Photosynthesis, Chlorophyll Fluorescence, and Hormone Regulation in Tomato Exposed to Mechanical Wounding

• Published in: Plants (Basel) Vol. 13; no. 18; p. 2594
• Main Authors: Yan, Hui, Fu, Kai, Li, Jiajia, Li, Mingyong, Li, Shaofan, Dai, Zhiguang, Jin, Xin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.09.2024; MDPI
• Subjects: Abscisic acid; Acetic acid; Cell division; Chlorophyll; Dissipation factor; Efficiency; Excitation; Fluorescence; Gibberellic acid; hormonal crosstalk; Hormones; Indoleacetic acid; Mechanical properties; mechanical wounding; Methyl jasmonate; Pattern analysis; Photochemicals; Photosynthesis; photosynthetic limiting factors; Photosystem II; Physiological effects; Physiological responses; Physiology; Plant growth; principle component analysis; PSII efficiency; Quenching; Seedlings; Signal transduction; Stomata; Thermal energy; Tomatoes; Wound healing; Zeatin; Zeatin riboside; United States > US; PSII efficiency; mechanical wounding; photosynthetic limiting factors; hormonal crosstalk; principle component analysis
• ISSN: 2223-7747; 2223-7747
• 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.