Figure 1: Phenotype of almt1 and stop1 mutants and expression of ALMT1.
From: Low phosphate activates STOP1-ALMT1 to rapidly inhibit root cell elongation
(a) Position and nature of the almt1 and stop1 mutations. (b) Appearance of representative WT and mutant seedlings after germination and growth for 6 days on +Pi or −Pi medium. (c) Primary root length of WT (Coler105) and mutant seedlings grown for 6 days in +Pi or −Pi conditions. Mean±s.d., n=9–14 seedlings per line and condition; unpaired two-tailed t-test; ****P<0.0001). (d) Malate complementation. WT and almt1 seedlings grown under +Pi for 2 days were transferred for 6 days to −Pi medium with or without the indicated concentrations of malate (mean±s.d., n=7–14 seedlings per condition; two-way ANOVA, ****P<0.0001; ***P<0.001; **P<0.01; *P<0.05; NS, not significant). (e) Gene expression analysis. WT seedlings grown under +Pi for 5 days were transferred to +Pi or −Pi medium for 1–48 h, total root RNA was extracted and expression of the indicated genes analysed by qRT–PCR. SPX1 was used as a positive marker for the −Pi stress. Relative expression levels are normalized to that of the +Pi at 1 h (mean±s.e.m., n=6 independent experiments; unpaired two-tailed t-test; **P<0.01; *P<0.05; NS, not significant). (f) Pattern of ALMT1 expression in primary root tip. Transverse (top) and longitudinal (bottom) sections of the root tip of pALMT1::GUS (WT). Seedlings were grown 5 days under +Pi and transferred to +Pi or −Pi medium for 48 h prior to GUS staining. (g) GFP-fluorescence of GFP-STOP1 in root tips. Four-day-old stop1KO;pSTOP1::GFP-STOP1 (# B10A) seedlings grown under +Pi were transferred to +Pi or −Pi plates for 24 h, and GFP-fluorescence was visualized by confocal microscopy. Left panel: the two roots were mounted side by side on the same microscope slide (× 10 objective). Middle panel: magnification of the root tips (× 20 objective). See also Supplementary Fig. 6c for additional lines. Right panel: intensity of the GFP-fluorescence (a.u., arbitrary units) in nuclei of the root tip (mean±s.d., n=54 and 43 nuclei in + Pi and −Pi, respectively; unpaired two-tailed t-test; ****P<0.0001). Two (c,d,f) or three (g) independent experiments were performed with consistent results and one representative experiment is shown. Scale bars, 1 cm (b), 100 μm (f,g).
