Arora Dhara, Bhatla Satish C
Laboratory of Plant Physiology and Biochemistry, Department of Botany, University of Delhi, Delhi 110007, India.
Free Radic Biol Med. 2017 May;106:315-328. doi: 10.1016/j.freeradbiomed.2017.02.042. Epub 2017 Feb 28.
Salinity results in significant reduction in sunflower (Helianthus annuus L.) seedling growth and excessive generation of reactive oxygen species (ROS). Present work highlights the possible role of melatonin as an antioxidant through its interaction with nitric oxide (NO), and as an early and long distance NaCl-stress sensing signaling molecule in seedling cotyledons. Exogenous melatonin (15µM)±NaCl (120mM) inhibit seedling growth, which is also correlated with NO availability, accumulation of potential superoxide anion (O) and peroxynitrite anion (ONOO), extent of tyrosine-nitration of proteins, spatial localization and activity of superoxide dismutase (SOD) isoforms. NO acts as a positive modulator of melatonin accumulation in seedling cotyledons as a long-distance signaling response. Modulation of superoxide anion and peroxynitrite anion content by melatonin highlights its crucial role in combating deleterious effects of ROS and reactive nitrogen species (RNS). Present findings provide evidence for an interaction between melatonin and NO in their effect on seedling growth under salt stress accompanying differential modulation of two SOD isoforms, i.e. Cu/Zn SOD and Mn SOD.
盐分导致向日葵（Helianthus annuus L.）幼苗生长显著降低，并产生过量的活性氧（ROS）。目前的研究强调了褪黑素作为抗氧化剂通过与一氧化氮（NO）相互作用的可能作用，以及作为幼苗子叶中早期和远距离NaCl胁迫传感信号分子的作用。外源褪黑素（15µM）±NaCl（120mM）抑制幼苗生长，这也与NO的可用性、潜在超氧阴离子（O）和过氧亚硝酸盐阴离子（ONOO）的积累、蛋白质酪氨酸硝化程度、超氧化物歧化酶（SOD）同工型的空间定位和活性相关。NO作为远距离信号响应，是幼苗子叶中褪黑素积累的正向调节剂。褪黑素对超氧阴离子和过氧亚硝酸盐阴离子含量的调节突出了其在对抗ROS和活性氮物种（RNS）有害影响中的关键作用。目前的研究结果为褪黑素和NO在盐胁迫下对幼苗生长影响中的相互作用提供了证据，同时伴随着两种SOD同工型即铜/锌SOD和锰SOD的差异调节。
