Differential Inhibition by Ferulic Acid of Nitrate and Ammonium Uptake in Zea mays L.

Abstract

The influence of the allelopathic compound ferulic acid (FA) on nitrogen uptake from solutions containing both N03-and NH4+ was examined in 8-day-old nitrogen-depleted com (Zea mays L.) seedlings. Concurrent effects on uptake of Clr and K+ also were assessed. The presence of 250 micromolar FA inhibited the initial (0-1 hours) rate of NO3-uptake and also prevented development of the NO3--inducible accelerated rate. The pattem of recovery when FA was removed was interpreted as indicating a rapid relief of FA-restricted N03-uptake activity, followed by a reinitiation of the induction of that activity. No inhibitiot of NO3-reduction was detected. Ammonium uptake was less sensitive than N03-uptake to inhibition by FA. An inhibition of Cl-uptake occurred as induction of the N03-transport system developed in the absence of FA. Alterations of Cl-uptake in the presence of FA were, therefore, a result of a beneficial effect, because NO3-uptake was restricted, and a direct inhibitory effect. The presence of FA increased the initial net K+ loss from the roots during exposure to the low K, ammonium nitrate uptake solution and delayed the recovery to positive net uptake, but it did not alter the general pattem of the response. The implications of the observations are discussed for growth of plants under natural conditions and cultural practices that foster periodic accumulation of allelopathic substances.A deleterious effect of the phenolic compound FA2 on the uptake of phosphorus and potassium has been observed frequently (6,7,13,21 Little is known about the effect of allelopathic compounds on nitrogen uptake. In addition to probable effects of limiting the total nitrogen taken up, the possibility exists for differential effects on NO3-and NH4' uptake. Moreover, the amount and ionic form of nitrogen are significant factors in determining the uptake of other ions such as potassium (23, 28), phosphate (25, 26), chloride (4, 11), and sulfate (2). For example, K+ uptake often is facilitated by NO3-(16) and inhibited by NH4' (27, 28), whereas Cl-influx is inhibited by ambient NO3-and by the sum of NO3-and Cl-in the tissue (4, 1 1). It is possible, therefore, that effects exerted by allelochemicals on nitrogen uptake may alter the uptake of other ions. Accordingly, the objective of this investigation was to ascertain the inhibitory effect ofa typical phenolic compound, FA, on nitrogen uptake and on concurrent uptake of K+ and C1-. MATERIALS AND METHODS Plant CultureAll experiments were conducted with intact nitrogen-deprived, 8-d-old maize (Zea mays L., Pioneer Hybrid 3369a) seedlings. At this stage of development, the endosperm is largely depleted of nitrogen reserves. Seeds were germinated in darkness at 30C and 98% RH in paper rolls moistened with 0.1 mm CaSO4. After 78 to 82 h, all roots except the primary root were excised. Primary roots of four seedlings (one culture) were threaded through separate holes in the bottom of polyethylene cups (2.5 cm high and 3.5 cm diameter). The seeds within the cups were packed with c...

Allelochemical effects on net nitrate uptake and plasma membrane H⁺-ATPase activity in maize seedlings

“…The simultaneous presence of a methyl and a hydroxyl group in ferulic acid reduced the negative effect on NNUR in comparison with trans-cinnamic and p-coumaric acids. These results contrast with Bergmark et al (1992) and Booker et al (1992) who reported the strong inhibition of NNUR by ferulic acid. The contrast with Bergmark's results can be explained by the different species and root size.…”

“…The cHATS is constitutively expressed in nitrate-starved roots and exhibits a constant nitrate uptake rate, while the iHATS, the dynamic component, is induced by nitrate reaching a maximum uptake rate (full induction) after several hours of exposure to the anion (Aslam et al 1992) and it is feedback-regulated by downstream of N metabolites such as glutamate, glutamine and arginine (Forde 2000, Li et al 2009. Previous studies have shown that ferulic acid and coumarin do not affect cHATS but interfere with iHATS activity (Bergmark et al 1992, Abenavoli et al 2001. In particular, 250 µM ferulic acid prevented development of the NO 3 -inducible accelerated uptake rate in maize roots, while 100 µM coumarin stimulated the net nitrate uptake upon full induction in wheat roots (Abenavoli et al 2001).…”

Consumption of ferulic and p-hydroxybenzoic acids by soybean root tips

“…In soils, these compounds were found at concentrations between 0.01 and 0.1 mM (Whitehead, 1964;Whitehead et al 1982). Exposure of plant roots to phenolic acids, at different concentrations, reduces water utilization (Hollapa and Blum, 1991), inhibits foliar expansion and root elongation (Blum and Rebbeck, 1989), reduces rates of photosynthesis (Patterson, 1981) and inhibits nutrient uptake (Lyu and Blum, 1990;Bergmark et al 1992). Although information concerning the effects of ferulic and p-hydroxybenzoic acids on physiological responses of a variety of species is extensive, little attention has been given to the absorption of these compounds by roots.…”

Ferulic acid depletion by cultured soybean seedlings under action of glucose and methionine

“…Allelochemicals active against higher plants are typically characterized as suppressing seed germination, causing injury to root growth, or inhibiting seedling growth. Furthermore, they alter water utilization and mineral uptake (Lyu and Blum, 1990;Hollapa and Blum, 1991;Bergmark et al 1992), chlorophyll content and photosynthesis rates (Mersie and Singh, 1993), foliar expansion (Blum and Rebbeck, 1989), cell morphology (Liu and Lovett, 1993) and protein synthesis (Baziramakenga et al 1997) among countless other actions. Although physiological actions have been documented extensively in several species, limited attention has been given to evaluate how other organic molecules distributed in soils may alter phenolic acid toxicity.…”