根施甜菜碱对水分胁迫下烟草幼苗光合机构的保护

以烟草品种大黄金5210（抗旱性强）和中烟100（抗旱性弱）为材料，研究了水分胁迫对烟草叶片光合机构的影响，并通过根部施用甜菜碱的方法，探讨了甜菜碱对烟草光合机构的保护作用。结果表明：水分胁迫导致烟草幼苗光合机构损伤，表现在叶绿素含量、PSII光化学效率、希尔反应活力以及类囊体膜ATPase活性下降，且对抗旱性弱的中烟100损伤更加严重。外源甜菜碱处理减轻了水分胁迫对以上指标的降低程度，特别是对干旱敏感型烟草品种中烟100的效果更加明显。甜菜碱的这种保护作用可能与它能够维持叶片中各种抗氧化酶活性、减轻活性氧的积累、保护类囊体膜上各种色素蛋白的功能以及缓解水分胁迫对膜的破坏作用有关。

Glycinebetaine Applied through Roots Protects the Photosynthetic Apparatus of Tobacco Seedlings under Water Stress

Two tobacco (Nicotiana tabacum L.) cultivars (DHJ5210 and ZY100) with different drought tolerance were used to study the photo- synthetic response to different water stress and the effects of glycinebetaine applied through roots on photosynthetic capacity. The physiological mecha- nisms of the improvement of tobacco photosyn- thesis by glycinebetaine applied through roots were analyzed. The results indicated that photosynthetic apparatus of tobacco leaves were more brittle and damaged by water stress, accompanied by nega- tive changes of RWC (Fig.2), chlorophyll content (Fig.3), PSII photochemistry efficiency (Fig.4), activity of Hill reaction (Fig.5) and ATPase (Fig. 6), and the damage was more serious to ZY100 (drought sensitive cultivar) than DHJ5210 (drought resistant cultivar) under the same stress condition.Glycinebetaine applied through roots could be ab- sorbed by tobacco roots and then accumulated in leaves (Fig.1), which alleviated the decrease in photosynthetic variables of two cultivars and the improvement was more significant on ZY100 than DHJ5210. The positive function of glycinebetaine might be involved in its protective effect on anti- oxidant enzymes (Fig.8), chloroplast protein and thylakoid membrane (Fig.7).