Title page for ETD etd-0710102-132751


Type of Document Master's Thesis
Author Kokkinos, Charalambos Demetriou
Author's Email Address ckokkin@lsu.edu
URN etd-0710102-132751
Title Viral Stress Activation of Retrotransposons in Sweetpotato [Ipomoea Batatas (L.) Lam.]
Degree Master of Science (M.S.)
Department Horticulture
Advisory Committee
Advisor Name Title
Don R. LaBonte Committee Chair
Christopher A. Clark Committee Member
Rodrigo A. Valverde Committee Member
Keywords
  • relative quantification
  • retrotransposons
  • viral stress activation
  • Ipomoea
  • real-time quantitative PCR
  • sweetpotato
  • taqman
Date of Defense 2002-07-02
Availability unrestricted
Abstract
Mutations in sweetpotato [Ipomoea batatas (L.) Lam.], which are poorly understood, are widely implicated as a component in cultivar decline. In sweetpotato, mutations are also likely to result from the activity of plant retrotransposons, which are known to be present in the sweetpotato genome. The majority of the transcriptional activity of plant retrotransposons that has been characterized to date, is stress-induced, involving both biotic and abiotic stresses. Viral infection, a form of biotic stress, is also one that commonly occurs in sweetpotato. The objective of this study is to test whether viral stress, in the form of single and combined viral infections, transcriptionally activates Ty1-copia elements, a family of LTR retrotransposons, at the whole-plant level. To assess activation, transcripts from the RT domain of Ty1-copia elements were relatively quantified using Real-Time Quantitative PCR. Relative amounts of transcripts from five viral inoculation treatments were then compared to those from the virus-free plants of the control treatment. Results showed that the relative amount of Ty1–copia transcripts from the viral combination treatment of BWFT-3 (SPCSV isolate) + SPFMV, which produced the most severe symptoms on both varieties tested, was significantly higher than the other viral treatments and the control. No significant difference was observed among the other treatments. No significant difference was also observed in transcript amounts between the two cultivars inoculated with the same virus. This represents the first study examining the effect of stress on relative transposon transcriptional activation.
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