Expression array for Trichoderma harzianum T34 and nox1 overexpressed transformant Tnox5 strains in dual culture with Pythium ultimum

A self-designed Trichoderma high density oligonuclotide (HDO) microarray (Roche-NimbleGen, Inc., Madison, WI, USA) was constructed in a similar way than a previous Trichoderma HDO microarray (Samolski et al., 2009). The microarray was composed of 392,779 60-mer probes designed against 13,443 EST-derived transcripts (Trichochip-1) and the genomes of T. atroviride (11,100 genes) and T. virens (11,643 genes). The Trichochip-1 ESTs were obtained from 28 cDNA libraries from eight different species (representing the biodiversity of this genus: T. harzianum, T. atroviride, T. asperellum, T. viride, T. longibrachiatum, T. virens, T. stromaticum and T. aggresivum), under a wide range of growth conditions, including biocontrol-related conditions and different nutritional situations (Vizcaíno et al., 2006). The Trichochip1 EST database was generated in the TrichoEST project funded by the EU (QLK3-CT-2002-02032). Confrontations were carried out between the T. harzianum T34 or nox1 overexpressed transformant Tnox5 and P. ultimum. Agar plugs cut from the growing edge of a 4-day colony of Trichoderma and Pythium were placed 2 cm from the border on the opposite side of the same petri plates containing PDA covered with sterile cellophane sheets. Dual cultures were allowed to grow at 25 ºC and mycelia were collected from the interaction zone in confrontations between P. ultimum and T. harzianum T34 or Tnox5 strains. Seven PDA plates were used for each condition considered and RNAs were extracted and the corresponding cDNAs were use to hybridize by triplicate the Trichoderma HDO microarray.