Thesis (M.Sc. (Agronomy)) --University of Limpopo, 2013 / In South Africa, wheat ranks first among the winter cereal crops produced and plays an important role in the country’s economy. The study was conducted to evaluate different South African wheat cultivars under irrigation for quality and yield parameters in Limpopo province. A field experiment was conducted during 2011 winter growing season under irrigation at the University of Limpopo experimental farm (Syferkuil). Eight wheat cultivars namely: Olifants, CNR 826, SST 347, Baviaans, Duzi, Steenbrass, SST 356 and Krokodil were laid out in a randomized complete block design with four replications for evaluation of yield and quality. The results showed that the highest grain yield obtained was 2372 kg/ha by CNR 826, and the lowest 311 kg/ha by SST 347. Flour yield, break flour yield, flour protein and mixogram development time and water absorption were not significantly different among cultivars. The highest hectolitre mass was 75.13 kghl-1for CNR 826 and the lowest 72.20 kghl-1 for Olifants. The highest falling number obtained was 187.00 sec for SST 347 and the lowest was 81.50 sec for Steenbrass. Cultivars CNR 826, SST 347, Steenbrass and SST 356 showed a good potential on protein content but Krokodil, Olifants and Baviaans had poor protein contents at 9.63%, 9.73% and 10.24% respectively. These results showed that wheat cultivars evaluated were within the requirements of the grading systems of South Africa as regards hectolitre mass and protein content. All these cultivars did not reach the required grade of 220 seconds in falling numbers with Olifants (97.50 sec), CNR 826 (103.50 sec), SST 347 (187.00 sec), Baviaans (146.75 sec), Krokodil (139.50 sec), Steenbrass (81.50 sec) and Duzi (50.25 sec), but only SST 356 met the requirement for utility grade with164.50 seconds. Olifants, CNR 826, Krokodil and Steenbrass yielded above 1500 kgha-1thus showing good potential under Limpopo conditions. These cultivars could be included in future performance evaluations in Limpopo.

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)], is recognized as one of the most destructive diseases of wheat (Triticum aestivum L. and T. durum L.) and barley (Hordeum vulgare L.) worldwide. Breeding for FHB resistance must be accompanied by selection for desirable agronomic traits. Donor parents with two FHB resistance quantitative trait loci (QTL) Fhb1 (chromosome 3BS) and QFhs.nau-2DL (chromosome 2DL) were crossed to four adapted SRW wheat lines to generate backcross and forward cross progeny. F2 individuals were genotyped and assigned to 4 different groups according to presence/ absence of one or both QTL. The effectiveness of these QTL in reducing FHB in F2 derived lines was assessed in a misted, inoculated scab nursery. Resistance alleles and the interaction among FHB resistance QTL have distinct behavior in different genetic backgrounds in wheat. Fhb1 showed an average disease reduction of 12%, however it did not result in significant improvement of FHB resistance in all populations. In general, for the four backgrounds studied, the QFhs.nau-2DL QTL as more effective reducing FHB (19% average reduction). The combination of Fhb1 and QFhs.nau-2DL is not necessary, but recommended and it improved resistance in all populations. Backcross derived (BC) progeny from four genetic backgrounds were planted in replicated plots (2011 and 2012) and in the scab nursery in 2012. Population 2 had its progeny characterized by 961 DArT markers distributed throughout the genome. Several high-quality polymorphic markers were identified and listed as good predictors of phenotypic traits like disease resistance, and improved agronomic and quality characteristics. Backcross and forward cross derived progenies were tested for FHB resistance and agronomic and baking quality performance for 4 different populations sharing the same donor parent for resistance QTL. The results confirmed that F2 populations were effective indicators of expression levels of QTL prior to extensive backcrossing. The QTL Fhb1 and QFhs.nau-2DL increased FHB resistance without detriments on agronomic and quality traits on wheat populations investigated. BC populations were assessed as breeding populations and established as being rewarding tools for derivation of inbred lines in a breeding program, being BC2 the most recommended from our results.

