关键词: 桃, DA-6, 叶绿素, 合成, 前提物质, 关键酶, 酶活性

Abstract: Taken ‘Xiangshan Honey’ peach as the material，the change of chlorophyll precursor contents and activity of the key enzymes in chlorophyll biosynthesis pathway after DA-6 （N-diethylaminoethyl hexanote）application were investigated the underlying mechanism of DA-6 induced leaf chlorophyll content increase. Compared with the control，20 mg · L^-1 foliar DA-6 spray significantly increased the contents of chlorophylls，especially that of chlorophyll b，and chlorophyll intermediate products porphobilinogen（PBG）and uroporphyrinoge（Urogen Ⅲ），whereas decreased the amount of chlorophyll precursor 5-aminolevulinic acid（ALA）. The results suggested the transformation from ALA to PBG and PBG to Urogen Ⅲ was up-regulated. The key enzymes catalyzing the two reactions are 5-aminolevulinate dehydratase（ALAD）and uroporporphyrinogn Ⅲ synthase（UROS），their enhanced activity after DA-6 foliar spraying was assayed. Our study demonstrated that foliar spray DA-6 increased the conversion efficiency of ALA to PBG and PBG to Urogen Ⅲ，up-regulated the chlorophyll biosynthesis pathway and resulted in higher chlorophyll content in peach leaves.

Key words: peach, DA-6, chlorophyll, biosynthesis, precursors, key enzyme, enzyme activity