Homozygous atnup62 mutant seedlings harbouring the DR5::GUS construct, compared to isogenic DR5::GUS seedlings, displayed a higher GUS activity in cotyledons, in which the staining extended towards the centre of these organs (Fig. 3d, left).
Conversely, deletions to position -472 and -366 resulted in a two-fold decrease in GUS expression compared to the -1,307:: GUS line, while deletion to position -262 resulted in a five-fold decrease.
Interestingly, control roots (− NaCl) showed stronger GUS signal compared to those treated with 150 mM NaCl.
Throughout leaf tissue, promoters from both hyperaccumulator species drove enhanced GUS activity compared to AtHMA4p, which is consistent with a possible role in increasing Zn accumulation in leaf epidermal cells in N. caerulescens [46], [47] and mesophyll cells in A. halleri [48].
There were no significant increases in GUS activity compared to the untreated seedlings for any of the treatments (Table 1).
However, in our hands the expression is most evident in this region of the root [ 36]. spt-11 has a broader expression domain of both PIN4 and DR5::GUS when compared to wild type, suggesting a broader auxin maximum or an increase in auxin sensitivity, which might contribute to a larger QC and RAM in these plants.
In these assays, all three substitutions displayed >50% reductions in the levels of GUS activity when compared to the unmodified binding element 2X-GUS construct.
Moreover, the FT promoter showed increased activity both in LD and SD in the atjmj4-1 homutantss mutants when the construct containing the FT promoter fused with β-glucuronidase (FT::GUS) [14] was compared to expression levels in wt Col (Figure 2E).
The 35S promoter drove the highest GUS expression level compared to the maximum expression level of each transgenic construct.
The D2-527 promotransgenicenic plants consistently showed lowest GUS activity as compared to full-length and D3-436 truncated-promoter transgenic plants in all the tissues.