Thesis ( MScAgric) -- Stellenbosch University, 1997. / ENGLISH ABSTRACT: Stem rust is considered the most damaging of the wheat rusts causing yield losses of more than 50% in epidemic years. Similarly, Russian wheat aphids (RWA) can be regarded as one ofthe most devastating insect pests of wheat. Yield losses due to R W A primarily result from a reduction in plant resources (sucking plant sap). Secondary losses are incurred by viruses transmitted during feeding. Mapping disease and insect resistance genes that are effective against prevailing pathotypes and biotypes of South Africa will optimize their utilization in breeding programmes. The wheat line, 87M66-2-l, is homozygous for a single dominant stem rust resistance gene located on chromosome lD. This stem rust resistance gene has been derived from Triticum tauschii accession RL5289 and is here referred to as Srtau. The aim of this study was to determine the chromosome arm involved. Following the chromosome arm allocation of Srtau, its possible linkage with the genes Rg2, Lr 21 , Sr X and Sr 33 was studied. A telosomic analysis has shown that Srtau is located on chromosome arm 1 DS and is linked to the centromere with a recombination frequency of 21 ± 3 .40%. Glume blotch and a heavy mildew infection of segregating families planted in the field in 1996 made the linkage study between Lr 21 (leaf rust resistance) and Rg2 (glume colour) impossible. However, estimated linkages of 9 ± 1.9 map units between Sr33 (stem rust resistance) and Srtau, ± 6 map units between Sr X (stem rust resistance) and Sr 3 3 and ± 1 0 map units between Sr X and Srtau suggested that SrX, Sr33 and Srtau are closely linked on I DS. Taking existing map data into consideration, it seems that the most likely order of the genes is: centromere - Srtau - Sr 3 3 - Sr X. A single dominant R W A resistance gene, Dn5, was identified in the T aestivum accession 'SA 463' and is located on chromosome 7D. The aim ofthis study was to determine the chromosome arm involved. The possible linkage of Dn5 with the endopeptidase locus, Ep-D1 b. and chlorina mutant gene, cn-D1, was then studied. Endopeptidase zymograms of 'SA 463' revealed two unknown polymorphisms. F 2 monosomic analyses involving the chromosomes 7 A, 7B and 7D were performed in an attempt to identify the loci associated with these polymorphisms. Dn5 was mapped on chromosome arm 7DL. A recombination frequency of60 ± 4.53% between Dn5 and the centromere suggested the absence of linkage. Linkage between Ep-Dl and cn-Dl could not be calculated as a result of similar isoelectric points of the 7DL encoded endopeptidases of the parental material studied. Recombination frequencies of32 ± 4.97% between Dn5 and EpDl and 37 ± 6.30% between Dn5 and cn-Dl were, however, encountered. The two novel endopeptidase alleles encountered in 'SA 463' were designated as Ep-Dle and Ep-Ald. A RWA resistance gene was transferred from the rye accession ' Turkey 77' to wheat and in the process the RWA resistant wheat lines 91M37-7 and 91M37-51 were derived. No rye chromatin could be detected in these plants following C-banding. The aim of this study was to determine (i) on which chromosome the gene(s) is located, and (ii) whether the resistance can be the result of a small intercalary translocation of rye chromatin. A monosomic analysis of the RWA resistance gene in 91M37-51 has shown that a single dominant resistance gene occurs on chromosome 7D. The use of rye-specific dispersed probes did not reveal any polymorphisms between the negative controls and RW A resistant lines 91M3 7- 7 and 91M37-51 which would suggest that it is unlikely that the resistance was derived from rye. / AFRIKAANSE OPSOMMING: