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Abstract Detail


Tropisms

Doore, Sarah [1], Clore, Amy M. [2].

Changes in the Levels of Expression of a Cytoplasmic Aconitase/IRP1 Homologue in Gravistimulated Maize Pulvini.

The maize (Zea mays L.) stem pulvinus is a graviresponsive disc of tissue located apical to each node that functions to return a tipped stem to a more upright position via increased cell elongation on its lower side. In preliminary studies, we determined that a maize cytoplasmic aconitase/iron regulatory protein 1 (IRP1) homologue is upregulated in the pulvinus bundle sheath cells after gravistimulation by using both northern analysis and in situ hybridization. However, these techniques were of limited utility for getting a comprehensive picture of the kinetics of expression. Therefore, we employed real time reverse transcriptase PCR (real time RT-PCR) to quantify the levels of the corresponding mRNA in the upper and lower halves of the pulvini harvested along a time course of gravistimulation. We found that the levels of the aconitase/IRP1 homologue expression underwent synchronous rises and falls in the two halves over the first few hours following reorientation of the plants with respect to the gravity vector. In contrast, mRNA levels were relatively steady in tipped internode tissue and in vertical pulvini harvested at comparable times of day. Although we do not yet know the role of the IRP1 homologue in the pulvinus, the protein is known to be a redox sensor in other systems, which is consistent with our previous findings that levels of ROS increase in the pulvinus bundle sheath cells following gravistimulation. Much research in both animals and plants also indicates a role for cytoplasmic aconitase/IRP1 in RNA binding and gene expression regulation. Our future work will focus on the study of the protein and its localization, as well as roles it may play in RNA binding and redox regulation in the pulvinus system. Real time PCR machine purchase was made possible by NSF MRI Award DBI-0520607, while funding for reagents was generously provided by the New College of Florida Foundation and the Division of Natural Sciences.


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1 - New College of Florida, Division of Natural Sciences
2 - New College of Florida, Division of Natural Sciences, 5800 Bayshore Rd., Sarasota, FL, 34243, U.S.A.

Keywords:
cytoplasmic aconitase
maize
IRP1
real-time RT-PCR
gravitropism
pulvinus.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P32008
Abstract ID:1468


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