Abstract:Positive controls were important for quality identification in microarray analysis of gene expression profiles. Two most important house-keeping genes GAPDH and APRT in plant often serve as positive standards. Here partial cDNAs of GAPDH （GenBank accession number：EF189713）and APRT（GenBank accession number： EF189712） were amplified from Erianthus arundinaceus by reverse transcriptase-polymerase chain reaction (RT-PCR) using two pairs of primers designed according to the corresponding sequence of Zea mays. Four sets of E. arundinaceus under PEG-stress were applied to the cDNA microarray hybridization using the two genes as positive controls. Profiles showed that the average values of singal to noise (S:N) of Cy5 and Cy3 were 56.12 and 60.8 in GAPDH, respectively, while 51.06 and 47.25 in APRT, respectively. High signal was detected in all the hybridization, with the values of over 10 000 in GAPDH and 8 000 in APRT, indicating reliable hybridization. Both GAPDH and APRT expressed more stably than BADH. It is suggested that the two house-keeping genes from E. arundinaceusis are suitable for positive controls in genechip applification.