activity of some protoplast fusants in Trichoderma and Hypocrea

Abstract

The present work aimed to apply mutagenesis and inter-specific protoplast fusion techniques of two locally isolated Hypocrea and Trichoderma to enhancement their biocontrol abilities against some important plant fungal pathogens which cause damping-off diseases that attacking different crops. The mutants were selected after EMS/UV treatment of Trichoderma isolates. The obtained protoplasts were fused by polyethylene glycol, and six fusants were selected for further studies. The phylogeny of the parental strains was carried out using sequence of ITS region. The BLAST of the obtained sequence was identified these isolates as H. koningii and T. asperellum. The fused protoplasts of the two mutant strains have been regenerated on PDA medium supplemented with the two fungicides. Most of the fusants exhibited fast mycelial growth on PDA as compared to parent strains. The obtained results indicated that partial or incomplete genetic recombination may be possible during nuclear and cytoplasmic protoplast fusion. Most of the fusants have shown powerful antagonistic activity against the grapevine pathogens as Pythium ultimum and Fusarium roseum as shown in dual culture and observed by SEM technique. Results of the present study demonstrated the scope and significance of the protoplast fusion technique, which can be used to develop superior hybrid strains of filamentous fungi that absent sexual stages in Trichoderma enhance biological control activity.

Influence of Protoplast Fusion in Trichoderma Spp. on Controlling Some Soil Borne Diseases

“…However, other author found a relationship between RAPD polymorphisms of Trichoderma strains and their antagonism against Aspergillus niger [29]. Moreover, the others found a high relationship between some molecular markers of Trichoderma strains and their antagonism against many plant pathogens as Fusarium oxysporium, Pythium altimum and Sclerotium rolfsii [5,8,24,30]. Moreover, here and in a previous study, T. harzianum was the predominant taxon, T. harzianum is the most commonly reported species in the genus, occurring in diverse ecosystems and ecological niches.…”

“…The enzyme reacted with the cell wall of mycelial mass became swelled up and round hyaline globules by the from 40% to 60% of PEG is suitable for protoplasts fusion in different fungi [23,24]. However, Pe'er and Chet [18], used 33% PEG for protoplast fusion in T. harzianum.…”

“…If one colony has a faster growth rate than the other, a curve in the inhibition zone will be observed easily. However, if the two inoculations have the same growth rate, a straight line would be observed when mycelia from both fungi come into contact [6,24].…”

“…Therefore, can be used for integrated disease management of soil borne plant pathogens. The degree of antagonism varied between and within strains of Trichoderma against the soil borne plant pathogens [6,19,24,26].…”

“…However, Pe'er and Chet [18], used 33% PEG for protoplast fusion in T. harzianum. Therefore, concentration of PEG is highly critical for effective fusion of protoplasts [5,24].…”