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<p>The morphophysiological, biochemical and molecular-genetic mechanisms of resistance of <i>Amaranthus retroflexus</i> (C<sub>4</sub>-NAD-ME) to moderate exposure to the following factors: drought (φ =  − 0.3&#xa0;MPa) and elevated temperature (eT, 35 ± 2&#xa0;°C) at ambient (400&#xa0;ppm) and elevated CO<sub>2</sub> concentrations (eCO<sub>2</sub>, 800&#xa0;ppm), were studied. The parameters of growth, water–salt metabolism, osmotic and oxidative imbalance, CO<sub>2</sub>/H<sub>2</sub>O gas exchange, the PSI and II efficiency, the expression of genes encoding components of electron transport chain (<i>psaA, B, psbA, PGR5, PnsB5, FDI, FDII, FNR1</i>) and dark CO<sub>2</sub> fixation (<i>rbcL, RbcS, Ppc1, 2, PPDK</i>), and the concentration of the key carboxylation enzymes ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC) were measured. <i>Amaranthus retroflexus</i> demonstrated drought and heat tolerance mediated by a complex adaptive response involving both the light and dark stages of photosynthesis and an antioxidant complex. Our findings indicate a specific response of <i>A. retroflexus</i> to all studied factors, except drought: increased expression of the <i>PnsB5</i> gene, associated with NDH-dependent cyclic electron transport (CET) pathway of PSI, which supplies additional ATP for C<sub>4</sub>-NAD carbon concentrating mechanism (CCM). The greatest negative impact, leading to reduced growth, was caused by the combined effect of elevated temperature and drought, as well as the simultaneous presence of all three factors. Under these conditions, upregulation of genes in both CET PSI pathways was observed. The synergistic effect, namely an increase in growth (37%) and shoot water content (72%), was observed only under the combined action of eCO<sub>2</sub> + eT. The slightly moderating effect of eCO<sub>2</sub> was found under eT and combined eT and drought conditions. Analysis of the adaptive responses of <i>A. retroflexus</i> to individual and combined effects of factors provides valuable information for developing adaptation strategies for promising crops. This also may aid in predicting species-specific adaptive responses and their impact on carbon fluxes in leaves under global climate change.</p>

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Climatic factors influence cyclic electron transport of PSI in Amaranthus retroflexus (C4-NAD-ME)

  • 期刊论文

  • 发表日期：

    2026年5月13日

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  • Zulfira Rakhmankulova,
  • Elena Shuyskaya,
  • Maria Prokofieva,
  • Luizat Saidova,
  • Nina Lunkova,
  • Pavel Voronin

摘要

The morphophysiological, biochemical and molecular-genetic mechanisms of resistance of Amaranthus retroflexus (C4-NAD-ME) to moderate exposure to the following factors: drought (φ =  − 0.3 MPa) and elevated temperature (eT, 35 ± 2 °C) at ambient (400 ppm) and elevated CO2 concentrations (eCO2, 800 ppm), were studied. The parameters of growth, water–salt metabolism, osmotic and oxidative imbalance, CO2/H2O gas exchange, the PSI and II efficiency, the expression of genes encoding components of electron transport chain (psaA, B, psbA, PGR5, PnsB5, FDI, FDII, FNR1) and dark CO2 fixation (rbcL, RbcS, Ppc1, 2, PPDK), and the concentration of the key carboxylation enzymes ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC) were measured. Amaranthus retroflexus demonstrated drought and heat tolerance mediated by a complex adaptive response involving both the light and dark stages of photosynthesis and an antioxidant complex. Our findings indicate a specific response of A. retroflexus to all studied factors, except drought: increased expression of the PnsB5 gene, associated with NDH-dependent cyclic electron transport (CET) pathway of PSI, which supplies additional ATP for C4-NAD carbon concentrating mechanism (CCM). The greatest negative impact, leading to reduced growth, was caused by the combined effect of elevated temperature and drought, as well as the simultaneous presence of all three factors. Under these conditions, upregulation of genes in both CET PSI pathways was observed. The synergistic effect, namely an increase in growth (37%) and shoot water content (72%), was observed only under the combined action of eCO2 + eT. The slightly moderating effect of eCO2 was found under eT and combined eT and drought conditions. Analysis of the adaptive responses of A. retroflexus to individual and combined effects of factors provides valuable information for developing adaptation strategies for promising crops. This also may aid in predicting species-specific adaptive responses and their impact on carbon fluxes in leaves under global climate change.