Molecular phenotyping of the pal1 and pal2 mutants of Arabidopsis thaliana reveals far-reaching consequences on phenylpropanoid, amino acid, and carbohydrate metabolism.
The first enzyme of the phenylpropanoid pathway, Phe ammonia-lyase (PAL), is encoded by four genes in Arabidopsis thaliana. Whereas PAL function is well established in various plants, an insight into the functional significance of individual gene family members is lacking. We show that in the absence of clear phenotypic alterations in the Arabidopsis pal1 and pal2 single mutants and with limited phenotypic alterations in the pal1 pal2 double mutant, significant modifications occur in the transcriptome and metabolome of the pal mutants. The disruption of PAL led to transcriptomic adaptation of components of the phenylpropanoid biosynthesis, carbohydrate metabolism, and amino acid metabolism, revealing complex interactions at the level of gene expression between these pathways. Corresponding biochemical changes included a decrease in the three major flavonol glycosides, glycosylated vanillic acid, scopolin, and two novel feruloyl malates coupled to coniferyl alcohol. Moreover, Phe overaccumulated in the double mutant, and the levels of many other amino acids were significantly imbalanced. The lignin content was significantly reduced, and the syringyl/guaiacyl ratio of lignin monomers had increased. Together, from the molecular phenotype, common and specific functions of PAL1 and PAL2 are delineated, and PAL1 is qualified as being more important for the generation of phenylpropanoids.
Rohde
Antje
A
Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, Ghent University, B-9052 Ghent, Belgium.
Morreel
Kris
K
Ralph
John
J
Goeminne
Geert
G
Hostyn
Vanessa
V
De Rycke
Riet
R
Kushnir
Sergej
S
Van Doorsselaere
Jan
J
Joseleau
Jean-Paul
JP
Vuylsteke
Marnik
M
Van Driessche
Gonzalez
G
Van Beeumen
Jozef
J
Messens
Eric
E
Boerjan
Wout
W
D000596:Amino Acids / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D017343:Genes, Plant; D009154:Mutation; D010641:Phenotype; D010666:Phenylpropionates / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000596:Amino Acids; D017931:DNA Primers; D010666:Phenylpropionates