Falcioni Renan, Chicati Marcelo Luiz, de Oliveira Roney Berti, Antunes Werner Camargos, Hasanuzzaman Mirza, Demattê José A M, Nanni Marcos Rafael
Department of Agronomy, State University of Maringá, Av. Colombo, 5790, Maringá 87020-900, PR, Brazil.
Department of Biotechnology, Genetic and Cellular Biology, State University of Maringá, Av. Colombo, 5790, Maringá 87020-900, PR, Brazil.
Plants (Basel). 2024 Jan 29;13(3):395. doi: 10.3390/plants13030395.
Heat stress is an abiotic factor that affects the photosynthetic parameters of plants. In this study, we examined the photosynthetic mechanisms underlying the rapid response of tobacco plants to heat stress in a controlled environment. To evaluate transient heat stress conditions, changes in photochemical, carboxylative, and fluorescence efficiencies were measured using an infrared gas analyser (IRGA Licor 6800) coupled with chlorophyll a fluorescence measurements. Our findings indicated that significant disruptions in the photosynthetic machinery occurred at 45 °C for 6 h following transient heat treatment, as explained by 76.2% in the principal component analysis. The photosynthetic mechanism analysis revealed that the dark respiration rate (Rd and Rd) increased, indicating a reduced potential for carbon fixation during plant growth and development. When the light compensation point (LCP) increased as the light saturation point (LSP) decreased, this indicated potential damage to the photosystem membrane of the thylakoids. Other photosynthetic parameters, such as , , , and ΦCO, also decreased, compromising both photochemical and carboxylative efficiencies in the Calvin-Benson cycle. The energy dissipation mechanism, as indicated by the NPQ, qN, and thermal values, suggested that a photoprotective strategy may have been employed. However, the observed transitory damage was a result of disruption of the electron transport rate (ETR) between the PSII and PSI photosystems, which was initially caused by high temperatures. Our study highlights the impact of rapid temperature changes on plant physiology and the potential acclimatisation mechanisms under rapid heat stress. Future research should focus on exploring the adaptive mechanisms involved in distinguishing mutants to improve crop resilience against environmental stressors.
热胁迫是一种影响植物光合参数的非生物因素。在本研究中，我们在可控环境下研究了烟草植株对热胁迫快速响应的光合机制。为评估短暂热胁迫条件，使用红外气体分析仪（IRGA Licor 6800）结合叶绿素a荧光测量，测定了光化学、羧化和荧光效率的变化。我们的研究结果表明，短暂热处理后，在45°C处理6小时时，光合机制发生了显著破坏，主成分分析解释了其中76.2%的原因。光合机制分析表明，暗呼吸速率（Rd和Rd）增加，这表明植物生长发育过程中碳固定的潜力降低。当光补偿点（LCP）增加而光饱和点（LSP）降低时，这表明类囊体光合膜可能受到了潜在损伤。其他光合参数，如 、 、 和ΦCO也降低，损害了卡尔文-本森循环中的光化学和羧化效率。由NPQ、qN和热值表示的能量耗散机制表明，可能采用了光保护策略。然而，观察到的短暂损伤是PSII和PSI光系统之间电子传递速率（ETR）中断的结果，最初是由高温引起的。我们的研究强调了快速温度变化对植物生理的影响以及快速热胁迫下潜在的适应机制。未来的研究应侧重于探索区分突变体所涉及的适应机制，以提高作物对环境胁迫的恢复力。
