The SphI/SalI pRBP-KO fragment was used for transformation of A. fumigatus (akuAKU80 pyrG-) protoplasts. Through the PCR screening of transformants, a deletion strain was isolated and examined further. In this transformant, RBP-F1 and RBP-R1 primers amplified a fragment of ~4.6 kb (KO) instead of a 3.8-kb wild-type fragment, confirming the replacement of native gene with disrupted one (Fig. 1C). RT-PCR analysis of the deletant revealed that AfuRbp does not express in this mutants (data not shown). The growth phenotype of this mutant in various media containing different carbon and nitrogen sources was similar to the parental strain, indicating that AfuRbp is not essential in A. fumigatus. In PCR screening of RNAi transformants, one positive integrant was selected. This transformant was grown in glaA-inducing medium containing 1% maltodextrin, as the sole carbon source. Semi-quantitative RT-PCR analysis using primers RPB-rt1 and RBP-rt2 showed the down-regulation of AfuRbp expression in the presence of maltodextrin (Fig. 1D). Phenotypic analysis of this transformant in inducing medium re-confirmed the non-essential role of AfuRbp in fungal growth.