Thesis (MSc (Genetics))--University of Stellenbosch, 2010. / Includes bibliography. / ENGLISH ABSTRACT: Wheat rust is a significant contributor to the total impact of diseases on sustainable wheat production. Genetic resistance, produced by using resistance genes from wheat and other related wild species, is the simplest and most cost-effective way to guard against these diseases. The pyramiding of resistance genes in a single line is a vital practice in bringing about durable resistance.
This study aimed to develop a series of doubled haploid (DH) wheat lines containing combination's of wild species genes for rust resistance. Rust resistance genes Lr19 (7BL), Sr31/Lr26/Yr9/Pm8 (1BS) and Lr54/Yr37 (2DL) were combined by means of crossing. Breeders. lines which have complex resistance including Lr24/Sr24 (3DL), Lr34/Yr18 (7D), Sr36 (2BS) and Sr2 (3BS), were used. Marker assisted selection (MAS) was used to type populations for the above mentioned genes. Using the DH method (maize pollination technique), an inbred population was developed from the selected lines, after which the lines were characterised molecularly for the resistance gene translocations which they contain.
The study produced 27 lines with diverse genetic profiles. Seven lines contain four translocations (Lr24/Sr24, Lr34/Yr18, Sr2 and Lr19 or Sr31) each, 11 lines contain three genes each, six lines contain two genes each and only three lines contain a single translocation (Lr24/Sr24). The reality that rust pathogens have already overcome three of the resistance genes in the final population . Lr19, Sr31 and Sr24 . is a clear indication of the value of using non-major gene resistance for bringing about durable resistance. The focus should fall ever more greatly upon the application of quantitative trait loci (QTL) for this purpose, which will result in MAS contributing to the development of more durable resistance.
The value of the integration of MAS and DH in combination with conventional breeding practices in breeding programmes has already been illustrated internationally for increasing the rate of cultivar development and this is reaffirmed by this study. / AFRIKAANSE OPSOMMING: Koringroes lewer jaarliks .n beduidende bydrae tot die totale impak van siektes wat volhoubare koringverbouing belemmer. Die mees eenvoudige en koste-effektiewe verweer teen hierdie siektes is genetiese weerstand, wat deur weerstandsgene vanaf koring, sowel as wilde verwante spesies, bewerkstellig word. Die stapeling van weerstandsgene in .n enkele lyn word as .n onontbeerlike praktyk om duursame weerstand tot stand te bring, geag.
Hierdie studie het ten doel gehad om .n reeks verdubbelde haploiede (VH) koringlyne te ontwikkel wat kombinasies van wilde spesie gene vir roesweerstand bevat. Roesweerstandsgene Lr19 (7BL), Sr31/Lr26/Yr9/Pm8 (1BS) en Lr54/Yr37 (2DL) is deur middel van kruisings gekombineer. Telerslyne wat oor komplekse weerstand beskik wat Lr24/Sr24 (3DL), Lr34/Yr18 (7D), Sr36 (2BS) en Sr2 (3BS) insluit, is gebruik. Merker-bemiddelde seleksie (MBS) is gebruik om populasies vir bogenoemde gene te tipeer. .n Ingeteelde populasie is vanaf die geselekteerde lyne met behulp van die VH metode (mielie-bestuiwing tegniek) ontwikkel, waarna die lyne molekuler vir die weerstandsgeentranslokasies waaroor hul beskik, gekarakteriseer is.
Die studie het 27 lyne met diverse genetiese profiele opgelewer. Sewe lyne bevat vier weerstandsgeentranslokasies (Lr24/Sr24, Lr34/Yr18, Sr2 en Lr19 of Sr31) elk, 11 lyne beskik oor kombinasies van drie gene elk, ses bevat twee gene elk en slegs drie lyne beskik oor .n enkele translokasie (Lr24/Sr24). Die realiteit dat die roespatogene reeds drie van die weerstandsgene in die finale populasie . Lr19, Sr31 en Sr24 . oorkom het, benadruk die waarde van die gebruik van nie-hoofgeenweerstand vir die daarstelling van duursame weerstand. Die fokus behoort toenemend meer op die aanwending van kwantitatiewe kenmerk-loci (QTL) vir hierdie doel te val en sal sodoende teweegbring dat MBS bydra tot die ontwikkeling van meer duursame weerstand.
Die waarde van die integrasie van MBS en VH in kombinasie met konvensionele telingsmetodiek is reeds internasionaal vir die versnelling van kultivarontwikkeling aangetoon en word ook deur hierdie studie herbevestig.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/5459 |
| Date | 12 1900 |
| Creators | Wessels, Elsabet |
| Contributors | Botes, W. C., University of Stellenbosch. Faculty of Agrisciences. Dept. of Genetics. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | Afrikaans |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 120 p. : ill. |
| Rights | University of Stellenbosch |
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