Stamroes word as die mees vemietigende graanroessiekte beskou en het in epidemiese jare oesverliese van meer as 50% tot gevolg. Russiese koringluise is eweneens een van die emstigste insekplae van koring. Russiese koringluise veroorsaak oesverliese deurdat dit plantsap uitsuig en die plant van voedingstowwe beroof. Dit tree egter ook as 'n virusvektor op en kan so indirekte oesverliese veroorsaak. Kartering van siekte- en insekweerstandsgene wat effektief is teen die Suid-Afrikaanse patotipes en biotipes, sal hulle gebruik in teelprogramme optimiseer. Die koringlyn, 87M66-2-l , is homosigoties vir 'n dominante stamroes-weerstandsgeen wat op chromosoom ID voorkom. Hierdie weerstandsgeen is uit die Triticum tauschii aanwins, RL5289, afkomstig en word hiema verwys as Srtau. Daar is gepoog om te bepaal op watter chromosoomarm Srtau voorkom, waama sy koppeling met betrekking tot die gene Rg2, Lr21 , SrX en Sr33 bepaal is. 'n Telosoomanalise het getoon dat Srtau op chromosoom-arm 1 DS voorkom en gekoppel is aan die sentromeer met 'n rekombinasie-frekwensie van 21 ± 3.40%. Segregerende populasies wat in 1996 in die land geplant is, is hewig deur aarvlek en poeieragtige meeldou besmet en dit het die moontlike bepaling van koppeling tussen Lr21 (blaarroesweerstand) en Rg2 (aarkaffie kleur) belemmer. Koppelingsafstande van 9 ± 1. 9 kaart-eenhede tussen Sr 33 (stamroesweerstand) en Srt au, ± 6 kaart -eenhede tussen Sr X ( stamroesweerstand) en Sr 3 3 en ± 1 0 kaart -eenhede tussen SrX en Srtau is geraam en toon dat SrX, Sr33 en Srtau nou gekoppel is. Die waarskynlikste volgorde van die gene op lDS is: sentromeer- Srtau- Sr33- SrX. 'n Enkele dominante Russiese koringluis-weerstandsgeen, Dn5, is in dieT aestivum aanwins 'SA 463 ' ge"identifiseer en kom op chromosoom 7D voor. Die studie het ten doel gehad om te bepaal op watter chromosoom-arm Dn5 voorkom, asook wat die koppeling van Dn5 met die endopeptidase lokus, Ep-Dl, en die chlorina mutante geen, cn-Dl , is. Endopeptidase simograrnme van 'SA 463' het twee onbekende polimorfismes getoon. Die gene wat kodeer vir hierdie twee polimorfismes is met behulp van F2 monosoom-analises wat die chromosome 7 A, 7B en 7D betrek, gei:dentifiseer. Dn5 is op chromosoom 7DL gekarteer. 'n Rekombinasie-frekwensie van 60 ± 4.53% is gevind vir die sentromeer en Dn5 en dui op die afwesigheid van koppeling. Koppeling tussen Ep-Dl en cn-Dl kon nie bepaal word nie omdat die endopeptidase bande geproduseer deur die ouerlike materiaal wat in die studie gebruik is, nie met sekerheid in die nageslag onderskei kon word nie. Rekombinasie-frekwensies van 32 ± 4.97% tussen Dn5 en Ep-Dl en 37 ± 6.30% tussen Dn5 en cn-Dl is egter bereken. Dit word voorgestel dat daar na die twee onbekende endopeptidase-allele wat in 'SA 463 ' voorkom, verwys word as Ep-Dle en Ep-Ald. 'n Russiese koringluis-weerstandsgeen is uit die rog-aanwins, 'Turkey 77', oorgedra na koring en in die proses is die Russies koringluis weerstandbiedende lyne, 91M37-7 en 91M37-51 , geproduseer. Geen rog-chromatien kon egter met behulp van C-bande in hierdie lyne waargeneem word nie. Die doel van die studie was om te bepaal (i) op watter chromosoom die geen(e) voorkom, en (ii), of die Russiese koringluis weerstandsgeen die gevolg kan wees van 'n klein interkalere translokasie van rog- chromatien. 'n Monosoom-analise van die Russiese koringluis-weerstandsgeen in 91M37-51 het getoon dat 'n enkele dominante weerstandsgeen op chromosoom 7D voorkom. Rog-spesifieke herhalende peilers het geen polimorfismes tussen negatiewe kontroles en die Russiese koringluis weerstandbiedende lyne 91M37-7 en 91M37-51 getoon nie. Dit is dus onwaarskynlik dat die weerstand in die lyne uit rog verhaal is.

