Studies on the genetic basis for thermotolerance in Arabidopsis thaliana

Nurcahyanti, Agustina (2009) Studies on the genetic basis for thermotolerance in Arabidopsis thaliana. MSc(R) thesis, University of Glasgow.

Abstract

Vast tracts of land are available for arable food production but much of this is
located in hot, arid regions. For crops to thrive in these conditions they will need
to show improved drought tolerance and also improved thermotolerance as low
water availability reduces transpiration resulting in increased leaf temperatures.
Identification of traits and genes involved in drought tolerance has been one of the
major areas of plant research over the last decade, but thermotolerance has
received little attention. In this study two approaches were used to identify the
genetic basis for improved thermotolerance in the model plant Arabisopsis thaliana.
In one set of experiments a gain-of-function heat stress screen (44 oC for 3 hours)
was performed on a collection of Activation Tagged lines where individual plants
were engineered to transcriptionally activate random sequences in the
Arabidopsis genome. Preliminary experiments confirmed prior exposure to 37 oC
for 1-3 hours acclimates Arabidopsis so that it survives better a subsequent heat
stress event. A total of ~14,600 lines were screened and three mutants were
isolated; secondary screens confirmed their improved thermotolerance phenotype,
but in subsequent generations one of the lines developed a hypersensitive
phenotype, another reverted to wild type, whilst the third retained its
thermotolererant phenotype. This loss-of-phenotype through generations was
attributed to gene silencing events which are not uncommon in dominant
mutants. Further experiments on these three lines are now required to identify the
loci of the disrupted gene(s) in each of these lines.
In the other set of experiments transgenic lines carrying a construct designed to
constitutively express a MYB transcription factor were characterized. This MYB
has been shown to confer salinity tolerance in Arabidopsis, and transcript
profiling using cDNA microarrays had identified several sequences may be under
the control of this MYB. Quantitative PCR (QRT-PCR) demonstrated that compared with wild type MYB expression in the transgenic lines was over 500
times greater, and that transcript for a small heat shock protein AtHSP17.6, is 17
times more abundant. These transgenic lines were shown to have an improved
thermotolerance. Treatment of wild type plants with 5 x 10-4 M ABA increased the
expression of this MYB seven-fold, suggesting this transcription factor forms part
of the ABA-dependent pathway for the activation of abiotic stress responses in
Arabidopsis.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Arabidopsis thaliana, thermotolerance, AtMYB64, heat shock protein
• Subjects: Q Science > QK Botany; S Agriculture > S Agriculture (General)
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
• Supervisor's Name: Dominy, Dr. Peter
• Date of Award: 2009
• Depositing User: Miss Agustina Nurcahyanti
• Unique ID: glathesis:2009-631
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 18 Mar 2009
• Last Modified: 10 Dec 2012 13:20
• URI: https://theses.gla.ac.uk/id/eprint/631