Photos of stomata.

<p>Stomata of A) diploid and B) tetraploid individual of <i>K</i>. <i>arvensis</i>.</p

Summary of differences between cytotypes, treatments and traits.

<p>Differences between diploid (2x) and tetraploid (4x) plants growing in different treatments (shade, drought and control) in A) values of the effective quantum yield of photosystem II photochemistry in light-adapted leaves (Qy) of, B) performance index for energy conservation from Photosystem II antenna to the reduction of Q_B (PI_ABS) measured in dark-adapted leaves, C) performance index for energy conservation from Photosystem II antenna to the reduction of Photosystem I end electron acceptors (PI_TOTAL) measured in dark-adapted leaves, D) chlorophyll a content, E) specific leaf mass (SLM), F) cumulative number of flowering stalks and G) cumulative number of flower heads. The graphs show means and standard errors of the mean (SE). Columns sharing the same letter are not significantly different (P > 0.05).</p

Summary of the effects of ploidy level and treatment on the different traits.

<p>The effect of ploidy level, treatment and their interaction on effective quantum yield of photosystem II photochemistry in light-adapted leaves (Qy), performance index for energy conservation from Photosystem II antenna to the reduction of Photosystem I end electron acceptors (PI_TOTAL)_, performance index for energy conservation from Photosystem II antenna to the reduction of Q_B (PI_ABS)_, content of chlorophylls a and b and total carotenoids, specific leaf mass (SLM), cumulative number of flower heads and flowering stalks over 2012 and 2013 and plant height in 2013 measured in diploid and tetraploid plants growing in different treatments (shade, drought and control). Significant values (P < 0.05) are shown in bold. 2x or 4x next to ploidy level indicates that diploids (2x) have significantly higher values of the respective parameter than tetraploids and the other way round. Letters next to treatment indicate which plants (C-control, S-shaded, D-drought-stressed) have significantly higher values of the respective parameter. Effect of population is only shown in S6 Table. Results marked by * are significant even after sequential Bonferroni correction.</p

Map of the populations.

<p>Locations of the diploid (crosses) and tetraploid (circles) study populations in the Czech Republic, Europe.</p

Contents of total and individual brassinosteroids (BRs) in two maize genotypes (2023 and CE704).

<p>Plants were either subjected to normal watering (control; grey columns) or to 14 days of withholding water (stress; black columns). Mean values ± SEM are shown (n = 3). Asterisks indicate significant (<i>p</i>≤0.05; *) or highly significant (<i>p</i>≤0.01; **) differences between mean values according to Tukey's tests made separately for each genotype (in case of the differences between control and stress treatment) or for each treatment (in case of the differences between both genotypes). BL … brassinolide, CS … castasterone, DS … dolichosterone, FM … leaf fresh mass, TY … typhasterol.</p

The contents of proline, H₂O₂, malondialdehyde (MDA), the antioxidant activities and the index of membrane injury in two maize genotypes (2023 and CE704).

<p>Plants were either subjected to normal watering (control; grey columns) or to 14 days of withholding water (stress; black columns). Mean values ± SEM are shown (n = 6 for the contents of MDA, n = 4 for the other parameters). Asterisks indicate significant (<i>p</i>≤0.05; *) or highly significant (<i>p</i>≤0.01; **) differences between mean values according to Tukey's tests made separately for each genotype (in case of the differences between control and stress treatment) or for each treatment (in case of the differences between both genotypes).AsA … ascorbate, APX … ascorbate peroxidase, CAT … catalase, FM … leaf fresh mass.</p

Drought-tolerant and drought-sensitive genotypes of maize (<i>Zea mays</i> L.) differ in contents of endogenous brassinosteroids and their drought-induced changes

<div><p>The contents of endogenous brassinosteroids (BRs) together with various aspects of plant morphology, water management, photosynthesis and protection against cell damage were assessed in two maize genotypes that differed in their drought sensitivity. The presence of 28-norbrassinolide in rather high quantities (1–2 pg mg^-1 fresh mass) in the leaves of monocot plants is reported for the first time. The intraspecific variability in the presence/content of the individual BRs in drought-stressed plants is also described for the first time. The drought-resistant genotype was characterised by a significantly higher content of total endogenous BRs (particularly typhasterol and 28-norbrassinolide) compared with the drought-sensitive genotype. On the other hand, the drought-sensitive genotype showed higher levels of 28-norcastasterone. Both genotypes also differed in the drought-induced reduction/elevation of the levels of 28-norbrassinolide, 28-norcastasterone, 28-homocastasterone and 28-homodolichosterone. The differences observed between both genotypes in the endogenous BR content are probably correlated with their different degrees of drought sensitivity, which was demonstrated at various levels of plant morphology, physiology and biochemistry.</p></div

Selected parameters of plant morphology in two maize genotypes (2023 and CE704).

<p>Plants were either subjected to normal watering (control; grey columns) or to 14 days of withholding water (stress; black columns). Mean values ± SEM are shown (n = 8). Asterisks indicate significant (<i>p</i>≤0.05; *) or highly significant (<i>p</i>≤0.01; **) differences between mean values according to Tukey's tests made separately for each genotype (in case of the differences between control and stress treatment) or for each treatment (in case of the differences between both genotypes).</p

The difference kinetics and the relative variable fluorescences calculated from OJIP analysis of two maize genotypes (2023 and CE704).

<p>The difference kinetics ΔW_OJ (<b>A</b>) reveals the K-band; ΔW_OK (<b>B</b>) reveals the L-band. Only the part between the I and P points of the OJIP curve is shown for the relative variable fluorescence W_OI (<b>C</b>). The normalization of OJIP curve between the I and P points with the maximum amplitude fixed as 1 is shown as the relative variable fluorescence W_IP (<b>D</b>). Plants were subjected either to normal watering (control) or to 14 days of withholding water (stress). ΔW_OJ and ΔW_OK were calculated from the comparisons of the stressed and control plants; the latter are represented by the zero point of the respective y axes in graphs <b>A</b> and <b>B</b>. Mean values (n = 8) are shown. r.u. … relative units.</p

Selected parameters of gas exchange, the osmotic potential and the contents of chlorophylls and carotenoids in leaves of two maize genotypes (2023 and CE704).

<p>Plants were either subjected to normal watering (control; grey columns) or to 14 days of withholding water (stress; black columns). Mean values ± SEM are shown (n = 8 for gas exchange and the contents of photosynthetic pigments, n = 12 for osmotic potential). Asterisks indicate significant (<i>p</i>≤0.05; *) or highly significant (<i>p</i>≤0.01; **) differences between mean values according to Tukey's tests made separately for each genotype (in case of the differences between control and stress treatment) or for each treatment (in case of the differences between both genotypes).</p