L 1 hygromycin b

A 1465 bp region harboring XND1 5′-UTR and coding sequence, without stop codon and in its wild-type or SNP_UTR-mutated Bur-0 form, was amplified from above mentioned XND1-pGreen0179 clones. The fragment was cloned using the Gateway Technology (Invitrogen), downstream of a 35SCaMV promoter and in fusion with GFP in a pGWB505 vector^{51 (link)}. The primers used are listed in Supplementary Table 2. The constructs were confirmed by sequencing and transferred into xnd1–5 mutant plants. For each construct, nine to ten independent transgenic lines were selected in T2 generation on 30 mg L⁻¹ hygromycin B (Sigma), cultured in hydoponics and checked for XND1-GFP transcript abundance and GFP fluorescence intensity in roots. The primers used for qRT-PCR are listed in Supplementary Table 2. For quantification of the GFP fluorescence intensity, roots of 21- to 23-day-old plants were observed using a fluorescence microscope (Zeiss Axio Observer 7) and mean gray values in 400 µm root tips were quantified using an ImageJ program (NIH, USA). Data were normalized to the corresponding value of the line C9-3, which possessed the lowest transcript abundance and fluorescence intensity.