Effects of Foliar Application of Elicitors on Red Clover Isoflavone Content

Abstract

Red clover (Trifolium pratense L.) contains high concentrations of isoflavones, compounds that have received much interest lately due to their presumed benefits for human health. In this experiment we tested the possibility to induce isoflavone production in the foliage of two greenhouse-grown red clover cultivars (ÔAzurÕ and ÔStartÕ) through the application of elicitor compounds. Foliar applications of different concentrations of acetic acid (50, 100, 250 and 500 mm), yeast extract (1, 2, 3 and 4 g l )1 ), and chitosan (125, 250, 500, and 1000 mg l )1 ) were carried out on plants at the late vegetative stage, which were harvested 2 or 8 days after spraying. Concentrations of genistein, daidzein, formononetin and biochanin A were determined by high performance liquid chromatography. The two cultivars differed in isoflavone concentrations, ÔAzurÕ having on average 36 % higher biochanin A, formononetin and total isoflavone concentrations than ÔStartÕ (P < 0.05). A cultivar · sampling date interaction (P < 0.1) reflected a 20 % increase over time in total isoflavone concentration with ÔAzurÕ, which was not observed with ÔStartÕ. Effects of elicitors were limited, contrasts indicating overall, 12, 14 and 15 % greater total isoflavone concentration in yeast extract (P < 0.1), chitosan (P < 0.05) and acetic acid (P < 0.05)-treated plants, respectively, than in untreated control plants. There were few differences between the various elicitors and none between concentrations of each elicitor.

Influence of the Application of Three Different Elicitors on Soybean Plants on the Concentrations of Several Isoflavones in Soybean Seeds

“…It has been shown that the concentration of specific elicitors has variable effects on isoflavones in different plant species. The responses of soybean and L. luteus were highly concentration dependent (10,13), but the concentration of elicitors had little effect on red clover (Trifolium pratense L.) (27). It has been suggested that multiple applications of elicitor may be more efficient in enhancing the plant defense response and in simulating isoflavone systhesis (27).…”

“…The responses of soybean and L. luteus were highly concentration dependent (10,13), but the concentration of elicitors had little effect on red clover (Trifolium pratense L.) (27). It has been suggested that multiple applications of elicitor may be more efficient in enhancing the plant defense response and in simulating isoflavone systhesis (27). Like elicitor type and concentration, application time had a significant effect on glycitein and aglycone content but not on other isoflavone components.…”

Elicitation of Pharmacologically Active Substances in an Intact Medical Plant

“…Merr.) and red clover (Trifolium pratense L.) , as well as phenolics in black chokeberry [Aronia melanocarpa (Michx) Elliot] , , black currant (Ribes nigrum L.) , nettle (Urtica dioica L.), dandelion (Taraxacum officinale), and purple coneflower (Echinacea purpurea L. Moench.)…”