Thus, it would appear that
gravitropic responses and chemotropic responses to low and high P status soil influence the architecture of the root system and root hair development.
Sowings were made monthly from September 2010 to August 2011 (totaling 12 sowings) and the germination (protrusion and
gravitropic curvature of the primary root) was followed over 30 days period.
Control roots underwent a high rate of
gravitropic curvature, which decreased with an increased density of the external medium.
The phenomenon of root
gravitropic curvature is a three part process: gravity perception in the cap via a starch statolith-based gravisensor; signal transduction resulting in the modification of basipetal auxin flux patterns; and downward curvature due to differential growth rates on the upper and lower root surfaces.
Root gravitropism is the tendency of a root to grow at a specific orientation with respect to gravity, or
Gravitropic Setpoint Angle ("GSA," Firn and Digby, 1997).
Although the
gravitropic and gravitactic responses of plants to changes in gravity were discussed at this meeting, the responses of animal cells to gravity are not well documented.
These results indicated that auxin-induced NO and cGMP mediate
gravitropic curvature in soybean roots.
We find that these shoots are both negatively
gravitropic as well as positively phototropic.
Pulse- chase studies done using [[3.sup]H]-IAA indicate that the polar auxin transport was increased in gps1 after gravistimulation at 4[degrees]C, although the mutant showed no
gravitropic bending under these conditions, gps2 shows normal polar auxin transport even though it bends in the opposite direction.