ARS | Publication request: Avenanthramide biosynthesis in oat cultivars treated with systemic acquired resistance elicitors

Submitted to: Cereal Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 18, 2012
Publication Date: N/A

Interpretive Summary: Oats produce a group of phenolic antioxidants termed avenanthramides. These metabolites are, among food crops, unique to oats and have shown certain desirable nutritional characteristics such as inhibiting atherosclerotic plaque formation and reducing inflammation. There are currently a selection of agrichemicals termed “plant defense activators” (PDA) that stimulate disease resistance in plants. Previous experiments have show that one cultivar of oat, ‘Belle’, responded to treatment with Actigard (or BTH) by upregulating the production of avenanthramides in the vegetative tissue. These experiments demonstrate that oats are responsive to an additional PDA, namely 2,6- dichloroisonicotinic acid (INA) and that there are substantial differences in the magnitude and dynamics of various oat cultivars to treatment with these PDAs. Moreover, PDA treatment also appears to enhance the production of avenanthramides in the filling grain of mature plants. The impact is to (1) provide a tool for investigation of mechanisms regulating avenanthramide biosynthesis in whole oat plants, (2) illustrates the potential to increase the crown rust resistance in field grown oats and (3) provides an agronomic tool to increase the levels of avenanthramides in the oat crop.

Technical Abstract: The synthetic systemic acquired resistance elicitor benzothiadiazole (BTH) has been shown to elicit avenanthramide biosynthesis in the oat cultivar ‘Belle’. This report investigates the response of multiple oat cultivars to BTH as well as 2,6- dichloroisonicotinic acid (INA) at different growth stages. Oat seedlings (‘Gem’, ‘Kame’, and ‘Ogle’) were treated with 2,6- dichloroisonicotinic acid (INA) or benzothiadiazole (BTH) at the three leaf (Z13) stage and subsequently assessed for accumulation of avenanthramides and analyzed for the activities of hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroycinnamoyl transferase (HHT). In addition, four cultivars (‘Belle’, ‘Gem’, ‘Kame’, and ‘Ogle’) were treated at the Z43 stage with BTH. The results indicated that after 48 h avenanthramides accumulated to significantly higher levels in the oat leaves in response to both INA and BTH treatment and this response tended to be fairly long lasting (336 h or more). Both elicitors also raised the activities of HHT enzyme in seedling leaves after 48 h. Genotypic differences in the kinetics and quantitative response were also observed in both the seedlings and the mature plants. The magnitude of avenanthramide production in the leaves was somewhat higher in the more mature plants. Filling grain also showed higher levels of avenanthramides compared to the untreated controls.