INDUCTION OF PATHOGEN DEFENSE GENES IN PARSLEY (PETROSELINUM-CRISPUM L) PLANTS BY OZONE

Parsley (Petroselinum crispum L.) is known to respond to pathogen atta ck by the synthesis of furanocoumarins and to UV-irradiation by the sy nthesis of flavone glycosides, whereas ozone treatment results in the induction of both pathways. Ozone treatment (200 nl l(-1), 10 h) of pa rsley seedlings results in an increased mRNA level of early genes with in 3 h [pathogenesis related proteins PR1, PR2 and an elicitor-induced protein with unknown function (Eli 16)], of intermediate induced gene s within 6h [phenylalanine ammonia-lyase (PAL), 4-coumaroyl-CoA ligase (4CL), chalcone synthase (CHS)], and of late genes within 12 h [hydro xyproline-rich glycoprotein (HRGP), peroxidase (POD)]. 2D-PAGE of in v itro trans lated poly(A)' RNA isolated from ozone-treated parsley seed lings revealed about 20 induced and 10 repressed translation products. A cDNA library from parsley seedlings was differential screened, yiel ding several induced cDNA clones. One of the ozone-induced cDNA clones could be identified as coding for PR1-1 by hybrid-selected in vitro t ranslation and by DNA sequence analysis.