Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan.
Sci Rep. 2024 May 29;14(1):12311. doi: 10.1038/s41598-024-62975-3.
The leaves of many trees emit volatile organic compounds (abbreviated as BVOCs), which protect them from various damages, such as herbivory, pathogens, and heat stress. For example, isoprene is highly volatile and is known to enhance the resistance to heat stress. In this study, we analyze the optimal seasonal schedule for producing isoprene in leaves to mitigate damage. We assume that photosynthetic rate, heat stress, and the stress-suppressing effect of isoprene may vary throughout the season. We seek the seasonal schedule of isoprene production that maximizes the total net photosynthesis using Pontryagin's maximum principle. The isoprene production rate is determined by the changing balance between the cost and benefit of enhanced leaf protection over time. If heat stress peaks in midsummer, isoprene production can reach its highest levels during the summer. However, if a large portion of leaves is lost due to heat stress in a short period, the optimal schedule involves peaking isoprene production after the peak of heat stress. Both high photosynthetic rate and high isoprene volatility in midsummer make the peak of isoprene production in spring. These results can be clearly understood by distinguishing immediate impacts and the impacts of future expectations.
许多树木的叶子会释放挥发性有机化合物（简称 BVOCs），这些化合物可以保护树木免受各种损害，如草食性动物、病原体和热应激。例如，异戊二烯具有很强的挥发性，已知可以增强对热应激的抵抗力。在本研究中，我们分析了叶子中产生异戊二烯的最佳季节时间表，以减轻损害。我们假设光合作用率、热应激以及异戊二烯的应激抑制作用可能会随季节而变化。我们使用庞特里亚金极大值原理寻求最大总净光合作用的异戊二烯生产的季节性时间表。异戊二烯的生产速率取决于随着时间的推移，增强叶片保护的成本和收益之间不断变化的平衡。如果热应激在仲夏达到峰值，那么异戊二烯的生产可以在夏季达到最高水平。然而，如果大量叶子在短时间内因热应激而丧失，那么最佳时间表涉及在热应激峰值之后达到异戊二烯生产的峰值。仲夏时高光合作用率和高异戊二烯挥发性使得春季的异戊二烯生产达到峰值。通过区分即时影响和未来预期的影响，可以清楚地理解这些结果。
