玉米不同类型愈伤组织分化中硝态氮代谢的差异分析

The Variation Analysis of Nitrate-nitrogen Metabolism of Different Types of Maize Callus in the Process of Callus Differentiation

以玉米自交系齐319幼胚产生的Ⅰ型和Ⅱ型愈伤组织为材料,对其分化过程中的硝酸盐、亚硝酸盐含量及硝酸还原酶(NR)、亚硝酸还原酶(NiR)活性进行了测定,并对2种类型的愈伤组织在硝态氮代谢方面的异同进行了比较。结果表明,2种愈伤组织刚转入分化培养基时NR活性显著增强,之后逐渐下降;在分化过程中,Ⅱ型愈伤组织的NiR活性始终高于Ⅰ型;2种愈伤组织的硝酸盐含量在分化中没有明显差别;从分化第6天到第19天,Ⅱ型愈伤组织的亚硝酸盐含量一直低于Ⅰ型。分析可知,Ⅱ型愈伤组织的幼苗分化率高于Ⅰ型,与愈伤组织的硝酸盐含量关系不大,主要与亚硝酸盐含量有关,而亚硝酸盐含量的高低直接决定于NiR的活性,因此,NiR的活性对玉米愈伤组织分化具有重要的影响。

This study measured nitrate,nitrite content and the activity of nitrate reductase（NR） and nitrite reductase（NiR） during the process of callus differentiation by using type Ⅰ and type Ⅱ callus from the immature embryo of maize inbred lines Qi319,and compared the differences and similarities between type Ⅰ and type Ⅱ callus in nitrate-nitrogen metabolism.The results were as followed：the activity of NR in two kinds of calli increased significantly at the beginning of differentiation culture and then declined gradually.During the process of callus differentiation,the activity of the NiR in type Ⅱ callus was always higher than that in type Ⅰ callus,and there were no obvious differences between the nitrate content of type Ⅰ and type Ⅱ callus.The nitrite content of type Ⅱ callus was always lower than that of type Ⅰ callus from the sixth day to the nineteenth day on the differentiation medium.It was observed that the rate of the plant regeneration of type Ⅱ callus was higher than that of type Ⅰ callus,which was basically related to nitrite content and was no obvious relation to nitrate content.The nitrite content was dependent on the activity of NiR.It was concluded that the activity of NiR had a significant influence on the callus differentiation in maize.