节节麦不同生育期叶片蜡质组成和超微形态的变化

为了解节节麦(Aegilops tauschii Coss.)不同生育期叶片表皮蜡质组成及晶体形态的变化,对节节麦叶片蜡质进行提取,利用气相色谱-质谱(GC-MS)联用仪和气相色谱-火焰离子化检测仪(GC-FID)对蜡质进行了定性和定量分析,并采用扫描电镜(SEM)对叶片表面蜡质晶体形态进行了观察。结果表明,节节麦叶表皮蜡质经GC-MS分析,共鉴定出化合物21种,主要以初级醇为主(苗期、抽穗期和灌浆期相对含量分别为85%、84%和70%),并含有少量的烷烃、醛、酮和脂肪酸;随着节节麦的生长发育,蜡质总量不断积累,烷烃含量极显著地升高,其中以C29烷烃的增加最明显,而初级醇含量显著降低,其中C26醇的相对含量降低最明显(苗期、抽穗期和灌浆期相对含量分别为80%、76%和63%),其他各类化合物组分变化不大。经扫描电镜观察,节节麦叶片近轴和远轴面的蜡质晶体形态无明显差别,苗期均为片状,抽穗期大部分仍以片状形态存在,并且蜡质晶体的密集程度比苗期稀疏,灌浆期蜡质晶体的密集程度变得更加稀疏。这些变化可能与抽穗期、灌浆期烷烃含量的增加和初级醇含量的减少有关。

Composition and Ultrastructure Variation of Leaf Culticular Wax at Different Developing Stages of Aegilops tauschii

In order to know the changes of leaf cuticular wax composition and ultrastructure during the developmental growth of Aegilops tauschii, leaves were harvested as the test materials to extract the cuticular waxes. The wax composition and content were qualitatively and quantatively analyzed with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID), and the ultrastructure of leaf cuticular waxes was observed by scanning electron microscope. The results showed that 21 chemical compounds were identified by GC-MS analysis, and the main components of cuticualr waxes were primary alcohols (seedling stage 85%, heading stage 84% and filling stage 70%), with small amounts of alkanes, fatty acids, aldehydes and diketones. With the developmental growth of Aegilops tauschii, the total wax was constantly synthesized, the content of alkanes increased significantly, among which the increase of C₂₉ alkanes was the most significant. however, the content of primary alcohols reduced significantly, especially the relative amount of C₂₆ alcohol (seedling stage 80%, heading stage76%, filling stage 63%), the changes of other components were not obvious. Based on the results of scanning electron microscope, the wax crystal structures of adaxial and abaxial surface were in similar shape of platelets in these three stages. In addition, wax crystals on leaves at heading stage were sparse compared with waxes on leaves at seedling stage and became much sparser at filling stage, which could be caused by the increased amount of alkanes and the decreased amount of alcohols at these stages.