低氧胁迫对黄瓜幼苗生长和形态结构及有关酶活性的影响

Effect of hypoxia stress on growth,morpho-anatomical acclimation and activity of involved enzymes of cucumber seedlings

[目的]本文旨在研究根际低氧胁迫对黄瓜幼苗生长、形态解剖结构及有关酶活性的影响。[方法]以耐低氧性较弱的‘中农6号’黄瓜品种为材料,采用营养液通N2形成低氧逆境的方法,深入探讨了根际低氧逆境对黄瓜幼苗生长、形态结构及细胞壁降解、乙烯合成有关酶活性的影响。[结果]根际低氧胁迫7 d后,黄瓜幼苗生长受到显著抑制,植株干质量、叶面积、叶长、根长、根尖数均显著低于通气对照,相对生长率大幅降低;幼苗叶片组织细胞结构致密度增大,栅栏组织的相对比例增加;下胚轴部分肿胀,出现大量皮孔和不定根,皮层薄壁组织细胞之间相互分离出现孔隙;根系伸长区皮层出现通气组织。低氧胁迫初期黄瓜幼苗乙烯生成速率显著提高,乙烯合成酶活性明显增加;根系和下胚轴中与细胞壁降解有关的酶活性也显著提高。[结论]低氧胁迫下黄瓜幼苗生长受到抑制,植株形态、解剖结构发生变化,乙烯合成和细胞壁降解被促进。

[Objectives]The aim of this paper was to investigate the effect of hypoxia on growth,morpho-anatomical acclimation and activity of enzymes involved in cell wall degradation and ethylene biosynthesis of cucumber seedlings. [Methods]A hypoxia-sensitive cucumber genotype（ Cucumis sativus L.‘Zhongnong 6＇） was used and we investigated the effect of hypoxia on growth,morpho-anatomy and ethylene biosynthesis of seedlings under hypoxia stress. The activity of enzymes involved in cell wall degradation was also determined. [Results]After 7 d hypoxia stress,growth of the seedlings was inhibited significantly,with dry weight,leaf growth,root length and number of root tips being decreased greatly. Leaf tissue was compacted under hypoxia stress with the ratio of palisade cell increasing. The root base was swelling,meanwhile many lenticel and adventitious roots appeared on the hypocotyl. Aerenchyma was formed in the root elongation zone of the seedlings. Ethylene production of the seedlings under hypoxia stress was improved,with1-aminocyclopropane-1-carboxylate synthase（ ACS） activity being increased significantly. Also the enzymes involved in cell wall degradation were activated in roots and hycopotyls. [Conclusions]The cucumber seedlings under hypoxia stress undergone morphological and anatomical changes,with ethylene biosynthesis and cell wall degradation being stimulated.