The biosynthesis of phytoalexins in Dianthus caryophyllus L. cell cultures: induction of benzoyl-CoA:anthranilate N-benzoyltransferase activity.
It has been shown that cell cultures of Dianthus caryophyllus L. c.v. Eleganz accumulate N-benzoyl-4-methoxyanthranilic acid, previously identified as the phytoalexin methoxydianthramide B, in response to treatment either with a crude elicitor isolated from the cell walls of Phytophthora megasperma f.sp. glycinea or with a commercial yeast extract. Cell-free extracts from the induced cells efficiently catalyzed the N-benzoylation of anthranilate in the presence of benzoyl-CoA. The partially purified transferase was shown to be specific for anthranilate with almost no activity toward 4-hydroxyanthranilate, whereas acyl donors other than benzoyl-CoA such as salicyloyl-, cinnamoyl-, or 4-coumaroyl-CoA were also accepted. Elicitor treatment of the cells additionally induced an S-adenosyl-L-methionine:N-benzoyl-4-hydroxyanthranilate 4-O-methyltransferase activity. We propose, therefore, that methoxydianthramide B is derived from N-benzoylanthranilic acid via N-benzoyl-4-hydroxyanthranilic acid. Dark-grown cells contained little N-benzoyltransferase activity (approx 8 mu kat/kg), which increased roughly ninefold within 6 h following the addition of the elicitor. In addition, phenylalanine ammonia-lyase activity of the cells increased about twofold under these conditions to a maximum (approx 40 mu kat/kg) at 5 h. The rapid induction of both enzyme activities suggests that the shikimate pathway is of crucial importance in the disease resistance response of carnation cells.
Reinhard
K
K
Biologisches Institut II. Biochemie der Pflanzen, Universität Freiburg, Schänzlestrasse 1, Federal Republic of Germany.
Matern
U
U
D000217:Acyltransferases / Q000096:biosynthesis*; D002474:Cell-Free System; D002478:Cells, Cultured; D004790:Enzyme Induction; D007700:Kinetics; D015394:Molecular Structure; D010936:Plant Extracts / Q000302:isolation & purification / Q000378:metabolism*; D010944:Plants / Q000201:enzymology*; D012717:Sesquiterpenes; D013729:Terpenes; D000094162:Phytoalexins
D010936:Plant Extracts; D012717:Sesquiterpenes; D013729:Terpenes; D000217:Acyltransferases; C061564:benzoyl-CoA-anthranilate N-benzoyltransferase; D000094162:Phytoalexins