CLONING OF ABC TRANSPORTER-ENCODING GENES IN TRICHODERMA SPP., TO DETERMINE THEIR INVOLVEMENT IN BIOCONTROL

ATP-binding cassette (ABC) transporters are ATP-dependentpermeases which mediate transport of a number of different substratesover biological membranes. The mechanism of resistanceconferred by over-expression of ABC transporter genes relies onincreased energy-dependent efflux, which, in turn, causes decreasedintracellular accumulation of toxicants. We consideredthat ABC transporters of Trichoderma spp. have an importantrole in a number of processes such as resistance to environmentaltoxicants produced either by soil microflora or introduced by humanactivity (e.g. fungicides, heavy metal pollutants), secretion offactors (mycotoxins and cell-wall degrading enzymes) necessaryfor the establishment of a compatible interaction with a host fungusor for the creation of a favourable microenvironment. Wehave cloned four different ABC transporter sequences of Trichodermaatroviride strain P1, named TABC1, TABC2, TABC3 andTABC4. Results of a RT-PCR analysis performed with primersdesigned on TABC2 sequence indicated that this gene is activatedwhen T. atroviride is treated with culture filtrate of Botrytiscinerea, Rhizoctonia solani or Pythium ultimum, or is grown in thepresence of B. cinerea or R. solani mycelia.