The effects of l-DOPA on root growth, lignification and enzyme activity in soybean seedlings

Autor: Victor Hugo Salvador, Maria de Lourdes Lucio Ferrarese, Anderson Ricardo Soares, Osvaldo Ferrarese-Filho, Rita de Cássia Siqueira-Soares
Rok vydání: 2012
Předmět:
Zdroj: Acta Physiologiae Plantarum. 34:1811-1817
ISSN: 1861-1664
0137-5881
Popis: In the present study, we investigated the effects of l-DOPA (l-3,4-dihydroxyphenylalanine), an allelochemical exuded from the velvetbean (Mucuna pruriens L DC. var. utilis), on the growth and cell viability of soybean (Glycine max L. Merrill) roots. We analyzed the effects of l-DOPA on phenylalanine ammonia lyase (PAL), cinnamyl-alcohol dehydrogenase (CAD) and cell wall-bound peroxidase (POD) activities as well as its effects on phenylalanine, tyrosine and lignin contents in the roots. 3-day-old seedlings were cultivated in half-strength Hoagland nutrient solution (pH 6.0), with or without 0.5 mM l-DOPA, in a growth chamber at 25 °C for 6, 12, 18 or 24 h with a day/night regime of 1:1, and a photon flux density of 280 μmol m−2 s−1. In general, the length, fresh weight and dry weight of the roots decreased followed by a significant loss of cell viability. Phenylalanine, tyrosine and lignin contents as well as PAL, CAD and cell wall-bound POD activities increased after l-DOPA treatment. These results reinforce the susceptibility of soybean to l-DOPA, which increases the enzyme activity in the phenylpropanoid pathway and, therefore, provides precursors for the polymerization of lignin. In brief, these findings suggest that the inhibition of soybean root growth induced by exogenously applied l-DOPA may be due to excessive production of lignin in the cell wall.
Databáze: OpenAIRE
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