摘要
根细胞壁对于植物养分吸收积累以及植物的环境抗性或耐性方面的作用和影响与细胞壁表面性质密切相关。本研究采用改进的匀浆洗涤法提取大豆(Glycine maxL.,Type I细胞壁类型植物)、玉米(Zea maysL.,Type II细胞壁类型植物)幼苗的根细胞壁物质,获得了较好的细胞壁材料纯度。测定了根细胞壁材料以及整根的阳离子交换量(CEC),并通过拟合解析根细胞壁的电位滴定曲线求解根细胞壁表面基团的解离常数pKa以及数量。结果表明,大豆的根细胞壁CEC显著(P<0.05)高于玉米的根细胞壁CEC,分别为425±5、162±7μmol/g,DW;大豆的根CEC也显著(P<0.05)高于玉米根,与两种植物根细胞壁CEC的差异一致。从两种植物的根细胞壁上均识别出一种表观pKa值约为5.78的羧基基团。大豆根细胞壁的羧基含量也显著(P<0.05)高于玉米根细胞壁,分别为604±15、252±4μmol/g,DW,大豆根或根细胞壁的CEC较高与Type I细胞壁富含羧基有关。本文还进一步讨论了不同细胞壁类型植物的根细胞壁表面性质对于植物的营养过程以及环境胁迫抗性或耐性方面的影响与意义。
Surface characteristics of root cell walls are thought to closely relate to the effects of root cell walls on nutrient uptake and accumulation as well as resistance or tolerance to environmental stresses in plants. This study used a modified homogenizing-washing scheme to extract cell wall materials from roots of soybean （ Glycine max L., a plant with Type Ⅰ cell wall） and maize （Zea mays L., a plant with Type Ⅱ cell wall） seedlings, rendering root cell wall materials with good purities. The cation exchange capacities （CECs） of extracted root cell wall materials and intact roots were measured, and the dissociation constant and amount of each type of functional group on the surface of root cell walls were estimated by fitting and resolving of the potentiometric titration curves of the root cell walls. It is indicated that the CEC of soybean root cell wall is significantly （ P 〈 0.05） higher than that of maize root cell wall, with values of 425 ± 5 and 162 ± 7 tLmol/g, DW, respectively. The root CEC of soybean is also significantly （ P 〈 0.05） higher than that of maize, which is consistent with the difference between the CECs of root cell walls of the two plants. Only one functional group on the surface of root cell walls of either soybean or maize was identified, which is thought to be the carboxylic acid group with an apparent pKa equivalent to 5.78. The estimated amount of carboxylic group in the root cell wall of soybean was also significantly （ P 〈 0.05） higher than that of maize, with values of 604 ± 15 and 252 ± 4 μmol/g, DW, respectively. The higher CEC of soybean roots or root cell walls is related to more carboxylic groups appeared in Type Ⅰ cell walls. Further discussed was the effect and significance of surface characteristics of root cell walls on nutritional processes as well as resistance or tolerance to environmental stresses in plants with Type Ⅰ or Type Ⅱ cell wall.
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2008年第2期392-397,共6页
Journal of Plant Nutrition and Fertilizers
基金
国家科技部"973"项目(2002CB410810)资助
关键词
根细胞壁
阳离子交换量
活性基团
大豆
玉米
root cell wall
cation exchange capacity
functional groups
soybean
maize
