在 0、100、300、500 和 700 mmol· L^-1 NaCl 胁迫条件下比较了喷施 0. 1 mmol· L^-1亚精胺( Spd)对毕氏海蓬子(Salicornia bigelovii Torr.)幼苗叶绿素含量、净光合速率、气孔导度、胞间 CO2浓度和叶绿体超微结构的影响。 结果表明:毕氏海蓬子的叶绿素含量、净光合速率和气孔导度均呈低浓度条件下(0、100 和 300 mmol· L^-1 NaCl)升高、高浓度条件下(500 和 700 mmol· L^-1 NaCl)降低的趋势,在 300 mmol· L^-1 NaCl 胁迫条件下达到最高值;胞间 CO₂浓度则呈低浓度 NaCl 胁迫条件下降低、 500 mmol· L^-1 NaCl 条件下升高、 700 mmol· L^-1 NaCl 条件下略降低的趋势; 在0 ~ 500 mmol· L^-1 NaCl 胁迫条件下叶绿素 a / b 值变化不明显,但在 700 mmol· L^-1 NaCl 条件下急剧降低。 在低浓度 NaCl 胁迫条件下,叶绿体整体膨胀,类囊体片层结构松散,但叶绿体和类囊体结构仍保持完整;而经 500 和 700mmol· L^-1 NaCl 处理后,叶绿体超微结构被严重破坏,叶绿体膜结构破裂、类囊体结构松散呈放射状、有些叶绿体完全解体。 而在相应的 NaCl 胁迫条件下喷施 0. 1 mmol· L^-1 Spd,毕氏海蓬子的叶绿素含量、净光合速率、气孔导度和胞间 CO₂浓度虽然也呈现出相同的变化趋势,但其数值均显著高于对照(未喷施 Spd);且叶绿体超微结构的损伤程度也轻于对照。 研究结果说明:喷施外源 Spd 能够减缓 NaCl 胁迫对毕氏海蓬子的伤害作用。

 

Under 0, 100, 300, 500 and 700 mmol· L^-1 NaCl stress, effects of spraying 0. 1 mmol· L^-1 spermidine (Spd) on chlorophyll content, net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration and chloroplast ultrastructure of Salicornia bigelovii Torr. seedling were compared. The results show that chlorophyll content, net photosynthetic rate and stomatal conductance of S. bigelovii all appear the trend of increasing under low concentration condition (0, 100 and 300 mmol· L-1 NaCl) and decreasing under high concentration condition (500 and 700 mmol· L-1 NaCl) with the highest value under 300 mmol· L^-1 NaCl stress. While intercellular CO₂ concentration appears the trend of decreasing under low concentration NaCl stress, increasing under 500 mmol· L-1NaCl stress and slightly decreasing under 700 mmol· L^-1 NaCl stress. Under 0 -500 mmol· L^-1 NaCl stress, Chla / Chlb value has an un-obvious change, but sharply decreases under 700 mmol· L^-1 NaCl stress. Under low concentration NaCl stress, chloroplast overall swells and thylakoid lamella loosens but structures of chloroplast and thylakoid still remain intact. While under 500 and 700 mmol · L^-1 NaCl stress, chloroplast ultrastructure is damaged seriously with membrane structure rupturing and thylakoid loosening to radial, and some chloroplasts completely disaggregate. After spraying 0. 1 mmol· L-1Spd under corresponding NaCl stress, though chlorophyll content, net photosynthetic rate, stomatal conductance and intercellular CO₂ concentration of S. bigelovii also appear the same change trend, but their values all are significantly higher than those of the control (not spraying Spd) and the damage of chloroplast ultrastructure is also lighter than that of the control. It is suggested that spraying exogenous Spd can alleviate the injury of NaCl stress to S. bigelovii.