Stabilities of reference genes play an important role in accurate normalization of gene expression during quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis.To the present, commonly used reference genes are housekeeping genes that are assumed to be constantly expressed.However, recent studies have shown that expression of traditional housekeeping genes may vary in different tissues or under different treatments.For rice study, there is still a lack of systematical validation and recommendation of appropriate reference genes according to the specific experimental condition.