VIEW ARTICLE

Effect of Ethrel and Ceratocystis fimbriata on the Accumulation of Chlorogenic acid and 6-Methoxy Mellein in Carrot Root. J. G. Jaworski, Department of Biochemistry, Purdue University, Lafayette, Indiana 47907; J. Kuc(2), and E. B. Williams(3). (2)Department of Biochemistry and Department of Botany and Plant Pathology, Purdue University, Lafayette, Indiana 47907; (3)Department of Botany and Plant Pathology, Purdue University, Lafayette, Indiana 47907. Phytopathology 63:408-413. Accepted for publication 24 September 1972. DOI: 10.1094/Phyto-63-408.

The concentration of 6-methoxy mellein (MM) increased in the upper millimeter of carrot discs treated with a solution of Ethrel (2-chloroethyl phosphonic acid). The concentration during a 5-day interval after treatment was equal to or slightly greater than that in discs inoculated with Ceratocystis fimbriata. Little or no MM was found in fresh or aged discs. MM accummulation increased in carrots treated with increasing concentrations of Ethrel up to 9 mg Ethrel/ml. Chlorogenic acid concentration in the upper millimeter of carrot discs increased to 3.2 mg/g fresh wt of tissue 5 days after inoculation with C. fimbriata, whereas the concentration in untreated and Ethrel-treated carrots increased only to 0.67 and 0.37 mg, respectively. Phenylalanine ammonia-lyase (PAL) activity increased 6-fold in carrots 16 hr after inoculation, whereas the activity in untreated and Ethrel-treated carrots rose 3-fold. The PAL activity decreased in infected tissue after reaching a maximum 16 hr after treatment. Three days after inoculation with C. fimbriata, the concentration of MM was twice as high in the phloem as in the xylem of carrot root discs, whereas the chlorogenic acid concentration was equal to or somewhat higher in the xylem than the phloem. Fungitoxic levels of exogenous MM inhibited growth of the fungus on the xylem and phloem.