Thesis - Open Access
Master of Science (MS)
bud break, bud fruitfulness, grapevine, QTL
Grapevine (Vitis vinifera L. subsp. vinifera) is one of the most important and valuable fruit crops around the world and grape industries in the USA have been growing increasingly regarding the demand for highly productive and quality grapes that can be grown in the cold region around the USA. The development of new cultivars with these features is performed through grape breeding with the help of quantitative trait loci (QTL) mapping, marker-assisted selection (MAS), and and other technologies. In this study, we evaluated grapevine bud fruitfulness by position and bud break in controlled conditions. These traits are multi-genetic and understanding the genetics mechanism behind the complex traits will help to discover the underlying genes. The objectives of this thesis were to identify phenotypic variation in these traits and reveal QTL. A subset of 179 genotypes from a F2 mapping population developed from the self of a single F1 (16_9_2) derived from a cross between V. riparia and ‘Seyval’ were used. The F2s were grown in the greenhouse for bud fruitfulness and bud break study. Bud fruitfulness was determined, and an integrated genotype by sequencing (GBS) and rhAmpSeq linkage map (2519 markers) and standard interval mapping (SIM) were used to identify QTL. Two main QTL related to bud fruitfulness were identified, explaining 25.5 % of phenotypic variation on chromosome 4 and 5. Bud break phenology was studied to identify the rate of bud break QTL in the F2 genotypes. Bud break occurs after the chilling requirement is fulfilled and optimal growth conditions promote bud break. Six one-node cuttings of each genotype were forced under greenhouse conditions for thirty days and the growth stage of cuttings measured based on Modified Eichhorn-Lorenz (Modified E-L) phenology scale was monitored daily. Data were processed using the area under the curve concept (area under bud break progression curve, AUBPC) to capture the rate of bud break values for each genotype. SIM was conducted with the average AUBPC, bud break score at the third week, and bud break rate using R/qtl, 1000 permutations and the integrated GBS and rhAmpSeq linkage map. A major QTL was identified on chromosome 10 and explained 11.04% of the genotypic variation. Bud break and bud fruitfulness studies identified several QTL and these QTL can provide candidate genes that may be used further to dissect the mechanisms underlying bud break and fruitfulness for sustainable production of grapevine.
Number of Pages
South Dakota State University
Copyright © 2021 the Author
Bozkus, Seyma, "Exploring Quantitative Trait Loci Mapping for Bud Fruitfulness and Bud Break Traits in Grapevine F2 Population" (2021). Electronic Theses and Dissertations. 5208.