Comparison of regional permeability and translocation across the node and the internode in the etiolated mesocotyl excised from corn ( Zea mays L.) seedling was made before and after treatment with different concentrations of acetylcholine (AChs). Regional permeability was determined by electrical resistance measurement; and translocation by detecting the distribution of the fluorescent probe (carboxyfluorescein, CF), fed at the cut end of the etiolated coleoptile. The cells constituting the internode were more or less cylindrical in size and arranged more or less parallel to the long axis, whereas those in the node were shorter in length and arranged irregularly. The results showed that the specific electrical resistance across the node was higher than that across the internode. Consequently, short nodal cells with lower intercellular permeability retained more CF than that in the cylindrical internodal cells. Treatment with 0.1 mmol/L ACh could increase the permeability of both node and internode, thus promoting higher rate of CF translocation than that of the control. Variation in material translocation across the node and the internode, as well as its modulation by ACh treatment, can be largely attributed to differences in their intercellular permeability.
乙酰胆碱对黄化玉米幼苗中胚轴通透性与物质运转的调控效应
兰平 娄成后
（中国农业大学生物学院，农业部植物生理生化重点开放实验室，北京100094）
摘要：对乙酰胆碱处理前后的黄化玉米 (ZeamaysL .)幼苗中胚轴切段节和节间的通透性和物质运转进行了比较。用电阻法测定通透性 ;通过加在胚芽鞘切口的经共质体转运的特异荧光物质羧基荧光素 (carboxyfluorescein ,CF)的分布检察物质运转。节间由柱状的、排列方向多少和长轴方向平行的细胞构成 ;而构成节的细胞短、排列不规则。结果表明跨节比电阻比节间的高 ,通透性低的短的节细胞比柱状节间细胞累积更多的CF。 0 .1mmol/L乙酰胆碱 (ACh)处理增加了节和节间的通透性 ,促进了CF的运转。物质在节和节间运转的不同 ,以及ACh对此的调控效应很大程度上可归结于细胞通透性的差异
关键词： 乙酰胆碱；电阻；节；羧基荧光素；运输
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