Fluorometric and histochemical assay of gus activity showed that this approximate 300bp dna fragment was sufficient to direct seed - specific gene expression and the two substitution mutations in b - box led to a slight decrease in the promoter ' s expression efficiency and almost had no effect on its temporal and spatial expression pattern 尽管b盒作为高度保守区在种子特异性表达中起重要作用，位于此处的两个碱基替代型突变并未使nap300的活性明显降低，对启动子的时空表达模式也无明显影响。
