Journal of Food, Agriculture & Environment, Vol.14 (2), April 2016 59 www.world-food.net Journal of Food, Agriculture & Environment Vol.14 (2):59- 64. 2016 WFL Publisher Science and Technology Meri-Rastilantie 3 B, FI-00980 Helsinki, Finland e-mail: info@world-food.net Received 15 November 2015, accepted 23 March 2016. Comparison of total phenolic content and antioxidant capacity of mycorrhizal-colonized white, red and purple spring wheat (Triticum aestivum L.) genotypes Daishu Yi 1 , Timothy Schwinghamer 1 , Yolande Dalpé 2 , El-Sayed Abdel-Aal 3 , Jaswinder Singh 1 , Xuelian Wang 2 and Shahrokh Khanizadeh 2 * 1 Department of Plant Science, McGill University, 21111 Lakeshore Road, Sainte-Anne-De-Bellevue, Quebec, Canada, H9X 3V9. 2 Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, K.W. Neatby Building, 960 Carling Avenue, Ottawa, Ontario, Canada, K1A 0C6 . 3 Guelph Research and Development Centre, Agriculture and Agri-Food Canada, 93 Stone Road West, Guelph, Ontario, Canada, N1G 5C9. *e-mail: shahrokh.khanizadeh@agr.gc.ca Abstract Wheat (Triticum aestivum L.) is one of the world’s most valuable crops, not only as a diet component but also as a source of dietary antioxidants. It is well known that wheat inoculated with mycorrhizal strains usually has a higher yield and stronger tolerance to stresses. However, information on the effect of mycorrhizal inoculation on the antioxidant capacity of wheat grains is scarce. The objective of this study was therefore to investigate and compare the total phenolic content (TPC) and DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging capacity of grains from four selected spring wheat varieties under colonization by four different mycorrhizal strains. Data were analyzed using PROC GLIMMIX (Generalized Linear Mixed Models) of the SAS software package. The results demonstrated that the coloured wheat, 13NQW1265, had the strongest DPPH scavenging capacity and the highest TPC in grains among all selected wheat genotypes, whereas the wheat variety Snowbird had a lower antioxidant capacity. A comparison between wheat colonized by mycorrhizal strains and non-inoculated wheat controls illustrated that the application of mycorrhizae had no significant effects on TPC in most wheat varieties; the exceptions were FL62R1 wheat inoculated with the commercial product Myke (Rhizophagus irregularis), which unexpectedly showed a negative effect, and 13NQW1265 wheat inoculated with Funneliformis mosseae, which increased TPC. As expected, a significant positive correlation was found between DPPH scavenging capacity and TPC, the main contributor to antioxidant capacity. The results suggest that mycorrhizal colonization could increase antioxidant compounds in wheat subject to wheat variety and mycorrhizal strain. Key words: Arbuscular mycorrhizae (AM), wheat (spring), grain, purple wheat, blue wheat, total phenolic content (TPC), DPPH radical scavenging capacity, antioxidant. Introduction The field of free radical chemistry and antioxidants has been attracting increasing attention recently. Most free radicals are chemically reactive atoms or molecules that are derived either from endogenous physiological and biochemical reactions, such as immune reactions, pathological changes to tissues, and aging, or from exogenous stimuli, including environmental pollution, drug intake, and improper cooking 1, 2 . Redundancy of free radicals leads to oxidative stress and causes damage to important biological molecules, including proteins, nucleotides, and lipids 3 . This damage results in pathological changes and chronic diseases 1, 2, 4 . Antioxidants, however, are molecules that can stabilize free radicals by providing electrons to neutralize the unpaired electrons of free radicals and thus decrease the risks of free-radical-induced cell damage. There are four levels of antioxidant defense actions 5 . First, there are antioxidants which could prevent the generation of free radicals from the very beginning. Once free radicals have already formed, the second defense system is activated in order to inactivate the free radicals and prevent further free-radical damage by either inhibiting initiation or breaking the elongation of reaction chains. Vitamin E is one of the most well-known endogenous radical-scavenging antioxidants. If free radicals have already caused structural damage to functional molecules such as proteins and nucleotides, then the third level of defense comes into play— the removal of oxidized molecules in a timely manner to prevent the overaccumulation of detrimental free radicals in living cells. The final level of defense is the generation and transport of antioxidants to functional sites under signal stimulation from the formation and reaction of free radicals 1, 5 . Some antioxidants are formed endogenously as the products of normal metabolic processes, as reported for ubiquinol and alpha-tocopheryl hydroquinone by Shi et al. 6 . However, a large number of antioxidants have to be taken in from exogenous sources, either because those antioxidants cannot be formed in the body, such as vitamin C, or because the amount generated in the body cannot meet the demand 7 . Synthetic and natural antioxidants are the two major groups of antioxidants that have been studied and applied in the fields of foods and medicine during the past several decades 1, 8 . However, increasing evidences have shown that