Soybean (Glycine max) root lignification induced by ferulic acid. The possible mode of action.

Ferulic acid, in the form of feruloyl CoA, occupies a central position as an intermediate in the phenylpropanoid pathway. Due to the allelopathic function, its effects were tested on root growth, H(2)O(2) and lignin contents, and activities of cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195) and peroxidase (POD, EC 1.11.1.7) from soybean (Glycine max (L.) Merr.) root seedlings. Three-day-old seedlings were cultivated in half-strength Hoagland's solution (pH 6.0), with or without 1.0 mM ferulic acid in a growth chamber (25 degrees C, 12/12 hr light/dark photoperiod, irradiance of 280 micromol m(-2) s(-1)) for 24 or 48 hr. Exogenously supplied ferulic acid induced premature cessation of root growth, with disintegration of the root cap, compression of cells in the quiescent center, increase of the vascular cylinder diameter, and earlier lignification of the metaxylem. Moreover, the allelochemical decreased CAD activity and H(2)O(2) level and increased the anionic isoform PODa5 activity and lignin content. The lignin monomer composition of ferulic acid-exposed roots revealed a significant increase of guaiacyl (G) units. When applied jointly with piperonylic acid (an inhibitor of the cinnamate 4-hydroxylase, C4H), ferulic acid increased lignin content. By contrast, the application of 3,4-(methylenedioxy) cinnamic acid (an inhibitor of the 4-coumarate:CoA ligase, 4CL) with ferulic acid did not. Taken together, these results suggest that ferulic acid may be channeled into the phenylpropanoid pathway (by the 4CL reaction) and, further, may increase the lignin monomer amount solidifying the cell wall and restricting the root growth.

Effects of fatty acids on carbohydrates and lipids of canola seeds during germination

The present work was carried out to investigate the effects of caprylic acid (C8) and oleic acid (C18) on carbohydrates and lipids during canola seed germination. The results showed that oleic acid influence carbohydrate concentration but did not influence lipid concentration. Significant results were found with caprylic acid that affected carbohydrates and lipids in cotyledons after three-day germination.

O presente trabalho foi realizado com o objetivo de investigar os efeitos dos ácidos caprílico (C8) oleico (C18) sobre carboidratos e lipídeos durante a germinação de sementes de canola. Os resultados mostraram que ácido oleico influencia a concentração de carboidratos mas não altera a concentração de lipídeos. Resultados significativos foram encontrados com ácido caprílico que afetou tanto carboidratos como lipídeos, nos cotilédones, após três dias de germinação.

Efeitos de compostos fenólicos sobre a atividade da urease de soja / Effects of phenolics compounds on soybean urease activity

Allelopathy is defined as any direct or indirect harmful effect of one plant (including microorganisms) on another through the production of chemical compounds that escape into the environment. The allelochemicals produced by microorganisms or higher plants include p-coumaric and ferulic acids: these phenolic compounds were found in soils at concentration between 0,01 mM and 0,1mM. Soybean urease (E.C.3.5.1.5) catalyzes the hydrolysis of urea, thus producing carbon dioxide and ammonia which are important for plant growth. This article analyzes a probable relation between allelopathic agents and enzymatic activity of urease. The results show that p-coumaric acids is an inhibitor of urease at high concentrations (10mM), while ferulic acid inhibits the enzyme at extremely low concentrations (10-7mM)