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

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Date
1999-11
Authors
Maartens, Hilke
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Publisher
University of the Free State
Abstract
English: 1. The aim of this study was to identify: a) The HMW glutenin subunit composition in South African bread and durum wheats. b) The effectiveness of LMW glutenins for the identification of bread and durum wheat 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 between bread wheat cultivars. 2. The cultivars were screened in a gliadin-free background using a simplified onedimensional procedure of Singh et al (1991). The HMWand LMW glutenins were run on a single gel. 3. The results were as follows: a) Many cultivars had the same HMW banding combinations in bread and durum wheats. It was therefore not possible to use HMW glutenins to distinguish between cultivars. b) The LMW glutenins were, however, very effective to distinguish between cultivars. It was also possible to distinguish between cultivars with a close genetic relationship and between near isogenic lines. c) Thirty-nine different classes of LMW glutenins were determined with the help of the standard deviations of different cultivars. d) It was possible to assign different band intensities to different classes. Some classes contained light bands, while other contained dark bands. There were also bands of medium intensity. In some classes light and dark bands occured in the replications of the same cultivar. e) Correlations were found between certain combinations. f) The genetic distances between cultivars showed that there are genetic variation between durum wheat varieties, but that some bread wheat varieties are very closely related. g) A new nomenclature system was identified and this proved to be sufficient to distinguish 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. It is 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. It explains more of the variation between cultivars than the nomenclature system of Gupta and Shepherd (1990). d) Using this system, genetic markers must be identified for bread-making quality. It must also be tested if certain bands alone are responsible for bread-making quality 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 must also be tested.
Afrikaans: Die doel van die studie was om: a) Die HMW gluteniene in Suid Afrikaanse brood en durum koring te bepaal. b) Die effektiwiteit van LMW gluteniene te bepaal om tussen verskillende brood en durum kultivars te onderskei. c) Verskillende klasse LMW gluteniene te bepaal. d) The intensiteit verskille in bande tussen verskillende klasse te bepaal. e) Korrelasies tussen die verskillende klasse te bepaal. f) Die genetiese afstande tussen kultivars te bepaal. g) 'n Nuwe LMW glutenien nomenklatuur sisteem te ontwikkel om tussen kultivars te onderskei. Verskillende kultivars is ge-evalueer in 'n agtergrond wat vry is van gliadiene. 'n Vereenvoudigde een-dimensionele metode van Singh et al (1991) is gebruik. Die HMW en LMW gluteniene is op 'n enkele gel geëvalueer. 3. Die resultate was as volg: a) Baie kultivars het dieselfde HMW glutenien bande gehad. Dit het bewys dat HMW gluteniene nie gebruik kan word om tussen kultivars te onderskei nie. Dit is egter ideaal om saad suiwerheid voor kultivar vrystelling te bepaal. b) Die LMW gluteniene was baie effektief om tussen kultivars te onderskei. Dit was ook moontlik om tussen kultivars met naby genetiese agtergronde te onderskei. e) Daar was 39 verskillende klasse LMW gluteniene. Dit is bepaal m.b.v. die standaard afwykings van sekere kultivars. d) Sekere klasse het ook definitiewe intensiteit bande gehad. Bande in sommige klasse is uitgedruk as ligte bande terwyl ander donker bande was. e) Sommige LMW kombinasies was hoogs gekorreleerd. Negatiewe en positiewe korrelasies is gevind. f) Die genetiese afstande tussen kultivars is ook bepaal. Durum koring in Suid Afrika toon baie genetiese variasie tussen kultivars, maar daar is egter baie nabye genetiese verwantskappe tussen sekere brood korings. g) 'n Nuwe nomenklatuur sisteem is ontwikkel en dit was baie effektief om tussen kultivars te onderskei. 4. Die volgende afleidings kan gemaak word: a) Die HMW gluteniene is onvoldoende om te gebruik in Suid Afrika om tussen kultivars te onderskei. Dit kan egter met sukses gebruik word om saad suiwerheid te bepaal voor 'n kultivar vrygestel work. b) Die LMW gluteniene is baie effektief om tussen kultivars te onderskei. e) Die nuwe nomenklatuur sisteem is baie effektief om tussen kultivars te onderskei. Dit verklaar meer van die variasie tussen kultivars as die nomenklatuur van Gupta en Shepherd (1990). d) Die volgende stap is om genetiese merkers te identifiseer vir broodbak kwaliteit deur van hierdie sisteem gebruik te maak. Daar moet ook bepaal word of sekere bande alleen verantwoordelik is om brood kwaliteit te bepaal en of sekere kombinasies eerder 'n invloed het. e) Daar moet ook gekyk word of die intensiteit van sekere bande In invloed het op die broodbak kwaliteit van In kultivar.
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Plant proteins, Wheat genetics, Wheat -- Breeding, Thesis (Ph.D. (Plant Breeding))--University of the Free State, 1999
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