A introdução de genes Rht, oriundos principalmente de programas de melhoramento da Ásia, Europa, Estados Unidos e México permitiu o avanço da cultura do trigo (Triticum aestivum L.) para áreas consideradas marginais. Nesse contexto, este trabalho se propõe avaliar a capacidade de combinação, heterose e heterobeltiose em um dialelo 8x8 afim de verificar o efeito pleiotrópico (único gene controla diversas características do fenótipo), ou seja, além da estatura, quais os componentes de rendimento que estão sendo alterados quando cultivares de maior estatura são cruzados com as linhas anãs CD 0827, CD 0985 e UTF 0605 disponibilizadas por programas de melhoramento genético nacionais de trigo. O experimento foi conduzido em Pato Branco – PR, na safra agrícola de 2012, em delineamento experimental de blocos casualizados com três repetições. As hibridações foram realizadas com oito genitores, sendo três anões (CD 0827, CD 0985 e UTF 0605) e BRS Pardela, Safira, BRS Tangará, CD 111 e CD 108, escolhidos por apresentarem estatura de planta média à elevada, potencial produtivo e demais caracteres agronômicos de interesse. Os valores dos quadrados médios da capacidade geral de combinação (CGC) foram superiores à capacidade específica de combinação (CEC) para todos os caracteres estudados, demonstrando maior contribuição dos efeitos gênicos aditivos. A capacidade geral de combinação das linhagens anãs (CD 0827, CD 0985 e UTF 0605) indicou as maiores contribuições para a redução da estatura de planta, em ambas as gerações avaliadas, com destaque para a linhagem UTF 0605. A CGC também indica que os genitores UTF 0605, Safira e BRS Tangará maximizam o número de afilhos férteis por planta (AFPL) e CD 0985 e CD 111 se mostraram efetivos em aumentar o número de grãos por planta (NGE). Os genitores Safira, BRS Tangará, CD 108 e entre as anãs CD 0827 se destacaram com os mais elevados valores quanto a CGC para rendimento de grãos por planta (RGP). Os genitores anãos UTF 0605, CD 0985 e CD 0827 são fontes promissoras de genes aditivos para o desenvolvimento de progênies de menor estatura de planta e maior número de afilhos férteis por planta, grãos por espiga e massa de mil grãos. Os cruzamentos CD 0827 x Safira, UTF 0605 x Safira, CD 0985 x CD 111, CD 0985 x CD 108, UTF 0605 x CD 111, UTF 0605 x BRS Tangará destacaram-se com maiores valores de capacidade específica de combinação para rendimento de grãos, e os dois primeiros foram superiores quando se considera os valores de heterose e heterobeltiose e depressão endogâmica. Os resultados deste estudo demonstram a viabilidade de utilização de linhagens anãs em programas de melhoramento genético. / The introduction of Rht genes, mainly from breeding programs in Asia, Europe, United States and Mexico has allowed the advancement of wheat (Triticum aestivum L.) to marginal areas considered. In this context, this study aims to evaluate the combining ability, heterosis and heterosis in a 8x8 diallel order to verify the pleiotropic effect (single gene controls several features of the phenotype), in other words, beyond the stature which components of income that are being changed when taller cultivars are crossed with dwarf lines CD 0827, CD 0985 and UTF 0605 provided by national wheat breeding programs. The experiment was conducted in Pato Branco - PR in the 2012 harvest, in a randomized block design with three replications. Hybridizations were performed with eight parents, three of them dwarfs (CD 0827 , CD 0985 and UTF 0605), BRS Pardela, Safira , BRS Tangara, CD 111 and CD 108. The values of the mean squares for GCA were higher than SCA for all traits indicating higher contribution of additive genetic effects. The general combining ability of the dwarf lines (CD 0827 , CD 0985 and UTF 0605) indicated the greatest contributions to the reduction of plant height in both generations evaluated, highlighting the UTF 0605 lineage. The CGC also indicates that UTF 0605, Safira and BRS Tangará parents maximize the number of fertile tillers per plant (NFPP) and CD 0985 , CD 111 were effective in increasing the number of grains per spike (NGS). The Safira, BRS Tangará, CD 108 and CD 0827 between dwarf parents stood out with the highest values for GCA for grain yield per plant (GYP) . The dwarf parents UTF 0605, CD 0985 and CD 0827 are promising sources of additive genes for the development of progenies of lower plant height and increased number of fertile tillers per plant, grains per spike and thousand grain weight. The CD 0827 x Safira, UTF 0605 x Safira, CD 0985 x CD 111, CD 0985 x CD 108, UTF 0605 x CD 111, UTF 0605 x BRS Tangará stood out with higher values of specific combining ability for grain yield, and the first two were higher when considering the values of heterosis and heterosis and inbreeding depression. The results of this study demonstrate the feasibility of using plant population used in breeding programs.

