RT-PCR confirmed that genes identified by microarray were highly but variably expressed in reproductive organs according to the developmental stage and tissue. Total RNA was isolated from various organs (R, root; S, stalk; L, leaf; F, flower) during different developmental stages (green bud, showing color, expanding, full bloom), and from various parts of the flower (lip, callus, reproductive column, and sepal and petal). The genes included Oncidium Expansin (OnExpansin), Oncidium Disease Resistant Response Protein (OnDRRP) and Oncidium Trypsin inhibitor (OnTI1, OnTI2, and OnTI3). Each experiment was carried out in triplicate. Ubiquitin was used to measure the amount of RNA used for each RT-PCR reaction.