Effects of foliar application of 100mmol/L glycinebetaine (GB) on PS II photochemistry in wheat (Triticum aestivum) flag leaves under drought stress combined with high irradiance were investigated. The results show that GB-treated plants maintained a higher net photosynthetic rate during drought stress than non-GB treated plants. Exogenous GB can preserve the photochemical activity of PSII, for GB-treated plants maintain higher maximal photochemistry efficiency of PSII (Fv/Fm) and recover more rapidly from photoinhibition. In addition, GB-treated plants can maintain higher anti-oxidative enzyme activities and suffer less oxidative stress. Our data suggest that GB may protect the PSII complex from damage through accelerating D1 protein turnover and maintaining anti-oxidative enzyme activities at higher level to alleviate photodamage. Diethyldithiocarbamate as well as streptomycin treatment can impair the protective effect of GB on PSII. In summary, GB can enhance the photoinhibition tolerance of PSII.

Two wheat cultivars, HF9703 (drought tolerant) and SN215953 (drought sensitive) were used to examine the effects of glycinebetaine (GB, 100 mM) on lipid composition and function of thylakoid membranes under drought stress. GB application mitigated negative effect of drought on Ca2+-ATPase and Hill reaction activities, chlorophyll content, gas exchange and photosynthesis. These positive effects of GB application maybe, in part, correlated with improving the lipid composition of the thylakoid membranes.

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。

以2个小麦品系旱丰9703（抗旱性强）和山农215953（抗旱性弱）为材料，研究了对盐胁迫的反应，以及外源甜菜碱在提高小麦抗盐性方面的作用。结果表明，盐胁迫导致小麦幼苗类囊体膜脂脂肪酸组分相对含量发生改变，山农215953的磷脂酰甘油（PG）和磷脂酰胆碱（PC）中亚麻酸（18：3）相对含量均显著下降，旱丰9703仅PC中亚麻酸（18：3）相对含量显著下降。甜菜碱预处理能显著缓解盐胁迫导致的山农215953的PG和旱丰9703的PC中18：3相对含量的下降。盐胁迫导致小麦幼苗类囊体Ca2+-ATPase活性、Hill反应活力和叶绿素含量及光合作用的降低，抗旱性较弱的山农215953下降程度较大；甜菜碱预处理能显著缓解其下降程度。抗旱性不同的小麦品系在抗盐性方面具有相同的趋势。