Characterization of a novel lipoxygenase-independent senescence mechanism in Alstroemeria peruviana floral tissue
Characterization of a novel lipoxygenase-independent senescence mechanism in Alstroemeria peruviana floral tissue
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DOI：
10.1104/pp.000919
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发表时间：
2002-09-01
期刊：
影响因子：
7.4
通讯作者：
Griffiths, G
中科院分区：
文献类型：
--
作者：
Leverentz, MK;Wagstaff, C;Griffiths, G
采用体外测定和脂氧化产物化学分析相结合的方法，研究了脂氧合酶(LOX)在紫球花朵衰老过程中的作用。在花冠和花瓣衰老过程中，磷脂和半乳糖脂被大量降解，饱和/不饱和脂肪酸的比例增加。LOX蛋白水平和酶活性在开花后显著下降。对LOX产物的立体化学分析表明，13-LOX是花组织中存在的主要活性物质，还合成了高水平的13-酮脂肪酸。膜脂过氧化氢在花瓣中积累，但不在花瓣中积累，并且花瓣中也有较高的叶绿素/类胡萝卜素比率，这有利于脂类的光氧化。膜半通透性的丧失在两种组织类型中都是一致的，并且在时间上与电解质渗漏开始时下降了80%的LOX活性是分开的。因此，膜功能的丧失与LOX活性或脂质过氧化本身的积累无关，在这些方面与其他乙烯不敏感的花组织不同，代表了一种新的花衰老模式。
The role of lipoxygenase (lox) in senescence of Alstroemeria peruviana flowers was investigated using a combination of in vitro assays and chemical profiling of the lipid oxidation products generated. Phospholipids and galactolipids were extensively degraded during senescence in both sepals and petals and the ratio of saturated/unsaturated fatty acids increased. Lox protein levels and enzymatic activity declined markedly after flower opening. Stereochemical analysis of lox products showed that 13-lox was the major activity present in both floral tissues and high levels of 13-keto fatty acids were also synthesized. Lipid hydroperoxides accumulated in sepals, but not in petals, and sepals also had a higher chlorophyll to carotenoid ratio that favors photooxidation of lipids. Loss of membrane semipermeability was coincident for both tissue types and was chronologically separated from lox activity that had declined by over 80% at the onset of electrolyte leakage. Thus, loss of membrane function was not related to lox activity or accumulation of lipid hydroperoxides per se and differs in these respects from other ethylene-insensitive floral tissues representing a novel pattern of flower senescence.