离体完整叶绿体的钾、钠和氯含量与叶片离子区隔化的关系
Potassium, sodium, and chloride content of isolated intact chloroplasts in relation to ionic compartmentation in leaves.
作者信息
Robinson S P, Downton W J
出版信息
Arch Biochem Biophys. 1984 Jan;228(1):197-206. doi: 10.1016/0003-9861(84)90061-4.
Intact chloroplasts were isolated from spinach, sugarbeet, and pea leaves by a rapid procedure which included purification on a two-step Percoll gradient. The content of K+, Na+, and Cl- was determined together with the chloroplast volume from which the apparent concentration of these ions in the chloroplast was calculated. It was demonstrated by successive washing that K+ leaked out of the chloroplasts during isolation whereas Na+ and Cl- did not. For spinach and sugarbeet chloroplasts K+ was the predominant monovalent cation (160-200 mM) with Na+ present in lesser amounts (40-70 mM). Pea chloroplasts contained equal amounts of K+ and Na+ (40 mM). The Cl- concentration in the chloroplast was similar for the three species and was calculated to be near 100 mM. The Cl- concentration in the chloroplast was well above that of the leaf tissue implying accumulation of Cl- in the chloroplast. Qualitatively similar results were obtained for chloroplasts isolated by rapidly fractionating protoplasts of wheat and barley although the concentration of ions was lower than for the above three species. Spinach grown in 200 mM NaCl accumulated high levels of Na+ and Cl- in the leaves but K+ was decreased. The replacement of K+ by Na+ was also observed in the chloroplasts but the level of Cl- in the chloroplast was not greatly increased even at leaf Cl- in excess of 200 mM. Replacement of K+ by Na+ in the nutrient solution also resulted in replacement of K+ by Na+ both in the leaf and in the chloroplast. Spinach grown under Cl- deficiency showed a 70% decrease in growth and a similar decrease in leaf Cl- but the concentration of Cl- in the chloroplast was not significantly decreased. It is concluded that in most instances K+ is the dominant monovalent cation in chloroplasts, although replacement by Na+ can occur to some extent. Chloride is a major anion, being accumulated within the chloroplast at low leaf Cl- and excluded from the chloroplast at high leaf Cl-. Ionic compartmentation within the leaf cell appears to be regulated to maintain a relatively constant level of Cl- in the chloroplast.
采用一种快速方法从菠菜、甜菜和豌豆叶片中分离出完整的叶绿体，该方法包括在两步Percoll梯度上进行纯化。测定了K⁺、Na⁺和Cl⁻的含量以及叶绿体体积，并据此计算出这些离子在叶绿体中的表观浓度。连续洗涤表明，在分离过程中K⁺从叶绿体中泄漏出来，而Na⁺和Cl⁻则没有。对于菠菜和甜菜叶绿体，K⁺是主要的单价阳离子（160 - 200 mM），Na⁺含量较少（40 - 70 mM）。豌豆叶绿体中K⁺和Na⁺含量相等（40 mM）。三种植物叶绿体中的Cl⁻浓度相似，经计算接近100 mM。叶绿体中的Cl⁻浓度远高于叶片组织，这意味着Cl⁻在叶绿体中积累。通过快速分离小麦和大麦原生质体获得的叶绿体也得到了定性相似的结果，尽管离子浓度低于上述三种植物。在200 mM NaCl中生长的菠菜叶片中积累了高水平的Na⁺和Cl⁻，但K⁺含量降低。在叶绿体中也观察到K⁺被Na⁺取代，但即使叶片中Cl⁻超过200 mM，叶绿体中的Cl⁻水平也没有大幅增加。在营养液中用Na⁺取代K⁺也导致叶片和叶绿体中的K⁺被Na⁺取代。在缺Cl⁻条件下生长的菠菜生长量下降了70%，叶片中的Cl⁻也有类似程度的下降，但叶绿体中的Cl⁻浓度没有显著降低。得出的结论是，在大多数情况下，K⁺是叶绿体中的主要单价阳离子，尽管在一定程度上可能被Na⁺取代。氯离子是主要阴离子，在叶片Cl⁻含量低时在叶绿体内积累，在叶片Cl⁻含量高时被排除在叶绿体外。叶片细胞内的离子分隔似乎受到调节，以维持叶绿体中Cl⁻水平相对恒定。
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