Identification and validation of organ-preferential genes and analysis of corresponding upstream tissue-specific promoters in wheat

Tissue/organ-specific promoters are important tools in genetic engineering and crop molecular breeding. They are well characterized in dicots, such as Arabidopsis, tobacco, and tomato, but not sufficiently in monocots, especially in wheat. In this study, the genes specifically expressed in seven different tissues, including coleoptile, root, leaf, pistil, anther, embryo, and endosperm were identified through analyzing the public transcriptome data from a wheat microarray using the ROKU method. The expression patterns of selected genes were validated by reverse transcription polymerase chain reaction. The results showed that these selected genes were expressed specifically or preferentially in each representative tissue/organ. Moreover, the function of their promoters was verified by transient expression in wheat or stable transformation in Arabidopsis. The results showed that these promoters can efficiently and predominantly drive uidA (β-glucuronidase) reporter gene expression in different tissues. Due to their tissue-specific nature, these promoters can be used as potential candidates in plant genetic engineering.