ASSESSING GENOTYPIC SOFTNESS IN SINGLE WHEAT KERNELS USING STARCH GRANULE- ASSOCIATED FRIABILIN AS A BIOCHEMICAL MARKER

Authors: BETTGE AD - 5348-05-00; MORRIS CF - 5348-05-00; GREENBLATT GA - WASHINGTON STATE UNIV

Submitted to: Euphytica International Journal on Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Wheat kernel texture, along with protein content, primarily determines the suitability of wheat grain for use in a particular food product, and therefore, the wheat's direction in marketing channels. Wheat texture, or hardness, is genetically determined, but varies considerably due to environment. Current hardness testing methods require large amounts of wheat grain, provide only an average hardness value, are destructive and the results can vary considerably due to the growing environment. A method was developed to determine the genetic textural predisposition of single kernels of wheat using a reliable protein marker, friabiline, which is unaffected by environment. Friabilin is found abundantly on starch granules from soft wheat, in very low amounts on hard wheat starch granules and not at all on durum wheat starch granules. This method not only allows determination of hardness potential of single wheat kernels, but also allows unused portions of the kernel to be used for determination of high molecular weight glutenin subunit banding patterns, which have been shown to be correlated with performance of wheat flour in bakeries. Additionally the wheat embryo is not destroyed in this procedure and can be germinated and grown, with a considerable amount already known about its quality characteristics. This single kernel method can be used in early generations of wheat breeding programs where amounts of seed available for testing are quite limited. Knowledge of the quality potential of new wheat crosses at early generations would allow wheat breedeers to advance only the most promising lines, discarding undesirable lines and thereby conserving resources. Questions of whether wheat classes had been mixed in marketing channels could also be answered with this technique.

Technical Abstract: Wheat kernel texture is traditionally determined by several methods, including Particle Size Index, grinding time and resistance, and near infrared reflectance spectroscopy. The results derived from these methods are influenced by the environment and require bulk grain in excess of that available in early generations of wheat breeding programs. An objective method for the determination of genotypic texture of single kernels of wheat was developed using a 15 kDa protein (friabilin). Friabilin is a biochemical marker found on water-washed starch granules and is perfectly correlated with grain softness. The technique presented here uses only a portion of the endosperm. Unused portions can be used for high molecular weight (HMW) glutenin subunit characteriazation and the excised germ portion of the kernel can be germinated to propagate the plant. Consequently, use of single kernel analyses can facilitate screening of new wcrosses at an early generation for endosperm textural predisposition and potential functional quality as defined by HMW glutenin subunits, thereby resulting in identification of promising lines and conserving resources otherwise spent in advancing undesirable lines.