Thesis (MSc.) -- Stellenbosch University, 1997. / ENGLISH ABSTRACT: An octoploid triticale was derived from the F1 of a Russian wheat aphid
resistant rye, 'Turkey 77', and 'Chinese Spring' wheat. The alloploid was
crossed (a) to common wheat, and (b) to the 'Imperial' rye to 'Chinese Spring'
disomic addition lines. F2 progeny from these crosses were tested for
Russian wheat aphid resistance and C-banded. Resistance was found to be
associated with chromosome arm 1RS of the 'Turkey 77' rye genome. This
initial work was done by MARAIS (1991) who made a RWA resistant,
monotelosomic 1RS ('Turkey 77') addition plant available for the study. The
F3 progeny of this monotelosomic addition plant was used to confirm the
RWA resistance on chromosome 1RS. The monotelosomic addition plant
was then crossed with the wheat cultivar 'Gamtoos', which has the 1BL.1 RS
'Veery' translocation. Unlike the 1RS segment in 'Gamtoos', the 'Turkey 77'-
derived 1RS telosome did not express the rust resistance genes 5r31 and
Lr26 which could then be used as markers. From the F1 a monotelosomic
1RS addition plant that was also heterozygous for the 1BL.1 RS translocation,
was selected and testcrossed with an aphid susceptible common wheat, 'Inia
66'. Meiotic pairing between the .rye arms resulted in the recovery of five
euploid, Russian wheat aphid resistant plants out of a progeny of 99
euploids. One recombinant also retained 5r31 and Lr26 and was allowed to
self pollinate. With the aid of SOS-PAGE profiles, Russian wheat aphid
resistant 1BL.1 RS translocation homozygotes were identified and it was
possible to confirm that the Russian wheat aphid resistance gene was in fact
transferred to the 1BL.1RS ('Veery') translocation.
Two attempts were made to map the Russiar, wheat aphid locus or loci.
(1) Telosomic mapping was attempted. For this purpose a plant with 2n =
40 + 1BL.1 RS + 1RS was obtained, and testcrossed with a Russian wheat
aphid susceptible wheat. (2) A disomic, recombined 1BL.1 RS translocation
line with Russian wheat aphid resistance but lacking the Lr26 and Sr31 alleles was crossed with 'Gamtoos' and the F1 testcrossed. The testcross in
both strategies were done with 'Chinese Spring'. In the first experiment the
Sr31 locus was located 10.42 map units from the Lr26 locus. The rust
resistance data implied that the genetic distance estimates may be unreliable
and therefore the laborious Russian wheat aphid resistance tests were not
done. In the second experiment a Russian wheat aphid resistance gene was
located 14.5 map units from the Lr26 locus. In the latter cross nonmendel
ian segregation of the Russian wheat aphid resistance evidently
occurred which implied that the estimated map distance may be inaccurate.
It was also not possible to determine the number of genes involved from the
data. / Digitized at 300 dpi Colour & b/W PDF format (OCR), using ,KODAK i 1220 PLUS scanner. Digitised, Ricardo Davids on request from ILL 25 April 2013 / AFRIKAANSE OPSOMMING: 'n Oktaplo"lede triticale is gemaak vanaf die F1 van 'n kruising tussen 'n
Russiese koringluis-weerstandbiedende rog, 'Turkey 77', en die
koringkultivar 'Chinese Spring'. Die alloplo"led is gekruis met gewone
broodkoring en met 'Imperial' rog/'Chinese Spring' disomiese addissielyne.
Die F2 nageslag vanaf hierdie kruisings is getoets vir Russiese koringluisweerstandbiedendheid
en C-bande is ook gedoen. Weerstand is gevind wat
geassosieer is met die 1RS chromosoomarm van 'Turkey 77'. Hierdie
oorspronklike werk is deur MARAIS (1991) gedoen en uit sy materiaal is 'n
monotelosomiese 1RS ('Turkey 77') addissieplant beskikbaar gestel vir die
huidige studie. Die F3 nageslag van hierdie monotelosomiese addissieplant
is gebruik om die weerstand teen die Russiese koringluis op chromosoom
1RS te bevestig. Die monotelosomiese addissieplant is ook gekruis met die
koringkultivar 'Gamtoos' wat die 1BL.1 RS-translokasie dra. Hoewel die 1RS
segment van 'Gamtoos' die roesweerstandsgene, Sr31 en Lr26 uitdruk, is dit
nie die geval met die 'Turkey 77' 1RS telosoom nie. Hierdie gene kon dus as
merkergene gebruik word. Vanuit die F1 is 'n monotelosomiese 1RS
addissieplant geselekteer wat ook heterosigoties was vir die 1BL.1 RStranslokasie.
Hierdie plant is getoetskruis met 'n luisvatbare gewone
broodkoring, 'Inia 66'. Meiotiese paring tussen die rogarms het daartoe gelei
dat vyf euplo"lede Russiese koringluis-weerstandbiedende nageslag uit 99
euplo"lede nageslag geselekteer kon word. Een rekombinant het ook Sr31
en Lr26 behou en is toegelaat om self te bestuif. Met behulp van SDSPAGE
profiele is Russiese koringluis-weerstandbiedende 1BL.1 RStranslokasie
homosigote ge"ldentifiseer en kon bevestig word dat die
weerstandsgeen vir die Russiese koringluis oorgedra is na die 1BL.1 RS
('Veery') -translokasie.
Twee strategies is gevolg om die Russiese koringluislokus of -loci te karteer:
(1) 'n Telosomiese analise is gedoen. 'n Plant met 2n = 40 + 1BL.1 RS +
1RS is verkry en met 'n luisvatbare koring bestuif. (2) 'n Gerekombineerde, disomiese plant met Russiese koringluis-weerstandbiedendheid maar sonder
die Lr26 en Sr31 allele is gekruis met 'Gamtoos' en die F1 getoetskruis. Die
toetskruisouer in beide die strategiee was 'Chinese Spring'. In die eerste
eksperiment is die Sr31-lokus 10.42 kaarteenhede vanaf die Lr26-lokus
gelokaliseer. Die raesdata het ge"impliseer dat onbetraubare genetiese
kaarteenhede geskat sou word en daarom is die omslagtige Russiese
koringluis weerstandsbepalings nie gedoen nie. In die tweede eksperiment
is die Russiese koringluis-weerstandsgeen op 14.5 kaarteenhede vanaf die
Lr26-lokus gelokaliseer. Nie-Mendeliese segregasie van die Russiese
koringluis-weerstand in hierdie karteringseksperiment het ge'impliseer dat die
berekende kaartafstand onakkuraat mag wees. Dit was ook nie moontlik om
op grand van die data die aantal gene betrakke af te lei nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/55770 |
| Date | 03 1900 |
| Creators | Horn, Marizanne |
| Contributors | Marais, G. F., Stellenbosch University. Faculty of Science. Dept. of Genetics & IPB . |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 78 p. : ill. |
| Rights | Stellenbosch University |
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