The inheritance and genetic expression of low molecular weight glutenin subunits in South African wheat cultivars

[摘要] English: 1. The aim of this study was to identify:a) The HMW glutenin subunit composition in South African bread and durumwheats.b) The effectiveness of LMW glutenins for the identification of bread and durumwheat varieties.c) Different classes of LMW glutenins.d) The differences in the band intensities of the different classes.e) The correlations between the certain combinations.f) The genetic distances between cultivars in bread and durum varieties.g) A new LMW glutenin nomenclature system that can help to distinguish betweenbread wheat cultivars.2. The cultivars were screened in a gliadin-free background using a simplified onedimensionalprocedure of Singh et al (1991). The HMWand LMW glutenins wererun on a single gel.3. The results were as follows:a) Many cultivars had the same HMW banding combinations in bread and durumwheats. It was therefore not possible to use HMW glutenins to distinguishbetween cultivars.b) The LMW glutenins were, however, very effective to distinguish betweencultivars. It was also possible to distinguish between cultivars with a closegenetic relationship and between near isogenic lines.c) Thirty-nine different classes of LMW glutenins were determined with the help ofthe standard deviations of different cultivars.d) It was possible to assign different band intensities to different classes. Someclasses contained light bands, while other contained dark bands. There werealso bands of medium intensity. In some classes light and dark bands occured inthe replications of the same cultivar.e) Correlations were found between certain combinations.f) The genetic distances between cultivars showed that there are genetic variationbetween durum wheat varieties, but that some bread wheat varieties are veryclosely related.g) A new nomenclature system was identified and this proved to be sufficient todistinguish between the different cultivars.4. The conclusions of this study are:a) The HMW glutenins must not be used for cultivar identification in South Africa. Itis only reliable to determine seed purity before commercialising new varieties.b) The LMW glutenins are very effective to distinguish between cultivars.c) The new nomenclature system is very effective for cultivar identification. Itexplains more of the variation between cultivars than the nomenclature system ofGupta and Shepherd (1990).d) Using this system, genetic markers must be identified for bread-making quality. Itmust also be tested if certain bands alone are responsible for bread-makingquality and if combinations of bands determine a good bread wheat cultivar.e) The influence on quality of the intensities of bands in the different classes mustalso be tested.

[发布机构] University of the Free State