English:Wheat is one of the most important food crops and consumption in the past year was higher than production worldwide, which indicates improved wheat cultivars need to be developed to maintain the demand for wheat. One of the biggest threats of wheat is ever-evolving pathogens that overcome resistance. To overcome threatening diseases, breeders need to incorporate new resistant genes/QTL into improved cultivars. Incorporating different resistant genes/QTL into a single line using gene-pyramiding and MAS can enhance the breeding process. However, pyramiding of genes for resistance can lead to a decrease in baking quality characteristics, which are important for the milling and baking industry as well as for consumers. To overcome this problem, lines should also be tested for bread-making quality characteristics such as HMW-GS and the LUPP% which are directly linked to protein quality. The aim of the study was to identify rust and FHB resistant lines with good protein content. Rust and FHB resistant wheat lines were developed during previous studies. The best rust and FHB resistant lines were planted and self-pollinated. Lines were evaluated for the presence of five rust resistant genes/QTL (Lr19, Lr34/Yr18/Sr57, QYr.sgi.2B-1, Sr2 and Sr26) and four FHB resistant genes/QTL (Fhb1, Qfhs.ifa-5A-1, Qfhs.ifa-5A-2 and Fhb2) for two consecutive years. These selected rust and FHB resistant lines were also subjected to three biochemical tests namely SDS-PAGE, SEHPLC and RP-HPLC. PCR-based markers linked to HMW-GS alleles and the IBL.1RS translocation, associated with weak dough strength, were also tested. Since the breeding programme was still in an early stage, only few seeds per line were available and therefore biochemical tests that can be performed using single seeds were selected. Results from SDS-PAGE and molecular markers linked to HMW-GS were similar and therefore lines were further evaluated using only molecular markers. No correlations were detected for the RP-HPLC data of lines therefore it was excluded during further analysis. The rust and FHB resistant genes/QTL co-segregated based on their related parental lines. An additional round of self-pollination either led to higher levels of homozygosity for the selected traits or to the loss of traits due to recombination. MAS enabled the selection and enhancement of homozygous lines. Only a few offspring of one of the rust resistant lines contained the Sr26 gene, while the Lr34/Yr18/Sr57 gene was present in all tested lines. None of the rust resistant lines contained the Sr2 gene which is a major gene for resistance against stem rust and especially effective against the threatening Ug99 race. The top ten rust resistant lines all had the same rust resistant gene/QTL present (Lr19, Lr34/Yr18/Sr57 and QYr.sgi.2B-1) as well as the same protein quality alleles (Ax2*, Bx7+By8 and Dx5+Dy10). The LUPP% of these lines showed high levels of variation and was optimal (40% to 50%) for only one line. High levels of variation were detected for the FHB resistant markers in the FHB resistant populations. The top ten lines contained all six markers although the level of homozygosity varied. Four of these lines expressed both the Bx7+By8 and Bx17+By18 alleles and only one line did not express the Bx7OE allele. None of these lines expressed the 1BL.1RS translocation. Two of these lines showed a desirable LUPP%. Results indicated the preference towards rust or FHB resistance selection followed by selection for protein quality alleles and lastly the LUPP%. The top ten rust and FHB lines can serve as resistance sources in further breeding programmes.
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Molecular and biochemical characterisation of rust and Fusarium head blight resistant wheat lines
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