1. L-DOPA increases lignification associated with Glycine max root growth-inhibition.
- Author
-
Soares AR, Ferrarese Mde L, Siqueira Rde C, Böhm FM, and Ferrarese-Filho O
- Subjects
- Mucuna chemistry, Peroxidase drug effects, Peroxidase metabolism, Phenylalanine Ammonia-Lyase drug effects, Phenylalanine Ammonia-Lyase metabolism, Plant Roots metabolism, Glycine max growth & development, Glycine max metabolism, Levodopa pharmacology, Lignin metabolism, Plant Growth Regulators pharmacology, Plant Roots drug effects, Glycine max drug effects
- 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.
- Published
- 2007
- Full Text
- View/download PDF