Stress responses in alfalfa (Medicago sativa L.). XX. Transcriptional activation of phenlpropanoid pathway genes in elicitor-induced cell suspension cultures.
Nuclear transcript run-on analysis was used to investigate++ the relative transcription rates of genes encoding enzymes of isoflavonoid phytoalexin biosynthesis and related pathways in elicitor-treated alfalfa (Medicago sativa L.) cell suspension cultures. Genes encoding L-phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and chalcone reductase (CHR) were most rapidly activated, with increases in transcription measurable within 10-20 min after elicitation. Cinnamic acid 4-hydroxylase (C4H), chalcone isomerase (CHI), isoflavone reductase (IFR) and caffeic acid 3-0-methyltransferase (COMT) genes were also rapidly activated, but at a slower initial rate. Transcription of chalcone 2'-O-methyltransferase (CHOMT), and 1,3-beta-D-glucanase genes was less rapid, with lag periods of 60 and 30 min post-elicitation, respectively. Treatment of cells with a PAL inhibitor L-alpha-aminooxy-beta-phenylpropionic acid (AOPP) resulted in increased transcription of PAL, CHS and CHR, but reduced transcription of CHOMT, indicating a role for phenylpropanoid products as both negative and positive regulators of gene expression within the phenylpropanoid pathway.
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Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73402, USA.
Fahrendorf
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T
Ballance
G M
GM
Lamb
C J
CJ
Dixon
R A
RA
D002478:Cells, Cultured; D005419:Flavonoids / Q000096:biosynthesis / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D000455:Medicago sativa / Q000201:enzymology / Q000235:genetics*; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics; D010936:Plant Extracts / Q000096:biosynthesis; D012717:Sesquiterpenes; D013729:Terpenes; D015533:Transcriptional Activation; D000094162:Phytoalexins
D005419:Flavonoids; D010936:Plant Extracts; D012717:Sesquiterpenes; D013729:Terpenes; D010650:Phenylalanine Ammonia-Lyase; D000094162:Phytoalexins