Loreto Francesco, Fineschi Silvia
Department of Biology, Agriculture and Food Sciences, The National Research Council of Italy (CNR), P. le Aldo Moro 7, Roma, 00185, Italy.
New Phytol. 2015 Apr;206(2):578-82. doi: 10.1111/nph.13242. Epub 2014 Dec 31.
Compilation and analysis of existing inventories reveal that isoprene is emitted by c. 20% of the perennial vegetation of tropical and temperate regions of the world. Isoprene emitters are found across different plant families without any clear phylogenetic thread. However, by critically appraising information in inventories, several ecological patterns of isoprene emission can be highlighted, including absence of emission from C4 and annual plants, and widespread emission from perennial and deciduous plants of temperate environments. Based on this analysis, and on available information on biochemistry, ecology and functional roles of isoprene, it is suggested that isoprene may not have evolved to help plants face heavy or prolonged stresses, but rather assists C3 plants to run efficient photosynthesis and to overcome transient and mild stresses, especially during periods of active plant growth in warm seasons. When the stress status persists, or when evergreen leaves cope with multiple and repeated stresses, isoprene biosynthesis is replaced by the synthesis of less volatile secondary compounds, in part produced by the same biochemical pathway, thus indicating causal determinism in the evolution of isoprene-emitting plants in response to the environment.
对现有排放清单的汇编与分析表明，异戊二烯由世界热带和温带地区约20%的多年生植被排放。在不同植物科中均发现了异戊二烯排放植物，且不存在明显的系统发育线索。然而，通过严格评估排放清单中的信息，可以突出异戊二烯排放的几种生态模式，包括C4植物和一年生植物不排放异戊二烯，以及温带环境中的多年生和落叶植物广泛排放异戊二烯。基于这一分析以及关于异戊二烯的生物化学、生态学和功能作用的现有信息，有人提出，异戊二烯的进化可能并非为了帮助植物应对严重或长期胁迫，而是协助C3植物进行高效光合作用并克服短暂和轻度胁迫，尤其是在温暖季节植物活跃生长期间。当胁迫状态持续存在，或者常绿树叶应对多种反复胁迫时，异戊二烯生物合成会被挥发性较低的次生化合物合成所取代，部分次生化合物由相同的生化途径产生，这表明异戊二烯排放植物在进化过程中对环境的响应存在因果决定论。
