Wheat cultivar identification

MG Scanlon, HD Sapirstein, W Bushuk. Evaluation of the precision of high-performance liquid chromatography for wheat cultivar identification. Cereal Chem 66 112-116, 1989. 

High resolution two-dimensional electrophoresis allows hundreds of proteins to be separated and characterized in submilligram samples of complex protein mixtures. Applications of this method to the analysis of agriculturally important products, including milk, meat, and wheat are reviewed. In a model study we analyzed 100 individual kernels of the wheat cultivar Newton (Triticum aestivum L.) for electrophoretic variants. One variant protein was found in 47 kernels, while three variant proteins occurred together in two of the kernels. The implications of two-dimensional electrophoresis for cultivar identification and the problem of relating electrophoretic protein variants to genetic variants are discussed. 

Another major use of computers for HPLC data should be varietal identification (see later). Qualitatively, cereal storage proteins vary little within genotypes but significantly among different varieties, so they provide characteristic fingerprints. Varietal identification can be automated by computer comparisons with stored standard data. Scanlon et al. [80] showed that normalization of peak retention times provided sufficient precision for cultivar identification. Resulting data based on peak heights and times could be used in an automated library search to identify wheat varieties [81]. 

Hay and Sutton [145] first used RP-HPLC of prolamins to identify rye cultivars. Kubiczek et al. [120] subsequently examined this problem, made more difficult by ryels outcrossing nature and the heterogeneity of many established cultivars. Procedures were optimized for isolation and RP-HPLC of rye prolamins (secalins), extended to the intergeneric wheat-rye cross tricicale, and used for cultivar identification. These studies are reviewed by Kubiczek et al. [122]. 

Zhu, D. et al (2012) Identification of wheat cultivars based on the hyperspectral image of single seed. 

Most publications dealing with HPLC of cereals report on wheat. However, the results obtained for wheat are not necessarily valid for other cereals. As with wheat, research on nonwheat cereals usually deals with identification of varieties or cultivars and the evaluation of processing quality of the different varieties. 

Identification of oat (Avena) cultivars by HPLC was first reported by Lookhart and coworkers (153-155) in combined electrophoresis/HPLC experiments. The HPLC technique used was a modification of the procedure described by Bietz (137) for wheat. Generally, the prolamin fraction, i.e., the alcohol-soluble fraction, of oat species generates complex polyacrylamide gel-electrophoresis (PAGE) and RP-HPLC patterns, with increasing complexity as ploidy of the selections increased. Readily (visible) identification of the cultivars was possible only when PAGE and RP-HPLC results were combined. An HPLC procedure for the characterization of the major oat protein fractions was developed by Lapvetelainen et al. (156). Salt-soluble, alcohol-soluble, and alkali-soluble protein fractions were extracted with 0.1 M NaCl, 52% ethanol, and 1% SDS in 0.05 M borate (pH 10), respectively. For the five cultivars examined, RP-HPLC separations of salt- and alkali-soluble proteins were very similar, whereas the prolamin fraction enabled culti-var differentiation, except for very closely related cultivars. 

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