Cell-to-Cell and Long Distance Signaling
Chatterjee, Mithu , Banerjee, Anjan, K , Hannapel, David,J .
A mobile RNA exhibits light-activated transcription.
BEL1-like transcription factors interact with their protein partners from the knotted1-family to bind to target genes and regulate numerous developmental and metabolic processes. Recent studies have shown that specific BEL1 mRNAs of potato, designated StBEL5, are involved in a long-distance signaling pathway that mediates tuber induction. The transcriptional source of these mobile RNAs is leaf veins and petioles. Whereas photoperiod mediates the movement of StBEL5 RNA, activation of the StBEL5 gene in leaves is regulated by light, regardless of photoperiod. To define the regulatory elements in this promoter, deletion constructs were designed from the 2.3 kb upstream region of StBEL5, fused with GUS and analyzed in transgenic plants. Upon illumination with either red or blue light, the StBEL5:GUS transgenic lines exhibited induced GUS activity whereas far-red light had no effect. As expected, the StBEL5 promoter harbors conventional light-responsive cis-acting elements like GT1, and G- and I-boxes. In addition to the light regulation, promoter activity was also responsive to GA3 in shoots and wound treatments on stems. Unlike flowering, the signaling pathway for tuber formation arises in a light-grown organ, the leaf, and is transmitted to an underground organ, the stolon. In stolons, the StBEL5 promoter was active in the dark but its activity was repressed when grown in light. This dark activity in stolons and the presence of a tandem TTGAC motif, specific for interaction with the BEL/Knox duplex, on the BEL5 promoter suggest the possibility of auto-regulation.
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1 - Iowa State University, Horticulture, 233, Horticulture hall, Ames, Iowa, 50011, USA
2 - Iowa State University, Horticulture
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM