Abstract
A mechanism which enables shoots and roots to grow toward various angles relative to gravity vector, such as ortho-, plagio- and diagravitropisms, has been poorly understood in contrast to mechanisms involved in gravity perception, establishment of lateral gradient of auxin concentration, and subsequent bending of plant organs found in orthogravitropism.
Growth orientation of roots along curvilinear length was measured based on images of Arabidopsis roots grown on vertically-held solid media. We observed that lateral roots of wild-type Columbia bent vertically downward before reaching 5 mm in length in contrast to those of mutant hy5 maintaining slanted growth orientations.
We are applying various drugs, such as auxin or auxin polar transport inhibitors, to hy5 and wild-type and analyzing growth orientations of lateral roots. Expression of the DR5 auxin reporter and auxin efflux facilitators is also being determined in root system. By examining these factors, mechanisms of plagiogravitropism will be discussed.
