title: L-DOPA increases lignification associated with Glycine max root growth-inhibition.
abstract: L-3,4-dihydroxyphenylalanine (L: -DOPA), an allelochemical exuded from the roots of velvet bean [Mucuna pruriens (L.) DC. var. utilis], presents a highly inhibitory action to plant growth. The effects of L-DOPA on phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and peroxidase (POD, EC 1.11.1.7) activities, and phenolic compound and lignin content in soybean [Glycine max (L.) Merr.] roots were investigated to determine the possible phytotoxic mechanism. Three-day-old seedlings were cultivated in half-strength Hoagland nutrient solution (pH 6.0), without or with 0.1 to 1.0 mM L-DOPA in a growth chamber (25 degrees C, 12-hr light to 12-hr darkness photoperiod, irradiance of 280 micromol m-2 s-1) for 24 hr. In general, the length, fresh weight, and dry weight of the roots decreased, whereas PAL and POD activities and phenolic compound and lignin content increased after L-DOPA treatments. Results showed the susceptibility of soybean to L-DOPA and reinforce the role of this nonprotein amino acid as a strong allelochemical. The present findings also suggest that L-DOPA-induced inhibition in soybean roots may be because of a cell wall stiffening process related to the formation of cross-linking between cell wall polymers linked to lignin production.
authors.affiliation: Laboratory of Plant Biochemistry, Department of Biochemistry, University of Maringá, Av. Colombo, 5790, 87020-900, Maringá, PR, Brazil.
authors.forename: Anderson Ricardo
authors.initials: AR
authors.lastname: Soares
authors.forename: Maria de Lourdes Lucio
authors.initials: Mde L
authors.lastname: Ferrarese
authors.forename: Rita de Cássia
authors.initials: Rde C
authors.lastname: Siqueira
authors.forename: Franciele Mara Lucca Zanardo
authors.initials: FM
authors.lastname: Böhm
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Ferrarese-Filho
mesh_terms: D007980:Levodopa / Q000494:pharmacology*; D008031:Lignin / Q000378:metabolism*; D031299:Mucuna / Q000737:chemistry; D009195:Peroxidase / Q000187:drug effects / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000187:drug effects / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects* / Q000378:metabolism; D013025:Glycine max / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D010937:Plant Growth Regulators; D007980:Levodopa; D008031:Lignin; D009195:Peroxidase; D010650:Phenylalanine Ammonia-Lyase