A Suite of Crop Promoters with Precise Organ-Specific Expression Patterns

The successful deployment of crop biotechnology to improve disease resistance, abiotic stress tolerance, or other desirable traits requires the ability to precisely control the expression of transgenes. Currently, only a few transgene expression control elements (i.e. promoters), which drive gene expression in a tissue- or organ-specific manner, are available from crop plants. We have identified and characterized a collection of promoters that confer distinct leaf-, root-, pollen-, seed- or fruit-specific patterns of expression in transgenic plants. The candidate promoters were selected based on gene expression profiling data and the corresponding upstream promoter sequences were fused to a reporter gene and transformed into rice, Brachypodium, wheat, tobacco, tomato and/or Arabidopsis plants. Two green tissue specific promoters predominantly expressed in rice leaves show light responsiveness and four additional rice promoters exhibit cell type specificity within the roots of transgenic plants. Three rice promoters with pollen-specific expression have been characterized and used to successfully ablate transgenic pollen in Brachypodium. In addition, five fruit-specific promoter candidates from citrus have been isolated and characterized. Together, these novel promoters form a useful molecular tool box enabling precise, spatially-defined transgene expression of introduced traits within biotech crops.