L-DOPA increases lignification associated with Glycine max root growth-inhibition.
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.
Soares
Anderson Ricardo
AR
Laboratory of Plant Biochemistry, Department of Biochemistry, University of Maringá, Av. Colombo, 5790, 87020-900, Maringá, PR, Brazil.
Ferrarese
Maria de Lourdes Lucio
Mde L
Siqueira
Rita de Cássia
Rde C
Böhm
Franciele Mara Lucca Zanardo
FM
Ferrarese-Filho
Osvaldo
O
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
D010937:Plant Growth Regulators; D007980:Levodopa; D008031:Lignin; D009195:Peroxidase; D010650:Phenylalanine Ammonia-Lyase