The lue1 mutant exhibits altered cell elongation in response to GA. (A,B) GA treatment promotes flowering in lue1. (A) 35-day-old lue1 mutants control or sprayed with 10 μM GA₃ or GA₄ every 4 days. (B) Flowering time of WT and lue1 plants control or sprayed with 10 μM GA₃ every 4 days until bolting. (C) WT and lue1 leaf elongation upon GA₃ treatment. Petiole and blade measurements were performed on adult plants by selecting the longest leaf of control or GA₃-treated WT and lue1 plants (n minimum=30).

Lue1 responses to ACC application are partially compromised. (A-E) Seedlings were grown in the dark on MS plates with or without 50 μM ACC. (A) 3-day-old WT and lue1 seedlings. Hook angle (B), hypocotyl thickness (C), hypocotyl length (D) and root length (E) of WT and lue1 seedlings (n minimum=40). (B-E) ⋄, WT control;□ , WT+ACC; ♦, lue1 control; ▪, lue1+ACC. (F,G) 4-day-old seedlings grown under light conditions on low nutrient medium plates with or without 50 μM ACC. (F) Hypocotyl length. (G) Root length.

Lue1 exhibits disorganized CMF and CMT. (A,B) Polarizing microscopy of WT and lue1 CMF orientation in different cell types. (A) CMF orientation in single pitted vessel cells of WT and lue1 showing maximum birefringence for rotation angles relative to main growth axis of 45° and 0°, respectively. This indicates a transverse orientation of CMF compared with the main growth axis in WT, whereas the average CMF orientation in lue1 is 45°. Bars represent 5 μm. (B) Deviation from transverse orientation of CMF in WT and lue1 cells (n minimum=20). (C-F) Confocal microscopy of CMT organization in WT and lue1 cells. Bars represent 10 μm. The microtubule-decorating GFP-MAP4 reporter was introduced in lue1 by crossing and CMT organization assessed in segregating F₂ seedlings. WT epidermal root (C) and stomata (E) cells. Lue1 epidermal root (D) and stomata (F) cells.

The AtKSS-GFP-GUS protein fusion decorates CMT. (A) Schematic representation of the CaMV35S-AtKSS-GFP-GUS reporter construct introduced into Arabidopsis. (B) Ectopic expression of the AtKSS-GFP-GUS (AtKSS-G-G) protein fusion in Arabidopsis Col0 ecotype phenocopies the lue1 phenotype. (C) Differential interference contrast (DIC) reference images of D. (D-K) Confocal microscopy of AtKSS-G-G subcellular distribution. GFP fluorescence is encoded in the green channel. Bars represent 10 μm. (D,E) Root epidermis cells close to the root tip. (F,G) Root epidermis cells distal from tip. (H) Hypocotyl. (I,J) Transition zone between root and hypocotyl. (K) Stomata.