Abstract: Rosa beggeriana‘Aurea’is a yellow-leaf mutant of R. beggeriana which is obtained by 60Co-γ irradiation treatment. The chloroplast ultrastructure and photosynthetic pigment content were analyzed in R. beggeriana‘Aurea’and R. beggeriana. The results showed that fewer grana lamellae，with sparsely and irregularly stacking，were observed in the chloroplasts of R. beggeriana‘Aurea’，indicating the chloroplast development of R. beggeriana‘Aurea’was impaired. The content of chlorophyll a，chlorophyll b and carotenoid in leaves of R. beggeriana‘Aurea’was significantly lower，while the chlorophyll a/b ratio was significantly increased in R. beggeriana‘Aurea’，indicating R. beggeriana ‘Aurea’was a chlorophyll b-deficient mutant. The quantification of intermediates and the gene expression of key enzymes in chlorophyll biosynthesis pathway revealed that the content of uroporphyrinogen Ⅲ，coproporphyrinogen Ⅲ，protoporphyrin Ⅸ and Mg-protoporphyrin Ⅸ，as well as the gene expression level of RbHEMC，RbHEME1/RbHEME and RbCHLI，was significantly lower in leaves of R. beggeriana‘Aurea’，indicating the chlorophyll biosynthesis of R. beggeriana ‘Aurea’may be hinderd at the process of synthesizing uroporphyrinogen Ⅲ from porphobilinogen. The coding region of 4 down-regulated genes were cloned and showed the exactly same DNA sequences between the mutant and wild type，which suggested that the blockage in the chlorophyll biosynthesis of R. beggeriana ‘Aurea’was not due to the mutation in the coding region of genes mentioned above，reflecting that the regulation mechanism of leaf color variation remains further exploration.

Key words: rose, Rosa beggeriana‘Aurea’, leaf-color mutant, chlorophyll biosynthesis, gene cloning, gene expression level