Figure 6.

Induction of ABA pools and ABA signaling in shoots by water-stressing roots. Seedlings of lines pRD29B::LUC and pRD29B::GUS were exposed to water stress (Ψ = −0.8 MPa) via the roots for 24 h prior to the analysis of shoots and roots. The analysis included determination of ABA levels (A), GUS reporter activity (B), and LUC activity (C), with both reporters assayed enzymatically in tissue extracts, and light emission analyzed ratiometrically by in vivo measurement (D). The values are shown for water-stressed seedlings (black bars) and controls (white bars) of either the pRD29B::LUC (A, C, and D) or pRD29B::GUS (B) line. The values are given relative to the highest value obtained within one type of analysis for better comparison with 100% marking in 148 fmol ABA μg protein⁻¹ (A; this equals 164 nmol ABA kg⁻¹ shoot fresh weight or 435 nmol ABA kg⁻¹ root fresh weight), 8.12 RLU s⁻¹ μg protein⁻¹ (B), 1,890 RLU s⁻¹ μg protein⁻¹ (C), and 31 CCD-RLU s⁻¹ μg protein⁻¹ (D). The analysis was performed on 3 groups of 15 seedlings per data point (± sd).