<i>NtAQP1</i> complements growth inhibition of <i>AtHXK1</i>.

<p>(A) Representative images of 5-week-old tomato plants homozygous for <i>NtAQP1</i> (AQP1), <i>AtHXK1</i> (HK4) or both genes (AQP1xHK4). (B) Height (<i>n</i>≥8) and (C) leaf area (<i>n</i>≥6) of 9-week-old plants. (D) Hexokinase activity was determined using protein extracted from mature leaves of WT, AQP1, HK4 and AQP1xHK4 plants. Data are means of five independent biological repeats ± SE. (E) Relative expression of <i>SlCAB1</i> (<i>Solanum lycopersicum</i> a/b binding protein) in WT, AQP1, HK4 and AQP1xHK4 plants. Data are means of five-six independent biological repeats ± SE. (B–E) Different letters indicate a significant difference (<i>t</i> test, <i>P</i><0.05).</p

Plant growth is affected by <i>NtAQP1</i> and <i>AtHXK1</i> gene dosage.

<p>Height of transgenic plants with one copy (hemizygous, +/−) or two copies (homozygous, +/+) of <i>AtHXK1</i> and <i>NtAQP1</i>. The zygosity state of each gene is specified on the x-axis. −/− indicates the absence of the specified gene, −/+ indicates hemizygosity and +/+ indicates homozygosity. Three left columns: no <i>NtAQP1</i>; middle three columns: hemizygous for <i>NtAQP1</i>; three right columns: homozygous for <i>NtAQP1</i>. Data are means of at least six independent repeats ± SE. Different letters indicate a significant difference (<i>t</i> test, <i>P</i><0.05).</p

Reciprocal grafting and whole-plant relative daily transpiration.

<p>Reciprocal grafting of WT, AQP1 and HK4 plants was performed at the seedling stage. The plants were photographed (A and Fig. 2A in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087888#pone.0087888-Kelly2" target="_blank">[30]</a>) and their transpiration was measured about 4 weeks after grafting. (B) Whole-plant relative daily transpiration of reciprocal-grafted plants. Data were normalized to the total plant weight and the amount of water taken up by the neighboring submerged fixed-size wick each day, which was set to 100%. Presented data are means of four independent repeats ± SE. Different letters indicate a significant difference (<i>t</i> test, <i>P</i><0.05).</p

Transpiration rate of AQP1xHK4 plants.

<p>The rate of transpiration was monitored continuously throughout the day for each line (AQP1, HK4, AQP1xHK4 and WT). The presented data are the means ± SE for each 10^th sampling point (<i>n</i> = 6). The transpiration data were normalized to the total leaf area and the amount taken up by the neighboring submerged fixed-size wick each day, which was set to 100%.</p

Photosynthetic and hydraulic characteristics of WT, AQP1, AQP1xHK4 and HK4 plants.

<p><i>L</i>_r, root hydraulic conductance; <i>K</i>_sx, xylem-specific stem hydraulic conductivity; <i>A</i>_N, net photosynthesis; <i>g</i>_s, stomatal conductance; <i>g</i>_m, mesophyll CO₂ conductance; <i>C</i>_i, substomatal CO₂ concentration; C_c, Chloroplast CO₂ concentration; <i>J</i>, the rate of electron transport. Presented data are means ± SE (<i>n</i>, number of replicates, as indicated in parentheses). Different letters in a row indicate significant differences (<i>t</i> test, <i>P</i><0.05).</p

<i>AtHXK1</i> decreases root hydraulic conductance and stem hydraulic conductivity.

<p>Root conductance (A) and xylem-specific stem hydraulic conductivity (B) were determined for control (WT) and transgenic plants expressing different levels of <i>AtHXK1</i> (<i>AtHXK1</i> expression from moderate to high: HK37[25]). Data are means ± SE (<i>n</i>≥6 for <i>L</i>_r; <i>n</i>≥5 for <i>K</i>_sx). Different letters indicate a significant difference (<i>t</i> test, <i>P</i><0.05).</p