植物通常需要承受多种类型的环境压力(例如,盐和低温胁迫),因为它们的固着性质。尽管植物对单一应激源的生理反应已得到充分表征,很少有研究评估了用非致死应激源预处理可以在不利环境中保持植物光合性能的程度(即,驯化诱导的交叉耐受性)。这里,通过测定光合参数和叶绿素荧光参数,研究了氯化钠(NaCl)预处理对低温胁迫下番茄植株光合性能的影响,气孔孔径,叶绿体质量,和应激信号通路相关基因的表达。NaCl预处理显著降低了二氧化碳的同化率,蒸腾速率,和番茄叶的气孔孔径,但是与未预处理的番茄植物相比,这些生理适应可以减轻随后低温的不利影响。低温胁迫下,光合色素含量下降,叶绿体超微结构受到破坏,NaCl预处理减轻了这些不良反应的严重程度。光系统I(PSI)和光系统II(PSII)的量子产率,调节能量耗散的量子产率,NaCl处理后,由于供体侧限制而导致的非光化学能量耗散减少;然而,当NaCl预处理的植物暴露于低温胁迫时,观察到相反的模式。对于PSI的电子转移速率,获得了类似的结果。PSII的电子转移速率,和估计的循环电子流值(CEF)。NaCl预处理也显著缓解了低温胁迫诱导的活性氧的产生。影响气孔孔径的离子通道和微管蛋白相关基因的表达,叶绿素合成基因,抗氧化酶相关基因,在低温胁迫下,NaCl预处理的植物中脱落酸(ABA)和低温信号相关基因被上调。我们的研究结果表明,CEF介导的光保护,气孔运动,叶绿体质量的维持,ABA和低温信号通路在维持低温胁迫下NaCl处理的番茄植株的光合能力中起着关键作用。
Plants often need to withstand multiple types of environmental stresses (e.g., salt and low temperature stress) because of their sessile nature. Although the physiological responses of plants to single stressor have been well-characterized, few studies have evaluated the extent to which pretreatment with non-lethal stressors can maintain the photosynthetic performance of plants in adverse environments (i.e., acclimation-induced cross-tolerance). Here, we studied the effects of sodium chloride (NaCl) pretreatment on the photosynthetic performance of tomato plants exposed to low temperature stress by measuring photosynthetic and chlorophyll fluorescence parameters, stomatal aperture, chloroplast quality, and the expression of stress signaling pathway-related genes. NaCl pretreatment significantly reduced the carbon dioxide assimilation rate, transpiration rate, and stomatal aperture of tomato leaves, but these physiological acclimations could mitigate the adverse effects of subsequent low temperatures compared with non-pretreated tomato plants. The content of photosynthetic pigments decreased and the ultra-microstructure of chloroplasts was damaged under low temperature stress, and the magnitude of these adverse effects was alleviated by NaCl pretreatment. The quantum yield of photosystem I (PSI) and photosystem II (PSII), the quantum yield of regulatory energy dissipation, and non-photochemical energy dissipation owing to donor-side limitation decreased following NaCl treatment; however, the opposite patterns were observed when NaCl-pretreated plants were exposed to low temperature stress. Similar results were obtained for the electron transfer rate of PSI, the electron transfer rate of PSII, and the estimated cyclic electron flow value (CEF). The production of reactive oxygen species induced by low temperature stress was also significantly alleviated by NaCl pretreatment. The expression of ion channel and tubulin-related genes affecting stomatal aperture, chlorophyll synthesis genes, antioxidant enzyme-related genes, and abscisic acid (ABA) and low temperature signaling-related genes was up-regulated in NaCl-pretreated plants under low temperature stress. Our findings indicated that CEF-mediated photoprotection, stomatal movement, the maintenance of chloroplast quality, and ABA and low temperature signaling pathways all play key roles in maintaining the photosynthetic capacity of NaCl-treated tomato plants under low temperature stress.