**Session II -- Cereal Science, Whole Grain Foods and Processing --Talk:
Wise & Jackson**

**Factors Effecting Phytonutrient Biosynthesis in Oat**

Mitchell L. Wise^1,\*^ Eric Jackson^2^, and Douglas Doehlert ^3^

^1^USDA-ARS Cereal Crops Research Unit, 502 Walnut St. Madison, WI,
53726-2335

^2^USDA-ARS Small Grains and Potato Research Unit, 1691 S. 2700 W.
Aberdeen, ID 83210

^3^USDA-ARS Wheat Quality Laboratory, North Dakota State University,
Fargo, ND 58105

\*Corresponding author: Ph (608) 262-9242, e-mail: mlwise@wisc.edu

Numerous reports correlate oat consumption with lowered risk of
cardiovascular disease. Although much of this research has focused on
the role of soluble fiber, oat produces other phytonutrients having
beneficial physiological effects. These include avenanthramides,
tocopherols, and tocotrienols. Although avenanthramides were described
almost twenty years ago by F. William Collins, only recently has
substantial evidence surfaced that these metabolites provide health
benefits. One of these is to mitigate inflammatory responses in model
systems for atherosclerosis. They also appear to reduce oxidative damage
in exercise stressed rats.

The levels of avenanthramides found in oat grain are highly variable,
ranging from below 10 ppm up to 400 ppm or more. What factors mediate
these variations is poorly understood, although there are clear
genotypic and environmental relationships. Seedling studies show that
leaf tissues respond to crown rust infection or pathogen elicitors by
up-regulating avenanthramide biosynthesis. A limited number of field
studies have shown clear environmental effects on avenanthramide content
in oat leading to speculation that grain avenanthramide levels are
elevated in response to rust infection. This discussion will provide
clear evidence that such a relationship exist. Data from replicated
field trials evaluating eighteen oat cultivars in eastern North Dakota
will be presented. Two of the test environments suffered heavy rust
pressure, the other four did not. Avenanthramide content showed a
distinct correlation with the occurrence of rust, with levels from ten
to thirty times higher in the infected plants. Additionally, there
appears to be a strong genotypic influence on grain avenanthramide
production. Field tests in a crown rust free environment (Idaho) were
conducted to evaluate avenanthramide levels in seed of a recombinant
inbred line (RIL) population derived from a cross of the crown rust
susceptible parent 'Otana' and the resistant parent TAM O-405. Parents
and RILs were grown under an artificially produced crown rust epidemic
and under no disease pressure. In the disease free environment, one
fungicide application of Tilt~®~ was applied at the flag leaf stage.
Again, a correlation between rust infection and avenanthramide
production was observed. Interestingly, some of the RILs showed
extremely high avenanthramide levels, with or without rust infection.
These preliminary results suggest the possibility of breeding for higher
avenanthramide content in oat.

To study the factors affecting tocopherol levels in oat, α-tocotrienol,
α-tocopherol, and total tocopherol contents were measured in seed of the
Ogle/TAM O-301 RIL population from replicated Idaho field trials. Mean
levels of all three tocopherol measurements were higher from the
irrigated Aberdeen location than from the non-irrigated Tetonia
location. This data indicates that moisture content and soil nutrients
could directly affect whole grain tocopherol levels. Genetic analysis
detected one quantitative trait loci (QTL) with major effects and four
QTL with minor effects accounting for a majority of the α-tocotrienol
variation across all locations, while six QTL accounted for a majority
of the α-tocopherol variation. Only one QTL affecting total tocopherol
was detected apart from QTL affecting α-tocotrienol and α-tocopherol.
These results should facilitate the development of markers linked to key
genes affecting tocopherol production in oat whole grain, as well as,
the identification of the environment factors influencing these
important quality traits.