Os parâmetros mais utilizados na avaliação da qualidade industrial da farinha de trigo são obtidos por análises viscoelásticas de farinografia, alveografia, mixografia, e número de queda (NQ). Estes métodos tradicionais apresentam boa correlação com a qualidade industrial. Contudo, são caros, difíceis de serem implementados e demandam grande quantidade de sementes. Por este motivo, a seleção para qualidade de trigo geralmente é realizada em fases mais avançadas dos programas de melhoramento genético, nas quais a quantidade de sementes é suficiente para realização dos testes. Por isso, é altamente desejável a utilização de métodos preditivos da qualidade da farinha de trigo, de baixo custo, simples de serem implementados e que demandem pequena quantidade de amostra. Isso possibilitaria maior efetividade de seleção em fases iniciais dos programas de melhoramento, onde se concentra a maior variabilidade genética. Assim, o primeiro estudo desta dissertação objetivou determinar a eficácia do método alternativo da CRS (Capacidade de retenção de solventes) em diferentes genótipos brasileiros de trigo e verificar a associação entre CRS e os diversos parâmetros de qualidade industrial do trigo. Foram utilizadas sementes provindas de ensaio de Valor de Cultivo e Uso (VCU) de 22 genótipos de trigo (10 cultivares e 12 linhagens) cultivados no ano de 2014 em duas épocas de semeadura em 4 locais da região sul do Brasil (Abelardo Luz – SC, Cascavel – PR; Guarapuava – PR e Não Me Toque – RS). Foram realizados testes convencionais de qualidade de trigo: alveografia, número de queda, análise de cor e analisados os materiais através da CRS. Os resultados demonstraram que a CRS e os parâmetros de qualidade de trigo possuem significativa interação genótipo x ambiente (GxA). Observou-se associações significativas, de média magnitude, entre a CRS e as análises viscoelasticas, demonstrando que a CRS pode ser utilizada na seleção de genótipos para qualidade de trigo brasileiro. O segundo estudo objetivou determinar a sedimentação em SDS em diferentes genótipos brasileiros de trigo e observar a correlação entre SDS e o parâmetro de força de glúten, buscando aferir a eficiência desta metodologia. Este estudo foi conduzido utilizando sementes de trigo provenientes de experimentos executados em quatro locais (Abelardo Luz – SC, Cascavel – PR; Guarapuava – PR e Não Me Toque – RS) no ano de 2014 durante duas épocas de semeadura. Foram avaliados 25 genótipos, incluindo linhagens e cultivares comerciais, em ensaios de VCU. Foram realizados o teste convencional de alveografia para obtenção do parâmetro de força de glúten (W) e o método alternativo de SDS. O parâmetro SDS foi positivamente associado (r= 0,65**) com a força de glúten (W), podendo ser utilizado como preditor na seleção de genótipos de trigo para qualidade de panificação. / The parameters most used in evaluating the industrial quality of wheat flour are obtained by viscoelastic analyzes of farinograph, alveograph, and falling number (FN). These traditional methods have a good correlation with industrial quality. However, they are expensive, difficult to implement and require lots of seed. For this reason, selection for baking quality is usually carried out in more advanced stages of breeding programs, where the amount of seeds is sufficient to carry out the tests. Therefore, it is highly desirable to use batch quality predictive tests that are inexpensive, simple to implement and require a small amount of sample. This would allow greater selection effectiveness in the early stages of breeding programs, where the greatest genetic variability is concentrated. Thus, the first study of this dissertation aimed to determine the efficacy of the alternative method of CRS (Solvent retention capacity) in different Brazilian wheat genotypes and to verify the association between CRS and the various industrial quality parameters of wheat. Seeds from VCU of 22 wheat genotypes were cultivated in 2014 at two sowing dates in four sites in southern Brazil (Abelardo Luz - SC, Cascavel - PR, Guarapuava - PR and Não Me Toque - RS). Conventional wheat quality tests were performed: alveograph, falling number, color analysis and analyzed the materials through CRS. The results demonstrate that the CRS and wheat quality parameters have a significant G x E. There was a significant mean correlation between CRS and viscoelastic analysis demonstrating that CRS can be used as a predictor of wheat quality in Brazilian wheat genotypes. The second study aimed to determine the sedimentation in SDS in different Brazilian wheat genotypes and to observe the correlation between SDS and the gluten strength parameter, assessing the efficiency of the methodology. This study was conducted using wheat seeds from experiments conducted at four sites (Abelardo Luz - SC, Cascavel - PR, Guarapuava - PR and Não Me Toque - RS) in the year 2014 during two sowing seasons. Twenty-five genotypes, including commercial strains and cultivars, were evaluated in cultivation and use value (VCU) assays. The conventional alveograph test was performed to obtain the gluten strength parameter (W) and the alternative method of SDS. The SDS parameter shows an association (r = 0.65 **) with gluten strength (W) and can be used as a predictor in the selection of wheat genotypes for wheat protein quality.

