Location: Cereal Crops Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1 – Evaluate the biotic and abiotic factors that influence avenanthramide biosynthesis in oat. Objective 2 – Investigate the in vitro modification of oat avenanthramides mediated by mammalian metabolic pathways and their relation to human health benefits. Objective 3 – Investigate the physiological function of tocopherols and other phytochemicals in oat and barley.
1b. Approach (from AD-416):
Objective 1. Plant defense activators (PDA), agrichemicals that elicit a generalized defense response against pathogenic organisms, will be assessed to determine their efficacy in enhancing avenanthramide levels in the oat grain. Preliminary experiments have shown that benzothiadiazole (BTH) effectively up-regulates avenanthramide production in greenhouse experiments. These experiments will be expanded to include other PDAs and to evaluate their efficacy in field grown oats. The volatile organic compounds elicited by PDA treatment will be captured and analyzed by gas chromatography-mass spectrometry (GC-MS) to determine if any known volatile signaling molecules are elicited. Additionally, oat plants will be subjected to light intensity stress and leaf avenanthramide levels analyzed to determine if this abiotic factor affects avenanthramide production. Oat genomic DNA will be sequenced to determine the type of promoter regions present upstream of the coding region of the enzymes involved in avenanthramide production. Objective 2. Synthetic avenanthramides will be physiologically modified (glucuronidated) by incubation with rat liver extracts and with commercially available, cloned human enzymes. These, in turn, will be provide to scientists at the University of Minnesota School of Kinesiology (and others interested) for evaluation of their nutraceutal properties or use as high performance liquid chromatography (HPLC) standards. Objective 3. Leaf extracts of winter barley mapping populations will be analyzed by HPLC and fluorescence detection to determine if a relationship between tocochromanol production and winter hardiness exists. We will also use preparative scale HPLC with fluorescence detection to isolate fluorescent compounds from winter hardy oat root crowns for further chemical identification by nuclear magnetic resonance (NMR) and mass spectral analysis.
3. Progress Report:
Field trials with BTH. ARS Researchers at Madison, WI have found that benzothiadiazole (BTH), a commercially available plant defense activator, substantially up-regulates the production of avenanthramides in oat in greenhouse experiments. Field trials of benzothiadiazole (BTH) treatment have been initiated in Madison, WI These trials will attempt to determine if the greenhouse results can be replicated under field conditions. Thus far the oats have been planted and treated, and leaf and grain samples collected. Data are forthcoming. If successful these experiments will demonstrate the practical application of plant defense activators in enhancing avenanthramide production in the oat crop and a potential mechanism to protect the oat crop from damage by crown rust infection.