Yan Hui, Fu Kai, Li Jiajia, Li Mingyong, Li Shaofan, Dai Zhiguang, Jin Xin
College of Agricultural Equipment Engineering, Henan University of Science and Technology, Luoyang 471000, China.
Plants (Basel). 2024 Sep 17;13(18):2594. doi: 10.3390/plants13182594.
To understand the physiological responses of seedlings to mechanical wounding, we analyzed photosynthesis, chlorophyll fluorescence, and endogenous hormones in tomato ( L.) subjected to varying levels of mechanical pressure. The results showed that, at 4 h after wounding, excess excitation energy was dissipated as thermal energy through the reduction in the photosystem II (PSII) opening degree and the increase in non-photochemical quenching. Photodamage was avoided, and stomatal closure was the most prominent factor in photosynthesis inhibition. However, 12 h after wounding, the photoprotective mechanism was insufficient to mitigate the excess excitation energy caused by the wound, leading to photochemical damage to physiological processes. Meanwhile, the non-stomatal factor became the most prominent limiting factor for photosynthesis at 80 N pressure. At 12 and 36 h after wounding, the concentrations of abscisic acid (ABA), methyl jasmonate (MeJA), indole-3-acetic acid (IAA), zeatin riboside (ZR), and gibberellic acid (GA) in the stems showed a trend towards being increased, which promoted wound healing. However, after mechanical wounding, the ratio of stress- to growth-promoting hormones first increased and then decreased. This pattern can enhance stress resistance and promote cell division, respectively. Comprehensive analysis showed that the fluorescence parameter, photochemical quenching coefficient (_Lss), was the most suitable indicator for evaluating mechanical wounding conditions.
为了解幼苗对机械损伤的生理响应，我们分析了遭受不同程度机械压力的番茄（L.）的光合作用、叶绿素荧光和内源激素。结果表明，在受伤后4小时，过剩的激发能通过光系统II（PSII）开放度的降低和非光化学猝灭的增加以热能的形式耗散。避免了光损伤，气孔关闭是光合作用抑制中最突出的因素。然而，在受伤后12小时，光保护机制不足以减轻伤口引起的过剩激发能，导致对生理过程的光化学损伤。同时，在80 N压力下，非气孔因素成为光合作用最突出的限制因素。在受伤后12小时和36小时，茎中脱落酸（ABA）、茉莉酸甲酯（MeJA）、吲哚-3-乙酸（IAA）、玉米素核苷（ZR）和赤霉素（GA）的浓度呈现增加趋势，这促进了伤口愈合。然而，机械损伤后，促胁迫激素与促生长激素的比值先增加后降低。这种模式可分别增强抗逆性和促进细胞分裂。综合分析表明，荧光参数光化学猝灭系数（_Lss）是评估机械损伤条件的最合适指标。
