B concentrations in aerial tissues of ngal1 and NGAL1 expression in tissues. B concentrations in different tissues of wild-type (Col-0) and ngal1 mutant alleles grown hydroponically under (A) control-B (+B) and (B) low-B (−B) conditions were quantified with ICP-MS. In each sample, tissues from five to seven individual plants were pooled as one sample replicate, and data are mean of n = 6 sample replicates. Different letters for each tissue indicate significant reductions in ngal1 mutants (Dunnett’s test; P < 0.05). (C) NGAL1 mRNA accumulation was quantified in indicated tissues of Col-0 plants grown hydroponically under low B and control B. Data are mean of n = 6 pooled sample replicates. Relative expression was normalized to root data at +B as 1.0. Asterisks indicate significant increases under low B (Student’s t-test; *, P < 0.05, **, P < 0.01, n.s.—not significant). B concentrations in the treated conditions were as follows: low B (−B: 0.1 µM B) and control B (+B: 30 µM B).