Yudina Lyubov, Popova Alyona, Zolin Yuriy, Sukhova Ekaterina, Sukhov Vladimir
Department of Biophysics, N.I. Lobachevsky State University of Nizhny Novgorod, 603022 Nizhny Novgorod, Russia.
Plants (Basel). 2023 Jul 7;12(13):2570. doi: 10.3390/plants12132570.
Long-distance electrical signals caused by the local action of stressors influence numerous physiological processes in plants including photosynthesis and increase their tolerance to the action of adverse factors. Depolarization electrical signals were mainly investigated; however, we earlier showed that hyperpolarization electrical signals (HESs) can be caused by moderate stressors (e.g., local moderate heating) and induce photosynthetic inactivation. We hypothesized that HESs are related to stressor-induced increases in the hydrostatic pressure in the zone of action of the stressor and following the propagation of a hydraulic wave. In the current work, we tested this hypothesis through the direct investigation of electrical signals induced by the local action of artificially increased pressure and an analysis of the subsequent photosynthetic changes in the nonirritated parts of plants. The electrical signals and parameters of photosynthetic light reactions were investigated in wheat plants. The local action of the increased pressure was induced by the action of weights on the wheat leaf. Extracellular electrodes were used for electrical signal measurements. Pulse-amplitude-modulation fluorescent imaging was used for measurements of the quantum yield of photosystem II and nonphotochemical quenching of chlorophyll fluorescence in wheat leaves. It was shown that the local action of pressure on wheat leaf induced electrical signals near the irritated zone: HESs were caused by low pressure (10 kPa) and depolarization signals were induced by high pressure (100 kPa). The local action of moderate pressure (50 kPa) induced weak electrical signals near the irritated zone; however, HESs were observed with increasing distance from this zone. It was also shown that the local action of this moderate pressure induced the photosynthetic inactivation (decreasing the quantum yield of photosystem II and increasing the nonphotochemical quenching of chlorophyll fluorescence) in the nonirritated parts of the wheat leaves. Thus, our results show that the local action of the increased pressure and, probably, subsequent propagation of the hydraulic wave induce electrical signals (including HESs) and photosynthetic inactivation in nonirritated parts of plants that are similar to ones caused by the local action of moderate stressors (e.g., moderate heating). This means that both HESs and depolarization electrical signals can have a hydraulic mechanism of propagation.
由应激源的局部作用引起的长距离电信号会影响植物体内的众多生理过程，包括光合作用，并提高植物对不利因素作用的耐受性。过去主要研究的是去极化电信号；然而，我们之前的研究表明，超极化电信号（HESs）可由适度的应激源（如局部适度加热）引发，并导致光合作用失活。我们推测，HESs与应激源作用区域内静水压力的增加以及随后液压波的传播有关。在当前的研究中，我们通过直接研究人工增加压力的局部作用所引发的电信号，并分析植物未受刺激部分随后的光合变化，来验证这一假设。我们对小麦植株的电信号和光合光反应参数进行了研究。通过在小麦叶片上施加重物来诱导压力增加的局部作用。使用细胞外电极测量电信号。采用脉冲幅度调制荧光成像技术测量小麦叶片中光系统II的量子产率和叶绿素荧光的非光化学猝灭。结果表明，对小麦叶片施加压力的局部作用会在受刺激区域附近诱发电信号：低压（10千帕）会引发HESs，高压（100千帕）会诱发去极化信号。中等压力（50千帕）的局部作用会在受刺激区域附近诱发微弱的电信号；然而，随着与该区域距离的增加，会观察到HESs。研究还表明，这种中等压力的局部作用会导致小麦叶片未受刺激部分的光合作用失活（光系统II的量子产率降低，叶绿素荧光的非光化学猝灭增加）。因此，我们的研究结果表明，压力增加的局部作用以及随后可能的液压波传播会在植物未受刺激部分诱发电信号（包括HESs）和光合作用失活，这与适度应激源（如适度加热）的局部作用所引发的情况相似。这意味着HESs和去极化电信号都可能具有液压传播机制。
