Greater variability in starch properties is found in lower ploidy wheats than in com. hexaploid wheats.This paper reports on the starch properties and variability in granule bound starch synthase (GBSS) loci of 17 diploid (Aegilops tauschii) and 12 tetraploid (durums) potential progenitors of wheat, compared with 29 synthetic hexaploid wheats produced from such progenitors.Starch properties examined were granule size distribution, swelling power, amylose content, gelatinization and amylose-lipid dissociation properties.A PCR screening method was able to detect the presence or absence of each of the three GBSS genes.It also detected polymorphisms in eight diploids and nine hexaploids, all displaying the same 25 bases deletion in the D genome allele of GBSS.Two tetraploids and five hexaploids were null 4A for GBSS.There was little difference in the amylose contents and amylose-lipid dissociation peak temperatures of the synthetic hexaploids and the lower ploidy wheats.The synthetic hexaploids showed intermediate swelling power values with the durums giving the highest swelling powers.The durums also had higher B granule contents than the A. tauschii accessions, but not as high as the synthetics.However, the A. tauschii samples gave the highest gelatinization peak temperaturesThe presence of the null 4A mutation was pos. correlated with swelling power, amylose content and DSC measurements.The new smaller D genome allele of GBSS was associated with slightly higher swelling power.These results confirm the value of wheat progenitor lines as sources of new starch properties for hexaploid wheat.

2006-02-01·Journal of Near Infrared Spectroscopy

Application of near Infrared Reflectance Spectroscopy to a Durum Wheat Breeding Programme

作者: Sissons, Shaylene ; Osborne, Brian ; Sissons, Mike

The breeding of new cereal grain varieties requires methods that are rapid and preferably non-destructive, to assess the quality of grain in early generations. Near infrared (NIR) spectroscopy has great potential to meet these requirements for the durum wheat breeder. In this study, sample sets representing durum wheats from an Australian durum breeding programme were used to develop several NIR calibrations. Useful predictive calibrations from scanning whole grain samples were developed for hectolitre weight, semolina yield, semolina b* and hardness, in addition to highly accurate calibrations for protein and moisture. It was not possible to adequately predict dough properties and black point percentage from whole grain scanning. A useful calibration to measure semolina browning reaction, applicable to early generation screening, was also developed. These calibrations have been extensively validated using large independent sample sets.

2005-12-01·Journal of Near Infrared Spectroscopy

The Challenge of Single Estimates in near Infrared Calibration and Prediction: The Measurement of Durum Vitreousness Using Receival Instruments

作者: Ruggiero, K. ; Osborne, B.G. ; Wesley, I.J. ; Anderssen, R.S.

The development of a near infrared (NIR) calibration for the estimation of percentage hard vitreous kernel (%HVK) in whole durum at grain receival points has been driven by the needs of international trade. This application presented some special challenges due to the nature of the available reference data, which were obtained using the Farinator method. The Farinator (transverse grain cutter) method is subjective and is thus subject to large errors, leading to single estimates being very poor reference data. This problem can be overcome by making a number of replicate measurements and using the average of these as a more accurate estimate of the true value. However, this is at the expense of substantially increased analysis time, hence cost. In addition, the HVK methodology involves a grain by grain assessment in which each grain can have only one of two possible classifications, i.e. “vitreous” and “not fully vitreous”. A binomial test such as this introduces an additional complication arising from sampling error, thus making the accuracy of the method sensitive to the number of grains examined. The accuracy also varies across the range of %HVK values so that the greatest errors are observed in the middle of the range. Fortunately, however, the high end of the range corresponding to the lowest errors is also the most commercially relevant. This paper describes a procedure in which, by restricting the calibration range to the optimum for a binomial test, an NIR model suitable for use at receival points could be obtained. The compromise was to calibrate using single Farinator estimates on a large number of samples but to validate using average Farinator estimates on a small number of samples. The results have confirmed that the NIR model yields a more reliable estimate of the true value of %HVK than would a single Farinator estimate on which the calibration was based.

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