低温胁迫对枇杷幼果细胞超微结构及膜透性和保护酶活性的影响

Effects of Chilling Stress on Cell Ultrastructure and Membrane Permeability and Protective Enzyme Activity in Young Loquat Fruits

以解放钟枇杷(Eriobotrya japonica Lindl.)幼果为试验材料,采用人工降温的方法,研究低温胁迫下枇杷幼果超微结构及膜透性和保护酶活性的变化。结果表明,6和3℃低温胁迫时,枇杷幼果果肉细胞质膜、液泡膜清晰,叶绿体、线粒体结构没有明显的变化,PMP(Plasma Membrane Permeablity,细胞膜透性)、MDA (Malondialdehyde,丙二醛)含量先增加后减少,保护酶活性先增大后减小,且一直维持较高水平,表明有一定的低温适应能力;0℃低温处理原生质膜结构完整,少数叶绿体出现部分解体,双层膜有部分破裂现象,线粒体结构仍清晰可见,PMP、MDA含量、酶活性变化同6和3℃低温胁迫相类似,表明枇杷幼果对0℃低温有一定的适应能力;-3℃低温胁迫下,原生质膜、液泡膜均破裂,原生质体浓缩,叶绿体扭曲变形、相互融合,线粒体膜结构受损,脊消失,PMP、MDA含量均达到最高,保护酶活性受到极为严重的抑制,表明枇杷幼果已经受到冻害。

Under controlled temperature condition, the uhrastructural changes and membrane permeability and protective enzyme activity were studied in young loquat fruits （Eriobotrya japonica Lindl.） The results showed that plasma membrane and tonoplast could be observed clearly, and that chloroplasts and mitochondria did not show any significant changes at 6℃ or 3℃. The contents of PMP and MDA were raised at the initial stage of cold stress and then declined; the activity of protective enzyme raised first and then declined too, and their activity maintained high. These changes indicated loquat young fruit was adapted to the cold stress at 6℃ or 3℃; under 0℃ cold stress, plasmic membrane and tonoplast structure were not injured, the structure of mitochondrion was clear under electromicroscope, changes of PMP, MDA and enzyme activity were similar at 6℃ or 3℃.These changes indicated Jiefangzhong loquat fruit were still adapted to 0℃ cold stress; under -3℃ cold stress, plasmic membrane was already broken, protoplast was concentrated greatly, chloroplasts were decomposed completely, grana lamellace twisted and disordered, even fused; membrane system of mitochondrion was totally destroyed, and cristae could not be found; PMP and MDA content was raised to maximum. The activity of protective enzymes was inhibited highly. These changes presented that Jiefangzhong young fruit were injured under -3℃ cold stress.