Rapid, transient, and highly localized induction of plastidial ω-3 fatty acid desaturase mRNA at fungal infection sites in  Petroselinum crispum

Abstract

Parsley (Petroselinum crispum) plants and suspension-cultured cells have been used extensively for studies of non-host-resistance mechanisms in plant͞pathogen interactions. We now show that treatment of cultured parsley cells with a defined peptide elicitor of fungal origin causes rapid and large changes in the levels of various unsaturated fatty acids. While linoleic acid decreased and linolenic acid increased steadily for several hours, comparatively sharp increases in oleic acid followed a biphasic time course. In contrast, the overall level of stearic acid remained unaffected. Using a PCR-based approach, a parsley cDNA was isolated sharing high sequence similarity with -3 fatty acid desaturases. Subsequent isolation and characterization of a fulllength cDNA enabled its functional identification as a plastidlocalized -3 fatty acid desaturase by complementation of the Arabidopsis thaliana fad7͞8 double mutant which is low in trienoic fatty acids. -3 Fatty acid desaturase mRNA accumulated rapidly and transiently in elicitor-treated cultured parsley cells, protoplasts, and leaves, as well as highly localized around fungal infection sites in parsley leaf buds. These results indicate that unsaturated fatty acid metabolism is yet another component of the highly complex, transcriptionally regulated pathogen defense response in plants.

Biosynthesis and function of polyacetylenes and allied natural products

“…In Petroselinum crispum, the fungal elicitor peptide Pep25 has been shown to stimulate rapid 18:3 9c,12c,15c (α-linolenate, 2P) production and, concomitantly, decrease 18:2 levels over a 2-hour period in cultured cells, protoplasts, and plant leaves [101]. α-Linolenate is a necessary lipid for the biosynthesis of the octadecanoid jasmonate in plants, a signaling component involved in defensive response and development, while polyunsaturated fatty acids generally provide an oxidative sink to consume reactive oxygen species [102].…”

Transcriptional Profiling of Sorghum Induced by Methyl Jasmonate, Salicylic Acid, and Aminocyclopropane Carboxylic Acid Reveals Cooperative Regulation and Novel Gene Responses

“…5). Also potentially related to oxylipin signaling, a sorghum gene (BI245631) with homology to a JA-regulatory protein from Arabidopsis was strongly upregulated by both SA and MeJA at the 27-h time point, while MeJA specifically, strongly, and rapidly induced transcription of an apparent w-3 fatty acid desaturase homolog (BG048471; Table I, Fatty acid metabolism/ JA synthesis), a lipid modification enzyme previously implicated in response to fungal elicitation (Kirsch et al, 1997).…”

Rapid and Transient Induction of a Parsley Microsomal [delta]12 Fatty Acid Desaturase mRNA by Fungal Elicitor

“…Cells were harvested by centrifugation and the pellet was lyophilized and subsequently treated with 1 mL of methanolic HCI. Preparation of the fatty acid methyl esters and GC analysis were performed as described by Kirsch et al (1997). The fatty acid methyl esters were identified by comparison of their retention times with those of authentic standards.…”

“…Using a cDNA encoding a plastid-localized w-3 FAD and two partial cDNAs representing FAD-like genes, we recently demonstrated that the corresponding mRNAs were strongly induced in parsley cells upon treatment with the Pep25 elicitor (Kirsch et al, 1997). A closely related partial cDNA, previously isolated and designated ELI12 (Somssich et al, 1989), was found to share considerable sequence similarity with microsomal w-6 FADs and has been used as a probe to isolate a gene (FAD2 locus) encoding a microsomal 0-6 FAD gene from Arabidopsis thaliana (Kirsch et al, 1997).…”

“…Induction of this mRNA was equally rapid and transient in fungusinfected parsley leaves and resulted in the highly localized accumulation of 0-3 FAD mRNA at infection sites (Kirsch et al, 1997).…”