Allelopathy phenolic acids

Several general characteristics of the results compiled in Table I are worthy of mention. Compared to the variety of chemicals postulated to be involved in allelopathy (1), few specific compounds have been tested for inhibition of mineral absorption. The most extensively studied compounds are the phenolic acids, probably because of their being ubiquitously found in nature (1). Also, several flavonoids are inhibitory to mineral absorption (Table I). Both of these groups of compounds are often cited as being responsible for allelopathic interactions between plants. 

Phenolic acids can be allelopathic but their presence in soil is ephemeral due to rapid degradation and/or sorption by soil particles (Inderjit 2004). Sorption of benzoic acid onto soil particles increased with concentration and it may explain the reason for the limited allelopathic effect of benzoic acid at concentrations often recorded in natural soil (Inderjit 2004). Microorganisms help to generate allelochemicals, but they may also modify toxic compounds into nontoxic compounds (Khanh et al. 2005). Allelochemicals are changed in composition and quantity during the residue decomposition. Allelopathy plays an important function in nutrient recycling (Rice 1984). 

Phenolic acids are often found in plant tissue, and have been implicated in many cases of allelopathy (4). Figure 6 shows a separation of three free phenolic acids and Figure 7 shows mass spectra obtained from these compounds. These spectra give both molecular weight and structural information. Phenolic acids can easily be thermally decarboxylated. The height of the molecular ion peak varies owing to ion source temperature. The variation depends also to some extent on the composition of the LC eluent, and this will be further examined. 

Several phenolic acids and many nonspecific allelopathic conditions have been shown to alter the mineral content of plants, and certainly phenolic allelochemicals may perturb cellular functions in a number of ways that are of importance to plant nutrition (34,35). However, raising fertility does not always suppress allelopathic inhibition, and the interrelationships between these two factors are still not clear. Bhowmik and Doll (36) showed that allelopathic inhibition of corn and soybeans by residues of five annual weeds was not alleviated by supplemental nitrogen or phosphorus. Similarly, an increase in fertilizer did not overcome inhibition of corn by quackgrass or circumvent the autotoxicity of berseem clover Trifolivm alexandrium L.) (37,38). Even when raising nutrient levels releases Inhibition, it does not mean that allelopathy was inoperative under the original conditions. These instances simply illustrate the importance of the Interaction of the two stress conditions. 

Two cases will be presented to illustrate the difficulty in establishing allelopathy and in linking the agent to poor crop growth. Specifically, the role of phenolic acids and the role of toxin-producing pseudomonads colonizing wheat roots will be examined. 

Blum, U., Austin, M. F. and Shafer, S. R., 1999. The Fate and effects of phenolic acids in a plant-microbial-soil model system. In Macias, F. A., Galindo, J. C. G., Molinillo, and J. M. G., Cutler, H. G. (Eds.), Recent Advances on Allelopathy a Science for the Future. Cadiz University Press, Cadiz, Spain, 159-166... 

Dalton, B. R., 1999. The occurrence and behavior of plant phenolic acids in soil environments and their potential involvement in allelochemical interference interactions Methodological limitations in establishing conclusive proof of allelopathy. In Inderjit, Dakshini, K. M. M., and Foy, C. L., (Eds.), Principles and Practices in Plant Ecology Allelochemical Interactions, CRC Press, Boca Raton, FL, 57-74... 

Scopoletin is purported as the most widely distributed coumarin in higher plants, and scopoletin, umbelliferone, and esculetin are the ones most frequently linked to allelopathy. Given their phenylpropane origin, it is not surprising that these simple coumarins have many actions in common with the cinnamic acids. One variance is that coumarin and scopoletin have been reported to decrease mitosis,2 whereas at least at concentrations that correlate with growth inhibition, the phenolic acids do not appear to affect cell division. 

This has been referred to as soil sickness, or a sod-bound condition for grasses. Often, the cause is unknown, but the problem for several legumes may be due to allelopathy. In soil sickness of red clover pfiatzyiiz L.), isoflavonoid and phenolic acid... 

Boufalis, A., Pellissier, F., Trosset, L. 1994. Responses of mycorrhizal ftinhi to allelopathy Cenococcum geophilum and Laccaria laccata growth with phenolic acids. Acta Biol. Gall. 141 547-550. 

Phenolic acids are plant metabolites widely spread throughout the plant kingdom. Recent interest in phenolic acids stems from the potential protection they offer against oxidative damage diseases (e.g., coronary heart disease, stroke, and cancers) when consumed in fruits and vegetables. This chapter discusses the functicai of plant phenolic acids associated with diverse roles, including nutrient uptake, protein synthesis, photosynthesis, and allelopathy. It also provides an update of the... 

Although a great deal is still unknown regarding the roles of phenolic acids in plants, they have been connected with diverse functimis, including nutrient uptake, protein synthesis, enzyme activity, photosynthesis, stmctural components, and allelopathy [17]. 

Blum U (2007) Can data derived from field and laboratory bioassays establish the existence of aUelopathic interactions in nature In Fujii Y, Hiradate S (eds) Allelopathy new concepts and methodology. Science Pubhshers, Enfield, NH, pp 31-38 Blum U, Austin MF, Shafer SR (1999a) The fates and effects of phenolic acids in a plant-microbe-soil model system. In Macias FA, Galindo JCG, Mohnillo JMG, Cutler HG (eds) Recent advances in allelopathy I. A science for the future. Cadiz University Press, Puerto Real, pp 159-166... 

Indeijit, Streibig JC, Olofsdotter M (2002) Joint action of phenolic acids mixtures and its significance in aUelopathy research. Physiol Plant 114 422 28 Indeijit, Weston LA (2000) Are laboratory bioassays for allelopathy suitable for prediction of field responses J Chem Ecol 26 2111-2118... 

Niemeyer HM, Pesel ES, Capaja SV, Bravo HR, Franke S, Francke W (1989) Changes in hydroxamic acid levels of wheat plants induced by aphid feeding. Phytochemistry 28 447-449 Nilsson MC (1994) Separation of allelopathy and resource competition by the boreal dwarf shrub Empetrum hermaphwditum Hagerap. Oecologia 98 1-7 Ohno T (2001) Oxidation of phenolic acid derivatives by soil and its relevance to allelopathic activity. J Environ Qual 30 1631-1635... 

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