Promoter activity of polypyrimidine tract-binding protein genes of potato responds to environmental cues

• Published in: Planta 2012-12, Vol.236 (6), p.1747-1755
• Main Authors: Butler, Nathaniel M., Hannapel, David J.
• Format: Article
• Language: English
• Subjects: Agriculture; Base Sequence; Biological and medical sciences; Biomedical and Life Sciences; Cloning, Molecular; Conserved sequence; Cytosine; Drought; Droughts; Ecology; Environment; Forestry; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Glucuronidase - metabolism; Heat; Leaves; Life Sciences; Light; Light effects; Lycopersicon esculentum - genetics; Mesophyll; Molecular Sequence Data; Nucleotide sequence; Original Article; Petioles; Phloem; Plant Sciences; Plant Tubers - genetics; Plant Tubers - growth & development; Plant Tubers - metabolism; Plant Tubers - physiology; Plants; Plants, Genetically Modified; Polypyrimidine Tract-Binding Protein - genetics; Polypyrimidine Tract-Binding Protein - metabolism; Potatoes; Promoter Regions, Genetic - genetics; Promoters; PTB protein; Regulatory sequences; RNA; RNA binding proteins; RNA-binding protein; Sequence Alignment; Sequence Analysis, DNA; Solanum tuberosum; Solanum tuberosum - genetics; Solanum tuberosum - growth & development; Solanum tuberosum - metabolism; Solanum tuberosum - physiology; Splicing; Sprouts; Stems; Sucrose; Temperature; Transgenic plants; Tubers; Uracil; Vegetables; Veins
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-012-1726-7

Polypyrimidine tract-binding (PTB) proteins are RNA-binding proteins that target specific RNAs for post-transcriptional processing by binding cytosine/uracil motifs. PTBs have established functions in a range of RNA processes including splicing, translation, stability and longdistance transport. Six PTB-like genes identified in potato have been grouped into two clades based on homology to other known plant PTBs. StPTBl and StPTB6 are closely related to a PTB protein discovered in pumpkin, designated CmRBP50, and contain four canonical RNA-recognition motifs. CmRBP50 is expressed in phloem tissues and functions as the core protein of a phloem-mobile RNA/protein complex. Sequence from the potato genome database was used to clone the upstream sequence of these two PTB genes and analyzed to identify conserved cw-elements. The promoter of StPTB6 was enriched for regulatory elements for light and sucrose induction and defense. Upstream sequence of both PTB genes was fused to ß-glucuronidase and monitored in transgenic potato lines. In whole plants, the StPTB1 promoter was most active in leaf veins and petioles, whereas StPTB6 was most active in leaf mesophyll. Both genes are active in new tubers and tuber sprouts. StPTB6 expression was induced in stems and stolon sections in response to sucrose and in leaves or petioles in response to light, heat, drought and mechanical wounding. These results show that CmRBP50-like genes of potato exhibit distinct expression patterns and respond to both developmental and environmental cues.