低温胁迫下枇杷叶片细胞超微结构及膜透性和保护酶活性的变化

Changes in cell ultra-structure, membrane permeability and protective enzyme activity in Eriobotrya japonica Lindl. leaves under cold stress

以盆栽"解放钟"嫁接的枇杷结果小苗(Eriobotrya japonica Lindl.)为试材,采用人工降温的方法,研究低温胁迫下枇杷叶片细胞超微结构及膜透性和保护酶活性的变化。结果表明,7℃、2℃低温处理时,枇杷叶片大多数细胞器基本无损,排列有序,PMP、MDA含量先上升后下降,保护酶活性先增大后减小,表明枇杷小苗对7℃、2℃低温逆境有一定的适应能力;-2℃低温胁迫叶绿体双层膜结构破坏严重,类囊体垛叠程度很低,形不成典型的基粒,还可见线粒体双层膜结构,但己经没有明显的内脊,内部呈小泡化,PMP、MDA含量呈一直上升的趋势,保护酶活性受到抑制,表明枇杷结果小苗已经受到冻害;-7℃低温胁迫细胞质膜已经破裂,原生质体浓缩,叶绿体扭曲变形、相互融合,液泡破裂,线粒体膜结构受损,脊消失,PMP、MDA含量大幅度增加,保护酶活性受到严重抑制,表明枇杷营养生长已经受到极为严重的伤害。由此可见,枇杷结果小苗在0℃以下受冻严重,营养生长受阻,从而影响枇杷正常生长以及产量、品质的提高。

Using a pot cultured Eriobotrya japonica Lindl. grafted in ＂Jiefangzhong＂ as an experimental material, changes in E. japonica leaf cell ultra-structure, membrane permeability and protective enzyme activity were determined. The results show that under controlled temperature of 7 ℃ and 2 ℃, most leaf cell organelles of E. japonica are not injured and orderly arrange. PMP and MDA content initially raises and then falls, so also is the protective enzyme activity. This suggests that E. japonica can adapt to chilling temperatures of 7 ℃ and 2 ℃. Under -2 ℃, leaf cell chloroplasts are destroyed. Thylakoid is not packed to its normal grana and therefore fails to form typical structures. Though the mitochondrion membrane structure can still be visible, its cristae number drops. Because of increasing content of PMP and MDA, protective enzyme activity is inhibited. Hence the leaf of E. japonica suffers severe frostbite. Under a temperature stress of -7 ℃, plasma membranes break up and protoplasts become greatly concentrated. In fact chloroplasts entirely decompose. Grana lamellace twists, disfigures and even fuses. Mitochondrion membrane system is completely destroyed and cristae can not be found. PMP and MDA content raises drastically, hence protective enzyme activity is greatly inhibited. The vegetation growth of E. japonica are badly distorted. In summary,E. japonica leaf severely freezes when temperatures fall below zero, which inhibits the vegetation growth of the plant.