The majority of wheat research in the world and in Canada is conducted by the public sector. The government of Canada has introduced legislation to update its plant breeder’s rights (PBR) legislation, making Canada compliant with the International Union for the Protection of New Varieties of Plants (UPOV) 91 convention, with the goal to stimulate private investment in wheat variety research. International experience with UPOV 91 reveals a wide range of outcomes depending on the specific royalty setting mechanisms allowed within their domestic legislation. This thesis compares Canada’s existing policy to three very different international examples (France, United Kingdom, and Australia) of UPOV 91 compliant royalty collection systems for wheat. The model presented is one of a monopolistic competitive wheat-breeding industry with the introduction of a new certified seed variety. Farmers have the option to use farm saved seed (FSS) or certified seed on their farm. The additional economic benefit created from the innovation and its distribution is analyzed and interpreted for both, farmers (social benefit) and breeders (private benefit). The results of the analysis show that while each UPOV 91 compliant model generates more revenue for farmers and breeders than Canada’s current policy, they tend to generate less than expected revenue in the short-run. If a country has strong intellectual property rights (IPRs), it will attract some domestic and foreign investment and possibly a beneficial collaboration between the public, private, and producer sector, also known as P4 (public-private-producer-partnerships).

[Truncated abstract] Lophopyrum elongatum, a wild relative of wheat, can be used as a source of novel genes for improving the salt tolerance of bread wheat. Na+ `exclusion? is a major physiological mechanism for salt tolerance in the wheat L. elongatum amphiploid, and a large proportion (~50%) of the improved Na+ `exclusion? is contributed by a gene(s) on chromosome 3E. This study integrated physiological analysis with comparative genomics to identify gene orthologues that may regulate Na+ transport, and designed and implemented molecular markers for developing wheat L. elongatum recombinant lines with reduced portions of L. elongatum chromatin retaining the Na+ `exclusion? trait. Physiological analysis of leaf Na+ accumulation in wheat L. elongatum substitution lines confirmed that the 3E chromosome contributes a major effect on reduced leaf Na+ accumulation in wheat when grown at 200 mM NaCl. Candidate genes from the model plant, Arabidopsis thaliana, controlling Na+ transport into and from cells (SOS1, HKT1) or compartmentalisation within vacuoles (NHX1, NHX5, AVP1, AVP2) were targeted for comparative analysis in wheat. Wheat gene orthologues were identified by BLAST searching to identify either FL-cDNAs or ESTs, which were subsequently used to amplify genomic DNA, and orthologues confirmed by similar intron-exon structure between Arabidopsis and rice. Intron-exon comparisons showed the majority of exons were conserved between Arabidopsis, rice and wheat, but also indicated exon shuffling events since divergence from a common ancestor. Gene orthologues were assigned to homoeologous chromosomes and non-syntenic regions between wheat and L. elongatum, with the SOS1 orthologue located on group 3 chromosomes in wheat and L. elongatum. ... The recombinant line 524-568 contains a small introgression on the distal end of the long arm of wheat chromosome 3A and represents the most desirable line presently available for further germplasm development. The main outcomes of this thesis have been an increased understanding of the physiology and evolution of orthologues for Na+ transport in wheat and L. elongatum, improved methodologies for designing alien-specific PCR markers, and the development of overlapping recombinant lines that provide a source of novel genes for pyramiding into wheat and improving its tolerance to salt stress.

