Department of Biology, University of Padova, Via Ugo Bassi 58B, 35121, Padua, Italy.
Botanical Garden, University of Padova, 35123, Padua, Italy.
Planta. 2019 Apr;249(4):1217-1228. doi: 10.1007/s00425-018-03077-z. Epub 2019 Jan 3.
Investigation of photosynthesis regulation in different plant groups exposed to variable conditions showed that all species have similar photosynthetic electron transport modulation while excess energy dissipation is species specific. Photosynthesis is regulated in response to dynamic environmental conditions to satisfy plant metabolic demands while also avoiding possible over-excitation of the electron transport chain and the generation of harmful reactive oxygen species. Photosynthetic organisms evolved several mechanisms to modulate light harvesting and electron transport efficiency to respond to conditions changing at different timescales, going from fast sun flecks to slow seasonal variations. These regulatory mechanisms changed during evolution of photosynthetic organisms, also adapting to various ecological niches, making the investigation of plant biodiversity highly valuable to uncover conserved traits and plasticity of photosynthetic regulation and complement studies on model species. In this work, a set of plants belonging to different genera of angiosperms, gymnosperms, ferns and lycophytes were investigated by monitoring their photosynthetic parameters in different seasons looking for common trends and differences. In all plants, analysed photosynthetic electron transport rate was found to be modulated by growth light intensity, ensuring a balance between available energy and photochemical capacity. Growth light also influenced the threshold where heat dissipation of excitation energy, a mechanism called non-photochemical quenching (NPQ), was activated. On the contrary, NPQ amplitude did not correlate with light intensity experienced by the plants but was a species-specific feature. The zeaxanthin-dependent component of NPQ, qZ, was found to be the most variable in different plants and its modulation influenced the intensity and the kinetic properties of the response.
对不同植物群体在可变条件下的光合作用调节的研究表明，所有物种在光合作用电子传递调节方面都具有相似性，而过剩的能量耗散则是物种特异性的。光合作用会根据动态环境条件进行调节，以满足植物代谢需求，同时避免电子传递链的过度激发和有害活性氧物质的产生。光合生物进化出了几种调节机制来调节光捕获和电子传递效率，以响应不同时间尺度的变化，从快速的光斑到缓慢的季节性变化。这些调节机制在光合生物的进化过程中发生了变化，也适应了各种生态位，因此对植物生物多样性的研究具有很高的价值，可以揭示光合作用调节的保守特征和可塑性，并补充对模式物种的研究。在这项工作中，通过监测不同季节的光合作用参数，研究了一组属于被子植物、裸子植物、蕨类植物和石松类植物不同属的植物，寻找共同的趋势和差异。在所有植物中，分析发现光合作用电子传递速率受到生长光强的调节，以确保可用能量和光化学容量之间的平衡。生长光还影响激发能热耗散（非光化学猝灭，NPQ）机制被激活的阈值。相反，NPQ 幅度与植物经历的光强度无关，而是物种特异性的特征。NPQ 的叶黄素依赖性成分 qZ 在不同植物中变化最大，其调节会影响响应的强度和动力学特性。
