Managing Phenol Contents in Crop Plants by Phytochemical Farming and Breeding—Visions and Constraints

Abstract

Two main fields of interest form the background of actual demand for optimized levels of phenolic compounds in crop plants. These are human health and plant resistance to pathogens and to biotic and abiotic stress factors. A survey of agricultural technologies influencing the biosynthesis and accumulation of phenolic compounds in crop plants is presented, including observations on the effects of light, temperature, mineral nutrition, water management, grafting, elevated atmospheric CO2, growth and differentiation of the plant and application of elicitors, stimulating agents and plant activators. The underlying mechanisms are discussed with respect to carbohydrate availability, trade-offs to competing demands as well as to regulatory elements. Outlines are given for genetic engineering and plant breeding. Constraints and possible physiological feedbacks are considered for successful and sustainable application of agricultural techniques with respect to management of plant phenol profiles and concentrations.

Oxidative discolouration in whole-head and cut lettuce: biochemical and environmental influences on a complex phenotype and potential breeding strategies to improve shelf-life

“…Water-deficit stress has also been shown to increase the concentration of certain phenolic compounds in lettuce, particularly chicoric acid (Oh et al 2010) and to cause the accumulation of antioxidant compounds (Sofo et al 2005;Oh et al 2010), which may potentially inhibit oxidation of phenolics and thus discolouration development. Whilst there is no evidence to specifically associate increased levels of chicoric acid with a reduction in the level of lettuce discolouration, the different pathways involved in phenylpropanoid metabolism are interlinked (Treutter 2010), consequently, the diversion of plant resources into one pathway (i.e. increasing production of chicoric acid) may result in a reduction of resources available for other branches, potentially leading to reduced levels of compounds which may be more directly involved in discolouration.…”

Analysis of selected primary metabolites and phenolic profile of ‘Golden Delicious’ apples from four production systems

“…They have been reported as naturally occurring antioxidants, contributing against oxidative damage caused by free radicals which influence many chronic human diseases [8]. Their content and profile in fruit is influenced by several factors, including climate [9], the effects of light [10], cultivars [11], temperature, mineral nutrition, water management, grafting, application of elicitors, stimulating agents, plant activators [12] and exposure to various kinds of stress [13]. Veberic et al established that organically grown apples exhibited a higher content of phenolic compounds in apple pulp compared with apples from integrated production [14].…”

Influence of foliar nutrients on phenol levels in leaves of Eugenia uniflora

“…In the majority of studies phenolic production decreases at high nitrogen availability and increases under nitrogen deficiency (Treutter, 2010). This trend was not followed by E. uniflora phenolics, which showed no correlation in their contents with nitrogen levels.…”

“…Moreover, it is known that Cu and Mn influence the activity of many cellular enzymes, such as phenylalanine ammonia-lyase (PAL) (Santiago et al, 2000;Kováčik & Klejdus, 2008;Treutter, 2010), peroxidases (Diaz et al, 2001, Lin et al, 2005, Gross, 2008Kováčik et al, 2009), laccases (Lin et al, 2005), and shikimate dehydrogenase (Diaz et al, 2001, Kováčik et al, 2009.…”