Thesis
Towards understanding the genetics of pre- and post- harvest traits: bitter pit in apple and chilling requirement in pear
Washington State University
Master of Science (MS), Washington State University
2013
Handle:
https://hdl.handle.net/2376/103128
Abstract
Crops from the Rosaceae family are very important for Washington agriculture but many factors can decrease yield and quality of the main tree fruit species of this family. One of the biggest problems in apple is bitter pit, a nutritional disorder. The main cause is a calcium deficiency that results in localized cell death which develops into black, corky pits. It is hard to define the stages and the mechanisms behind its development because many different factors influence its occurrence. The genetic and phenotypic characteristics define the generation of the pits, but also agronomical practices can have an important effect. A previous study in the Dhingra lab identified two homologs of a putative bitter bit associated gene (MdPBAG) in apple. These genes have been cloned and sequenced to detect genetic variability among eight commercial cultivars and eight seedlings with differing susceptibility to bitter pit. This genetic analysis was the first step in a larger genomic screen to detect QTLs for bitter pit in apple. Several QTL regions were identified and one of the two MdPBAG homologs was found to be approximately located 1cM apart from a QTL on linkage group 3. The QTL regions were also analyzed to identify candidate genes and their expression was evaluated to determine if they might be involved in the genetic mechanism inducing the disorder. Consumers find pear fruit problematic; 'ripe and ready-to-eat' pears are difficult to source. Many cultivars of pear only start to mature after a cold storage period which switches on the autocatalytic production of ethylene. Previous reports indicate that the gene family ACS seems to have a major function in determining the length of the required cold treatment. In this project, three cultivars, with different chilling requirements were analyzed to identify specific alleles for the genes of the ACS family. New ACS alleles, compared to the previously reported ones, were identified in both Anjou and Comice. In order to advance this study further, a segregating population was created, making reciprocal crosses of the three selected cultivars to create new genetic recombinants with differing cold requirements and to analyze their segregation.
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Details
- Title
- Towards understanding the genetics of pre- and post- harvest traits
- Creators
- Marco Galli
- Contributors
- K. Evans (Degree Supervisor)Amit Dhingra (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Horticulture, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525059301842
- Language
- English
- Resource Type
- Thesis