Cinnamic acid increases lignin production and inhibits soybean root growth.
Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA) oxidase and cinnamate 4-hydroxylase (C4H) activities and lignin monomer composition in soybean (Glycine max) roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical increased the total lignin content, thus altering the sum and ratios of the p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) lignin monomers. When applied alone or with cinnamic acid, piperonylic acid (PIP, a quasi-irreversible inhibitor of C4H) reduced C4H activity, lignin and the H, G, S monomer content compared to the cinnamic acid treatment. Taken together, these results indicate that exogenously applied cinnamic acid can be channeled into the phenylpropanoid pathway via the C4H reaction, resulting in an increase in H lignin. In conjunction with enhanced IAA oxidase activity, these metabolic responses lead to the stiffening of the cell wall and are followed by a reduction in soybean root growth.
Laboratory of Plant Biochemistry, University of Maringá, Maringá, Paraná, Brazil.
Victor Hugo
VH
Salvador
Rogério Barbosa
RB
Lima
Wanderley Dantas
WD
dos Santos
Anderson Ricardo
AR
Soares
Paulo Alfredo Feitoza
PA
Böhm
Rogério
R
Marchiosi
Maria de Lourdes Lucio
Mde L
Ferrarese
Osvaldo
O
Ferrarese-Filho
D001565:Benzoates / Q000494:pharmacology; D018533:Biomass; D002934:Cinnamates / Q000494:pharmacology*; D008031:Lignin / Q000096:biosynthesis* / Q000737:chemistry; D010544:Peroxidases / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D013025:Glycine max / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D050564:Trans-Cinnamate 4-Monooxygenase / Q000378:metabolism
D001565:Benzoates; D002934:Cinnamates; C029010:cinnamic acid; D008031:Lignin; C027929:indoleacetic acid oxidase; D010544:Peroxidases; D050564:Trans-Cinnamate 4-Monooxygenase; C005455:piperonylic acid