RNAi-mediated suppression of the phenylalanine ammonia-lyase gene in Salvia miltiorrhiza causes abnormal phenotypes and a reduction in rosmarinic acid biosynthesis.
Medicinal Salvia miltiorrhiza contains two main groups of active pharmaceutical ingredients: lipid-soluble tanshinones and water-soluble phenolic acids, including rosmarinic acid and salvianolic acid B. Phenylalanine ammonia-lyase (PAL) catalyzes the first step in the phenylpropanoid pathway and is assumed to be closely related to the accumulation of rosmarinic acid and its derivatives. We selected a 217-bp fragment, located at the 3' end of the coding region of PAL1, to establish an RNA interference construct that was introduced into S. miltiorrhiza via Agrobacterium tumefaciens-mediated transformation. PAL-suppressed plants exhibited several unusual phenotypes such as stunted growth, delayed root formation, altered leaves, and reduced lignin deposition. The total phenolic content was decreased by 20-70% in PAL-suppressed lines, and was accompanied by lower PAL activity. Down-regulation of PAL also affected the expression of C4H, 4CL2, and TAT, which are related genes in the rosmarinic acid pathway. Moreover, rosmarinic acid and salvianolic acid B were markedly reduced in PAL-suppressed lines, as detected by HPLC analysis. Our results indicate that PAL is very important for the synthesis of major water-soluble pharmaceutical ingredients within S. miltiorrhiza.
Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest of China, Shaanxi Normal University, Xi'an 710062, People's Republic of China.
Jie
J
Song
Zhezhi
Z
Wang
D002934:Cinnamates / Q000737:chemistry / Q000378:metabolism*; D053630:Depsides / Q000737:chemistry / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D005822:Genetic Vectors / Q000235:genetics; D010641:Phenotype; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics*; D030821:Plants, Genetically Modified; D034622:RNA Interference; D027561:Salvia miltiorrhiza / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics*; D013489:Suppression, Genetic; D000097123:Rosmarinic Acid
D002934:Cinnamates; D053630:Depsides; D010650:Phenylalanine Ammonia-Lyase; D000097123:Rosmarinic Acid