Date of Graduation

Spring 2009

Degree

Master of Natural and Applied Science in Agriculture

Department

College of Agriculture

Committee Chair

Laszlo Kovacs

Keywords

disease resistance, grape breeding, marker assisted selection, kinship analysis, positional cloning, powdery mildew, REN1, viticulture

Subject Categories

Agriculture

Abstract

The fungal pathogen Erysiphe necator is responsible for one of the most devastating diseases of Vitis vinifera grapevines, powdery mildew disease. A novel resistance to this pathogen has been observed in two Vitis vinifera cultivars from Central Asia, ‘Kishmish vatkana' and ‘Dzhandzhal kara'. A kinship analysis was performed on these two grapevines revealing a second degree relationship. The genetic locus associated with the resistance trait, REN1, was localized on Chromosome 13 by a bulked segregant analysis (Hoffman et al. 2008). In order to determine the precise location of REN1, a fine map was constructed across this region. Microsatellite markers were designed for a dense coverage of the REN1 region. Using existing and newly designed markers on 460 F1 plants in two populations, a positional cloning technique was employed to restrict the REN1 locus to a genetic distance of 1.4 cM between markers PSCtg147_14 and PSCtg147_20, which corresponds to a physical distance of 1.4 million bases on the PN40024 reference sequence. This has enabled an analysis of the gene content and features of the REN1 homologous region in PN40024, which is characterized by the presence of partial and complete NBS-LRR genes and has undergone rearrangements due to transposable elements. Markers flanking the restricted interval can be used for breeding with marker assisted selection of resistant plants, and newly designed markers within the restricted region can be used to test new recombinants for further restriction and analysis of the region containing the REN1 locus.

Copyright

© Courtney V. Coleman

Campus Only

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