Fig. 4
Effects of low N condition on the expression of root nitrate transporter genes (a-d), H+ efflux (e), NO3− influx (f), dry weight (DW) (g-h) and root/shoot ratio (i) in a newly formed hexaploid (neo-6×), its diploid (2×) and tetraploid (4×) parents, and natural allohexaploid (nat-6×). (a-d) The fold increase of the gene expression was calculated according to (treatment-control) /control, and the percentage of gene expression decrease was calculated according to (control-treatment)*100% /control. (e-i) Asterisks indicated significant difference (t test, P < 0.05) between control and low N-stressed plants for a given genotype. The means of any two of all four lines at the same N condition were compared using t test (P < 0.05), and means followed by different letters at the same N condition are significant. The values are means of 3–7 biological replicates. When the seedlings were subjected to low N condition (0.1 mM) for 7 days, gene expression, NO3− influx and H+ efflux were measured. The dry weights of the roots and shoots were measured and root DW /shoot DW ratio (root /shoot ratio) was calculated at 31 days of the stress. Under 5 mM N condition, we did not detect any NO3− flux signal due to high background signal of NO3−, thus, NO3− influx data of only 0.1 mM N treatment was displayed in the Figure f