Poster: Tropisms

Abs # 413: Localization of IRP1 mRNA in gravistimulated maize pulvini

Presenter:	Clore, Amy M, clore@ncf.edu
Authors	Tinnirello, Stella A (A)   Clore, Amy M (A)
Affiliations:	(A): New College of Florida

The maize (Zea mays) stem pulvinus is a valuable system in which to study plant gravitropism. The pulvini are regions of tissue, found just apical to each node, that return the tipped stem to a more upright position via differential cell elongation on the lower side. We sought to identify changes in gene expression that occur in gravistimulated pulvini prior to any visible changes in growth, which occur several hours after reorientation. To this end, we performed suppressive subtractive hybridization PCR in order to amplify fragments corresponding to genes that are up-regulated after one hour of reorientation. One gene we identified has high sequence similarity to IRP1 (iron regulatory protein 1), which is known to regulate the stability and translational efficiency of mRNAs related to iron metabolism in animals. We then performed in situ hybridization experiments to localize IRP1 mRNA and found the gene to be expressed in the bundle sheath cells of the pulvini, which are thought to be the sites of gravity perception. Future work will involve monitoring the location of expression over a more extensive time course and investigating the potential function of IRP1 in the gravitropic response.