Marine isolates of Trichoderma as halotolerant agents of biological control for arid-zone agriculture.
Gal-Hemed, I., Atanasova, L., Komon-Zelazowska, M., Druzhinina, I.S., Viterbo, A. and Yarden, O., 2011
Appl. Environ. Microbiol., 2011 Jun 10. [Epub ahead of print]
The scarcity of fresh water in the Mediterranean region necessitatesthe search for halotolerant agents of biological control ofplant diseases that may be applied in arid-zone agricultureirrigated with saline water. Among 29 Trichoderma strains previouslyisolated from Mediterranean Psammocinia sp. sponges, the greatestnumber of isolates belong to the T. longibrachiatum - H. orientalisspecies pair (9), H. atroviridis/T. atroviride (9) and T. harzianumspecies complex (7), all known for high mycoparasitic potential.In addition, one isolate of T. asperelloides and two putativenew species, T. sp. O.Y. 14707 and O.Y. 2407 from section Longibrachiatumand Strictipilosa clade respectively, have been identified.In vitro salinity assays showed that the ability to tolerateincreasing osmotic pressure (halotolerance) is a strain- orclade-specific property rather than a feature of a species.Only a few isolates were found to be sensitive to increasedsalinity while others were either halotolerant or even demonstratedimproved growth in increasingly saline conditions. In vitroantibiosis assays revealed strong antagonistic activity towardsphyopathogens, due to the production of both soluble and volatilemetabolites. Two marine derived Trichoderma isolates, identifiedas T. atroviride and T. asperelloides respectively, effectivelyreduced Rhizoctonia solani damping off disease on beans andalso induced defense responses in cucumber seedlings againstPseudomonas syringae pv. lachrimans This is the first inclusiveevaluation of marine fungi as potential biocontrol agents.