[11] Is Transcriptional Regulation of Gravitropism Conserved Between Dicots and Monocots   R.L. Hammond¹, H. Myburg¹, I.Y. Perera¹, C.S. Brown^1,2 and H. Winter Sederoff^1  1Plant Sensory Genomics Group, Dept. of Plant Biology, and ²Kenan Institute for Engineering, Technology & Science, North Carolina State University, Raleigh, NC, 27695.
   Gravity is a constant force that directs the course of plant growth.Plants sense the direction of the gravity vector and respond to changes in orientation by redirecting their growth.  This response to gravity requires specific changes in gene expression to accomplish differential cell elongation.  Previous studies on Arabidopsis root tips (Kimbrough et al. 2004) and the maize pulvinus (Heilmann et al. 2001, Myburg, unpublished) reveal that specific genes are regulated within minutes of gravitropic stimulation.   We are comparing gene expression patterns in response to gravity between maize pulvini and Arabidopsis root tips to identify possible conserved mechanisms.  Conserved and tissue specific gravity induced changes in transcript abundances will further be analyzed for their temporal expression in maize root apices.    In these experiments we will monitor changes in transcript abundances in the maize root over a time course during the first hour after reorientation using real-time PCR.  The expression profile information generated will then be compared between Arabidopsis root tips and the maize pulvinus to assess the level of conservation in transcriptional regulation between dicots and monocots.  

Heilmann, I. Shin, J., Huang, J., Perera, I.Y., Davies, E. (2001)  Transient Dissociation of Polyribosomes and Concurrent Recruitment of Calreticulin and Calmodulin Transcripts in Gravistimulated Maize Pulvini. Plant Physiol. 127:1193-1203.

Kimbrough, J.M., Salinas-Mondragon, R., Boss, W.F., Brown, C.S., Sederoff, H.W.  (2004)  The Fast and Transient Transcriptional Network of Gravity and Mechanical Stimulation in the Arabidopsis Root Apex.  Plant Physiol. 136:2790-2805.

(Supported by NCSU RNA Biology fellowship to R.L.H. and NASA grants NAAG2-1566 to CSB, and NNA04CC56G)