近日，美国加州大学伯克利分校Stolper, Daniel A.团队研究了末次冰期光呼吸作用增强的同位素证据。这一研究成果发表在2025年11月5日出版的《自然—地球科学》杂志上。
低大气二氧化碳水平被认为抑制陆地植物的生产力，部分原因是促进了光呼吸，其中C3植物吸收分子氧并释放二氧化碳。这可以作为一种负反馈，限制冰川时期大气中二氧化碳的下降。然而，较冷的冰川温度会抑制光呼吸，可能会抵消这种反馈。
研究组通过将基于木材甲氧基团块同位素组成的光呼吸速率替代方法（在现代和近代树木中得到验证）应用于最后一个冰期的北美亚化石树木标本，来验证陆地植物在冰期进行更多光呼吸的假设。研究组发现，在无冰的北美大部分地区，末次冰期的树木比来自相似地点的近代树木和来自高纬度地区的当代树木光呼吸更多。
研究组将这些差异调和为温度、大气二氧化碳水平和光呼吸之间的单一模型关系，这表明，在冰期，光呼吸主要在较温暖的生长环境中增加，温度下降了约6°C或以下。这支持了负反馈的假设，即在冰期通过增加光呼吸和限制陆地植物生产力来调节大气中的二氧化碳。
附：英文原文
Title: Isotopic evidence for elevated photorespiration during the last glacial period
Author: Lloyd, Max K., Sprengel, Rebekah S., Wortham, Barbara E., Dunn, Regan E., Ibarra, Daniel E., Dawson, Todd E., Stolper, Daniel A.
Issue&Volume: 2025-11-05
Abstract: Low atmospheric carbon dioxide levels are thought to suppress land plant productivity in part by promoting photorespiration, wherein illuminated C3 plants uptake molecular oxygen and release carbon dioxide. This could act as a negative feedback that limits atmospheric carbon dioxide decline during glacial periods. However, colder glacial temperatures would suppress photorespiration, potentially counteracting this feedback. Here we tested the hypothesis that land plants photorespired more during glacial periods by applying a proxy for photorespiration rate based on clumped isotope compositions of wood methoxyl groups, validated in modern and recent trees, to North American subfossil tree specimens from the last glacial period. We find that, across most of ice-free North America, trees from the last glacial period photorespired more than more recent trees from similar locations and more than contemporary trees from higher latitudes. We reconcile these differences using a single model relationship between temperature, atmospheric carbon dioxide levels and photorespiration, which suggests that, during glacial periods, photorespiration increased primarily in warmer growing environments that cooled by about 6°C or less. This supports the hypothesis of a negative feedback that regulates atmospheric carbon dioxide by increasing photorespiration and restricting land plant productivity during glacial periods.
DOI: 10.1038/s41561-025-01841-x
Source: https://www.nature.com/articles/s41561-025-01841-x