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Plant Gravitropism and Genomics: What's the difference between "Up" and "Down"? N. Ward1, H. Winter Sederoff1, and C.S. Brown1,2  Plant Gravitational Genomics Group, 1Dept. Botany, and 2Kenan Institute for Engineering, Technology &Science, NC State University, Raleigh, NC.

   Plants have developed roots to grow into the soil where they can take up nutrients, and water, and provide stability. Their shoots however grow up so their leaves have exposure to light for photosynthesis. Plants use the vector of gravity to distinguish "up" from "down". While the hypocotyls are negatively gravitropic, the roots are positively gravitropic, growing towards the vector of gravity. Following a gravity stimulus (reorientation), changes in transcript abundance occur within less than one minute in the Arabidopsis root apex (Kimbrough et al. 2004). We compared the changes in transcript abundance of those very early gravity specific genes in the root apices and hypocotyls of 7 day old dark-grown Arabidopsis seedlings during the first hour of gravity stimulation using real-time PCR.

Kimbrough, J., Salinas-Mondragon, R., Boss, W.F., Brown, C.S., Winter Sederoff, H.(2004)  The fast and transient transcriptional network of gravity and mechanical stimulation in the Arabidopsis root apex. Plant Physiol. (In press).

(Supported by NASA: NAG2-1566)