Figure 1.
Interaction between auxin and glucose in lateral root formation.
A. Acetocarmine-stained root with many lateral root (LR) and lateral root primordia (LRP, red cells). Inset: a single LRP (arrow). B. Acetocarmine-stained root grown with may lateral roots emerged. C. Three-dimensional representation of the effect of auxin and glucose on the formation of LR and LRP (combined). The data were fitted to a model as described in Methods. D. The auxin dose response for LR+LRP production at 4 concentrations of glucose. Inset, the same except expanded in range and number of auxin concentrations and performed with only 2 doses of glucose. E. The glucose dose response for LR+LRP production at 4 concentrations of auxin. The error bars represent the 95% Wald confidence intervals.
Figure 2.
The role of the heterotrimeric G protein complex in the bimodality of auxin-induced lateral root formation.
A. 3-dimensional representation the effect of auxin and glucose on the formation of lateral root primordia and emergent lateral roots (LR+LRP) in wild type (light grey) and seedlings lacking an intact heterotrimeric G protein complex (dark grey). B. Expanded auxin dose response for LR+LRP production at 2 concentrations of glucose for wild type (Col, open squares) and the gpa1-4,agb1-2 double mutant (solid squares). C–E. Auxin dose response for LR+LRP production in wild type (Col, solid line) and seedlings lacking a single component of the G protein complex (dashed lines): gpa1-4 mutant (C), agb1-2 (D), and rgs1-2 (E). The error bars represent the 95% Wald confidence intervals.
Figure 3.
The effect of glucose and the role of the heterotrimeric G protein on lateral root primordia formation (LRP) and lateral root (LR) emergence.
A–B. Auxin dose response for LRP production (A) and LR emergence (B) at 0% glucose (open circles) and 1% glucose (solid circles) for wild type (Col) seedlings. C–D. Auxin dose response for LRP production (C) and LR emergence (D) at 0% glucose for the double gpa1-4,agb1-2 mutant (solid circles) and for wild type (Col) seedlings (open circles). The error bars represent the 95% Wald confidence intervals E. A speculative model consistent with the present and published data. The gray box represents the data published by Mudgil and coworkers [32]. The evidence for each of the signaling elements and the stimulatory and inhibitory arrows is described in the Discussion section. *GPA1, activated (GTP-bound) Gα subunit; GPA1/AGB1/AGG, heterotrimer.