Velikova Violeta, Pinelli Paola, Pasqualini Stefania, Reale Lara, Ferranti Francesco, Loreto Francesco
Institute of Plant Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
New Phytol. 2005 May;166(2):419-25. doi: 10.1111/j.1469-8137.2005.01409.x.
Isoprene reduces visible damage (necrosis) of leaves caused by exposure to ozone but the mechanism is not known. Here we show that in Phragmites leaves isoprene emission was stimulated after a 3-h exposure to high ozone levels. The photosynthetic apparatus of leaves in which isoprene emission was inhibited by fosmidomycin became more susceptible to damage by ozone than in isoprene-emitting leaves. Three days after ozone fumigation, the necrotic leaf area was significantly higher in isoprene-inhibited leaves than in isoprene-emitting leaves. Isoprene-inhibited leaves also accumulated high amounts of nitric oxide (NO), as detected by epifluorescence light microscopy. Our results confirm that oxidative stresses activate biosynthesis and emission of chloroplastic isoprenoid, bringing further evidence in support of an antioxidant role for these compounds. It is suggested that, in nature, the simultaneous quenching of NO and reactive oxygen species by isoprene may be a very effective mechanism to control dangerous compounds formed under abiotic stress conditions, while simultaneously attenuating the induction of the hypersensitive response leading to cellular damage and death.
异戊二烯可减少因暴露于臭氧而导致的叶片可见损伤（坏死），但其机制尚不清楚。在此我们表明，在3小时暴露于高浓度臭氧后，芦苇叶片中的异戊二烯排放受到刺激。与排放异戊二烯的叶片相比，用磷霉素抑制异戊二烯排放的叶片的光合机构更容易受到臭氧的损伤。臭氧熏蒸三天后，抑制异戊二烯排放的叶片中的坏死叶面积显著高于排放异戊二烯的叶片。通过落射荧光显微镜检测发现，抑制异戊二烯排放的叶片还积累了大量一氧化氮（NO）。我们的结果证实，氧化应激激活了叶绿体类异戊二烯的生物合成和排放，为这些化合物的抗氧化作用提供了进一步的证据。有人提出，在自然界中，异戊二烯对一氧化氮和活性氧的同时淬灭可能是一种非常有效的机制，可控制在非生物胁迫条件下形成的危险化合物，同时减弱导致细胞损伤和死亡的过敏反应的诱导。
