Endogenous ECT1 has negligible ECT2/3/4-like function, despite similar expression pattern and subcellular localization.

(A-D) Expression pattern of ECT1p:gECT1-TFP (gDNA) in aerial organs (A), main root (B), lateral root primordia (C) and emerging lateral roots (D) of 10-day-old seedlings. The expression mimics the pattern observed for ECT2/3/4 (Arribas-Hernández et al., 2020). (E-F) Intracellular localization of ECT1-TFP in meristematic cells of root tips in unchallenged conditions. Although the cytoplasmic signal is largely homogenous (E), sporadic foci (F) are frequently observed. S13A Fig shows the integrity of the fluorescently tagged protein in independent transgenic lines assessed by protein blot. (G) Schematic representation of the ECT1 locus. Exons are represented as boxes and introns as lines. The positions and identifiers of the T-DNA insertions assigned to the ect1-1, ect1-2 and ect1-3 alleles are marked, and the location of qPCR amplicons and hybridization probes (P) for analyses is indicated below. Genotyping of ect alleles is shown in S13C–S13F Fig. (H) Expression analysis of ECT1 mRNA in wild type and T-DNA insertion lines by qPCR. *PS9 Dataset). Northern blot using the probe (P) marked in G detects ECT1-TFP mRNA, but the endogenous ECT1 transcript is below detection limit (S13B Fig). (I) Morphological appearance of seedlings with or without ECT1 in the different backgrounds indicated. Nomenclature and additional phenotyping of these and alternative allele combinations can be found in S14 Fig. DAG, days after germination. Scale bars are: 1 cm in A, 1 mm in B, 100 μm in C, 10 μm in D-F, 1 mm in upper panels of I, and 1 cm in the lower panels.