| Auxin controls a range of growth related characteristics by a mechanism dependent upon polar auxin transport. We have identified a leaf vein patterning mutant that shows a simple first leaf vein pattern. The veins are often non-meeting and form somewhat parallel to one another. The leaves are narrow and pointed so that the overall phenotype is reminiscent of grass leaves hence the mutant name grassy (gsy). A range of shoot and root characteristics are also altered in gsy plants. Compared to wild type, gsy plants have shorter primary roots with reduced numbers of lateral roots and increased numbers of longer root hairs. Upon gravitropic stimulation, the root tip bends slightly away from the normal vector. As well, gsy plants produce an inflorescence with altered internode elongation and branching pattern. The intensity of the auxin responsive reporter gene DR5::GUS is unchanged in both roots and developing leaves of gsy, however, it shows subtle differences to the wild type DR5:GUS expression pattern. Finally, gsy leaf and root phenotypes are more sensitive to low doses of the auxin efflux inhibitor NPA and external auxin 2, 4-D. We suggest that this overall pattern is consistent with defects in auxin transport. |
