心里美萝卜营养生长期肉质根过氧化物酶同工酶谱及组化分析

过氧化物酶［peroxidase，POD，EC 1. 11. 1. 7 (X)］为一类多基因家族的同工酶，其聚合形式对其功能具有重要影响．心里美萝卜(Raphanus sativus var.L) 肉质根富含花青素和POD等．本文采用不同的电泳技术、组化定位和活性测定研究了心里美萝卜营养生长期肉质根中POD在不同时期和不同组织中的表达、分布特点及同工酶的组成和性质．结果显示，心里美萝卜营养生长期肉质根的皮和肉中POD活性均先升高后降低，分别在播种后第40 d和60 d出现峰值，30 d时皮中POD活性高于肉，之后则相反，酶活性最高时同工酶数目也最多，不同时期，皮和肉中同工酶种类不同；皮中POD同工酶由5个单体和4个二聚体组成，而肉中由5个二聚体或2个单体、2个二聚体和1个四聚体组成，均以酸性同工酶为主；组化定位显示POD主要分布在肉质根的周皮、形成层、木射线、木质部导管和肉的初生木质部等的细胞壁附近．从上述结果得出结论： 酸性POD同工酶在植物体中以多种形式存在．

Isoenzymic and Histochemical Analysis of Peroxidase in Root of Chinese Red Radish During Vegetative Growth

Peroxidases ［PODs，EC 1. 11. 1. 7 (X)］are isoenzymes encoded by multigene family. The functions of POD are closely related to its aggregated forms. The root of Chinese red radish (Raphanus sativus var.L) is considered to be a rich source of POD and anthocyanin etc. In this study, the expression, distribution, composition and characteristic of POD isoenzymes were investigated in different tissues of Chinese red radish root during vegetative growth by different electrophoresis methods, histochemical location and measurement of POD activity. The results showed that POD activity increased at first and then decreased in the skin and flesh of root. The peak occurred at 40 d and 60 d in the skin and flesh, respectively. POD activity in the skin was higher than that in the flesh at 30 d and then contrary results were observed. The higher POD activity was, the more POD isoenzyme was. The pattern of POD isoenzymes was different between skin and flesh at different vegetative growth stages. POD isoenzymes in the skin were composed of five monomers and four dimers while five dimers or two monomers, two dimers and one tetramer in the flesh. POD isoenzymes in the root were mainly acidic. POD localized mainly in the cell walls of periderm, cambium, xylem ray, xylem vessels and primary xylem. We concluded that acidic POD isoenzymes may exist in many forms in plants.