Improving wheat grain yield by employing an integrated biotechnology approach

[摘要] ENGLISH ABSTRACT: Wheat is a widely cultivated crop as it forms a significant part of the world's diet, especiallywithin developing countries. However, food insecurity is increasing at a rapid rate and to meetthis demand, wheat yields need to increase by 50%, by the year 2050. To gain higher wheatyields, breeding efficiency needs to increase which can be done through employingbiotechnological approaches that can aid in achieving increased yields. Yield, however, isquantitatively inherited and strongly influenced by the genotype x environment interaction.Therefore, yield-determining traits that have less genotype x environment interaction shouldbe investigated to identify underlying inheritance of high yield, along with good husbandrypractises that can result in increased wheat yield.The aim of this study was to assess high-yielding genotypes through validating yielddeterminingtraits using genotypic and phenotypic screening as well as the use of these highyieldinggenotypes as male crossing parents within the male-sterility marker-assisted mediatedrecurrent selection breeding (MS-MARS) scheme for the improvement of grain yield. Theyield-determining traits as well as molecular markers associated to some of the yielddeterminingtraits were identified through literature. The molecular markers were validatedthrough genotypic screening and each yield-determining trait was phenotypically screened foreach genotype and statistically analysed. The validation of two mobile applications,SeedCounter and 1KK, that measures grain morphology was also executed.All molecular markers were validated as reliable diagnostic markers to be used in markerassistedselection (MAS) for identifying its specific yield-determining trait, except for onemarker. The statistical analysis for the yield-determining traits displayed that three genotypeswere better performing among this set of genotypes and therefore can be used as the malecrossing parents within the next MS-MARS cycle. The association of the molecular markerwith the yield-determining traits displayed negative correlations that suggests that the functionof the high-yielding genes are different within this set of genotypes. Only the SeedCounterapplication was validated to be used as a future phenotyping tool for grain morphology and theMS-MARS cycles were successfully executed.Future studies should include the validation of more mobile applications, the identification ofthe relationship between yield and these molecular markers identified and QTL mapping tocontribute to the understanding of the underlying genetic control of the desired phenotypes thatcontribute to higher grain yield.

[发布机构] Stellenbosch University