TRANSCRIPT PROFILING AS A METHOD TO STUDY FRUIT MATURATION, TREE-RIPENING, AND THE ROLE OF "TREE FACTOR" IN 'GALA' AND 'FUJI' APPLES

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dc.contributor.advisorWalsh, Christopher Sen_US
dc.contributor.authorLin, Shu-feien_US
dc.contributor.departmentPlant Science and Landscape Architecture (PSLA)en_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2005-08-03T14:14:34Z
dc.date.available2005-08-03T14:14:34Z
dc.date.issued2005-04-20en_US
dc.description.abstract'Gala' and 'Fuji' are two high-quality apple (Malus domestica Borkh) cultivars. Their fruits mature and tree-ripen over a long period of time, and are resistant to pre-harvest drop. "Tree factor," a putative inhibitor of system 2 ethylene production is hypothesized to account for differences in ethylene production between attached and detached apple fruits. Three years of field data revealed two distinct patterns of maturation and ripening behavior in these two cultivars. 'Gala,' an early cultivar, demonstrated a typical positive "tree factor." Studies of the ripening pattern of 'Fuji' apple, which is a late-maturing cultivar, did not. 'Fuji' data were confounded by cold weather in the late fall. The natural progression of tree-ripening did not lead to the high concentrations of internal ethylene routinely measured in stored fruits. The stimulation of ethylene found in picked 'Gala' fruits ripened in the orchard might be explained by wounding stress coupled with a loss of nutrients and the water stress. Our alternative explanation for "tree factor" is the effect of continued termination of the phloem and xylem connection. The strength of the "tree factor" declined as 'Gala' fruit maturity progressed. Therefore, the "tree factor" tends to be more obvious in fruits with shorter growing period that mature during warm weather. To investigate differential gene expression that accompanies maturation and tree ripening, we used cDNA-AFLP (Amplified Fragment Length Polymorphism) to identify changes in transcript profiling during tree-ripening, and in the ripening of harvested fruits. Two hundred differentially-expressed transcript-derived fragments were isolated from 'Gala.' Ripening-related genes including those known to function in the key processes of defense and stress, cell wall degradation, pigment production and aroma biosynthesis were identified. Clones similar to housekeeping genes involved in protein biosynthesis and degradation, intracellular trafficking and sorting, cell structure and mobility, and metabolism-associated genes were also isolated. Expression patterns of these transcript-derived fragments were verified by using a different 'Gala' sample set on microarray and/or Northern blots. Our study supports the hypothesis that many ripening processes are under transcriptional control and that most of these differentially-expressed genes are highly conserved in fruits.en_US
dc.format.extent3833682 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/2454
dc.language.isoen_US
dc.subject.pqcontrolledBiology, Plant Physiologyen_US
dc.subject.pqcontrolledAgriculture, Plant Cultureen_US
dc.subject.pqcontrolledBiology, Molecularen_US
dc.subject.pquncontrolledRosaceaeen_US
dc.subject.pquncontrolledFruit Maturation and Ripeningen_US
dc.subject.pquncontrolledApple ESTsen_US
dc.subject.pquncontrolledEthylene biologyen_US
dc.subject.pquncontrolledcDNA-AFLPen_US
dc.subject.pquncontrolledGene Expressionen_US
dc.titleTRANSCRIPT PROFILING AS A METHOD TO STUDY FRUIT MATURATION, TREE-RIPENING, AND THE ROLE OF "TREE FACTOR" IN 'GALA' AND 'FUJI' APPLESen_US
dc.typeDissertationen_US

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