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.

<p></p>Comprehensive information of breeding germplasm is a necessity to develop effective strategies for accelerated breeding. I characterized Purdue University soft red winter wheat breeding population that was subjectof intensive germplasm introduction and introgression from exotic germplasm. Using genotyping-by-sequences (GBS) approach, I developed ~15,000 single nucleotide polymorphisms (SNPs) and studied extent of linkage disequilibrium (LD)and hidden population structure in the population.The extent of LD and its decay varied among chromosomes with chromosomes 2B and 7D showing the most extended islands of high-LDandslow rates of decay. Four sub-populations, two with North American origin and two with Australian and Chinese origins, were identified. Genome-wide scans for signatures of selection using FSTand hapFLK identified 13 genomic regions under selection, of which six loci (<i>LT, Ppd-B1, Fr-A2, Vrn-A1, Vrn-B1, Vrn3</i>) were associated with environmental adaptation and two loci were associated with disease resistance genes (<i>Sr36 </i>and <i>Fhb1</i>).<br><p></p><div><br></div><div>The population was evaluated for agronomic performance in field conditions across two years in two locations. Genome-wide association studies identified major loci controlling yield and yield related traits. For days to heading and plant height, large effects loci were identified on chromosome 6A and 7B. For test weight, number of spikes per square meter, and number of kernels per square meter, large effect loci were identified on chromosomes 1A, 4B, and 5A, respectively. However, for grain yield<i> per se</i>, no major loci were detected. A combination of selection for other large effect loci for yield components and genomic prediction could be a promising approach for yield improvement.<br></div><div><br></div><div>In addition, the population was evaluated for FHB resistance under misted FHB nurseries inoculated with scabby corn across 2017-18 (Y1) and 2018-19 (Y2) seasons at Purdue Agronomy Farm, West Lafayette,in randomized incomplete block designs. Phenotypic data included disease incidence (INC), disease severity (SEV), <i>Fusarium</i> damaged kernels (FDK), FHB index (FHBdx), and deoxynivalenol concentration (DON). Twenty-five loci were identified at -<i>log</i>P ≥ 4.0 to be associated with five FHB-related traits. Of these 25, eighteen explained more than 1% of the phenotypic variations. A major QTL on chromosome 2Bi.e., Q2B.1 that explained 36% of variation in FDK was also associated with INC, FHBdx, and DON. The marker-trait associations that explained more than 5% phenotypic variation were identified on chromosomes 1A, 2B, 3B, 5A, 7A, 7B,and 7D. To investigate the applicability of other QTL with less signal intensity, the threshold criterion was lowered to -<i>log</i>P ≥ 3.0, which resulted in the identification of 67 unique regions for all traits. This study showed that the FHB-related traits have significant correlations with the number of favorable alleles at these loci, suggesting their utility in improving FHB resistance in this population by marker-assisted selection.The genotype and phenotype data produced in this study will be valuable to train genomic prediction models and study the optimal design of genomic selection training sets. This study laid foundation for the design and breeding decisions to increase the efficiency of pyramiding strategies and achieving transgressive segregation for economically important traits such as yield and FHB resistance.<br></div>

No description available.