Kalemba Ewa Marzena, Suszka Jan, Ratajczak Ewelina
Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland.
Funct Plant Biol. 2015 Jun;42(7):630-642. doi: 10.1071/FP14336.
Black poplar (Populus nigra L.) is one of the most threatened tree species in Europe since up to 99% of its natural habitat has disappeared. Black poplar seeds are characterised by short longevity. It was recently demonstrated that black poplar seeds can be successfully stored at -10°C, -20°C and -196°C for at least 2 years but not at higher temperatures. In the present study, the role of oxidative stress in determining the level of viability of black poplar seeds stored at -196°C, -20°C, -10°C, -3°C and 3°C for 3 months, 1 year and 2 years was monitored. The superoxide anion radicals (O2-•) and hydrogen peroxide (H2O2) increased during storage and had an impact on membrane integrity as determined by changes in the content of fatty acids and phospholipids and increases in electrolyte leakage. The level of non-enzymatic and enzymatic components of the ascorbate-glutathione (AsA-GSH) cycle was also investigated. The level of O2-• was strongly correlated with the level of seed germination after 1 and 2 years of storage. This was accompanied by changes in the redox potential, as well as changes in the content of linoleic acid and phosphatydiloglycerol over the same period of time. In particular, the deleterious effect of H2O2 was observed after 2 years of storage when its accumulation was highly correlated with changes in the composition of fatty acids and phospholipids. Despite increased activity of AsA-GSH cycle enzymes, the level of reducing agents was insufficient and seeds exhibited large increases in the redox potential when stored at -3°C and still higher when stored at 3°C. Overall, the results of the study demonstrate that oxidative stress increases during seed storage, especially at the warmer temperatures and injures seed tissues; resulting in a loss of viability.
黑杨（Populus nigra L.）是欧洲受威胁最严重的树种之一，因为其高达99%的自然栖息地已经消失。黑杨种子的特点是寿命短。最近有研究表明，黑杨种子能够在-10°C、-20°C和-196°C下成功储存至少2年，但在更高温度下则不行。在本研究中，监测了氧化应激在决定黑杨种子在-196°C、-20°C、-10°C、-3°C和3°C下储存3个月、1年和2年时的活力水平方面所起的作用。超氧阴离子自由基（O2-•）和过氧化氢（H2O2）在储存过程中增加，并通过脂肪酸和磷脂含量的变化以及电解质渗漏的增加对膜完整性产生影响。还研究了抗坏血酸-谷胱甘肽（AsA-GSH）循环的非酶和酶成分水平。O2-•的水平与储存1年和2年后的种子发芽水平密切相关。与此同时，氧化还原电位发生了变化，亚油酸和磷脂酰甘油的含量也发生了变化。特别是，在储存2年后观察到了H2O2的有害影响，此时其积累与脂肪酸和磷脂组成的变化高度相关。尽管AsA-GSH循环酶的活性增加，但还原剂的水平不足，种子在-3°C储存时氧化还原电位大幅升高，在3°C储存时更高。总体而言，研究结果表明，种子储存期间氧化应激增加，尤其是在较高温度下，会损害种子组织，导致活力丧失。
