Tattini Massimiliano, Velikova Violeta, Vickers Claudia, Brunetti Cecilia, Di Ferdinando Martina, Trivellini Alice, Fineschi Silvia, Agati Giovanni, Ferrini Francesco, Loreto Francesco
Institute for Plant Protection, Department of Biology, Agriculture and Food Sciences, The National Research Council of Italy (CNR), I-50019, Sesto Fiorentino (Florence), Italy.
Plant Cell Environ. 2014 Aug;37(8):1950-64. doi: 10.1111/pce.12350. Epub 2014 May 22.
Isoprene strengthens thylakoid membranes and scavenges stress-induced oxidative species. The idea that isoprene production might also influence isoprenoid and phenylpropanoid pathways under stress conditions was tested. We used transgenic tobacco to compare physiological and biochemical traits of isoprene-emitting (IE) and non-emitting (NE) plants exposed to severe drought and subsequent re-watering. Photosynthesis was less affected by drought in IE than in NE plants, and higher rates were also observed in IE than in NE plants recovering from drought. Isoprene emission was stimulated by mild drought. Under severe drought, isoprene emission declined, and levels of non-volatile isoprenoids, specifically de-epoxidated xanthophylls and abscisic acid (ABA), were higher in IE than in NE plants. Soluble sugars and phenylpropanoids were also higher in IE plants. After re-watering, IE plants maintained higher levels of metabolites, but isoprene emission was again higher than in unstressed plants. We suggest that isoprene production in transgenic tobacco triggered different responses, depending upon drought severity. Under drought, the observed trade-off between isoprene and non-volatile isoprenoids suggests that in IE plants isoprene acts as a short-term protectant, whereas non-volatile isoprenoids protect against severe, long-term damage. After drought, it is suggested that the capacity to emit isoprene might up-regulate production of non-volatile isoprenoids and phenylpropanoids, which may further protect IE leaves.
异戊二烯可强化类囊体膜并清除应激诱导产生的氧化物质。我们对异戊二烯生成在应激条件下可能也会影响类异戊二烯和苯丙烷类途径这一观点进行了验证。我们使用转基因烟草来比较暴露于严重干旱及随后复水条件下的异戊二烯释放型（IE）和非释放型（NE）植株的生理和生化特性。与NE植株相比，干旱对IE植株光合作用的影响较小，而且从干旱中恢复的IE植株的光合速率也高于NE植株。轻度干旱会刺激异戊二烯的释放。在严重干旱条件下，异戊二烯释放量下降，IE植株中非挥发性类异戊二烯，特别是脱环氧化叶黄素和脱落酸（ABA）的含量高于NE植株。IE植株中可溶性糖和苯丙烷类物质的含量也更高。复水后，IE植株维持着较高的代谢物水平，但异戊二烯释放量再次高于未受胁迫的植株。我们认为转基因烟草中异戊二烯的生成引发了不同的反应，这取决于干旱的严重程度。在干旱条件下，观察到的异戊二烯与非挥发性类异戊二烯之间的权衡表明，在IE植株中异戊二烯起到短期保护剂的作用，而非挥发性类异戊二烯则可抵御严重的长期损害。干旱过后，有人提出释放异戊二烯的能力可能会上调非挥发性类异戊二烯和苯丙烷类物质的生成，这可能会进一步保护IE叶片。
