15th International Conference on Arabidopsis Research - TAIR

T07-015
Chemical Analysis of Arabidopsis Mutants in the
Phenylpropanoid Pathway
Abdelali Hannoufa(1), Ulrike Schäfer(1), Gordon Gropp(1), Delwin Epp(1)
1-Molecular Genetics Section, Agriculture and Agri-Food Canada, Saskatoon Research Centre,
107 Science Place, Saskatoon, SK, Canada S7N 0X2
The identification of rate limiting steps in metabolic pathways is a prerequisite
for designing strategies to manipulate plant metabolism through genetic
engineering. To identify target genes for engineering the phenylpropanoid
pathway, we carried out chemical analysis on a collection of Arabidopsis
mutant lines with knockouts in genes involved in the biosynthesis pathway of
sinapoylcholine (sinapine). These mutants were obtained either by direct acquisition
from TAIR, i.e. SALK lines, or by screening Agriculture and Agri-Food
Canada’s Arabidopsis knockout population.
Chemical analysis carried out on seeds of wild type and homozygous
mutant lines revealed that the main storage form of phenolics in the seed is
sinapine, which represents over 50% of total extracted phenolics. Knockouts
in phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H)
and coumarate 3-hydroxylase (C3H) genes had no detectable effect on the
level of sinapine, but caused the accumulation of some other intermediate
phenolic compounds. On the other hand, knockouts in the caffeic acid O-methyltransferase
(COMT), ferulic acid hydroxylase (FAH) and sinapoylglucose:
choline sinapoyltransferase (SCT) genes resulted in significant reduction in
sinapine content. Reduction in the sinapine content of these three knockout
mutants also resulted in the accumulation of some intermediate phenolic
compounds, such as ferulic acid and sinapoylglucose. Unlike the COMT and
SCT mutants, low sinapine accumulation in the FAH mutant (