Growth response of maize seed-borne fungi to cereal phenolic acid mixtures

Phenolic acids (PAs) are potential antifungal agents of stored grain cereals. Previous studies have mostly focused on the action of single compounds, consequently providing limited information on their effect as mixtures. We tested the hypothesis that higher phytochemical diversity and concentration of phenolic acids provide better defense against pathogenic fungi of cereals. Five maize seed-borne fungi with different degrees of specialization as cereal pathogens were exposed in vitro to five phenolic acids found in cereal grains either alone or in combinations. We detected that the inhibitory effect of PAs depended on their concentration and the fungus specialization, but the tested hypothesis was not functional for any plant-fungal species relationship. Moreover, various PAs or PAs-mixtures were almost equally inhibitory against the fungal species. We also found that phytochemical diversity had a differential effect on the phytopathogens according to their degree of specialization. Thus, a high phytochemical diversity in high concentration would protect a plant against a fungal community, but not necessarily against a single-fungus species.