Use of High Resolution Spatiotemporal Gene Expression Data to Uncover Novel Tissue-Specific Promoters in Tomato

Genetic modification can be an effective strategy for improving the agronomic traits of tomato ( Solanum lycopersicum ) to meet demands for yield, quality, functional components, and stress tolerance. However, limited numbers of available tissue-specific promoters represent a bottleneck for the design and production of transgenic plants. In the current study, a total of 25 unigenes were collected from an RNA-sequence dataset based on their annotation as being exclusively expressed in five type of tissues of tomato pericarp (outer and inner epidermis, collenchyma, parenchyma, and vascular tissues), and every five unigenes, was respectively selected from each tissue based on transcription expression. The 3-kb 5′ upstream region of each unigene was identified from the tomato genome sequence (SL2.50) using annotated unigene sequences, and the promoter sequences were further analyzed. The results showed an enrichment in T/A (T/A > 70%) in the promoter regions. A total of 15 putative tissue-/organ-specific promoters were identified and analyzed by real-time (RT) quantitative (q) PCR analysis, of which six demonstrated stronger activity than widely used tissue-specific tomato promoters. These results demonstrate how high spatiotemporal and high throughput gene expression data can provide a powerful means of identifying spatially targeted promoters in plants.