Plant Biotechnology 23, 413–417 (2006)

To establish a transient gene expression system for investigating the molecular function of genes in mature wheat seeds, we bombarded embryos or aleurones of three hexaploid wheat (Triticum aestivum L.) varieties Chinese Spring, RL4137 and OS21-5, two diploid wheat (T. monococcum L.) varieties KT3-1 and KT3-5 and a barley (Hordeum vulgare, L.) variety Himalaya with fusion constructs containing the GUS reporter gene driven by the Actin1 promoter or a-amylase promoter using a particle gun, and compared the efficiency of gene expression for the transient assay. The efficiency of transient expression was high in aleurone tissues of OS21-5, KT3-1, KT3-5 and Himalaya. In the aleurone tissues of KT3-5, the a-amylase promoter was especially markedly activated by gibberellic acid (GA) and by a GA-inducible MYB transcription activator of T. monococcum, TmGAMYB. This assay system using the aleurone tissues of KT3-5 may be especially useful for investigating which genes are expressed and how they are regulated in germinating wheat seeds.