Ji, Hao
(2014)
Using Genome-wide Approaches to Understand Natural Variation in Plant Fitness- and
Defense- Related Traits.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Plants have developed sophisticated defense networks to defend against their enemies and increase their fitness. However, there is often significant natural variation in plant fitness- and defense- related traits. If high levels of defense and reproduction are important, then why do plants not all have the highest possible values for these traits? One possible explanation is that these traits are costly to produce and allocation to one trait limits the resources available for another. Such tradeoffs are likely to be very important in understanding why phenotypic variation is maintained in natural populations. However, the genetic mechanisms that underlie them remain poorly understood. Coding regions of known defense- and seed- related genes are typically highly conservative in their sequences, suggesting that sequence differences in those genes are not responsible for the observed phenotypic variation. How then do plants achieve large phenotypic differences in these traits?
In my dissertation studies, I have dissected the genetic architecture underlying tradeoffs in defense and reproductive traits in the model plant, Arabidopsis thaliana and identified tradeoffs in a worldwide collection of wild Arabidopsis populations between a defense trait, leaf trichome number, and a reproductive trait, mass per seed. I found that two traits were negatively correlated at a major trichome-related locus, ETC2, which encodes a transcription factor. I also performed a Genome-wide Association (GWA) study searching novel candidate genes accounting for the observed variation in resistance to a bacterial pathogen, Pseudomonas syringae DC3000 and found that one of the candidate genes, AtABCG16, appears to assist plant resistance through its effect on abscisic acid-signaling in leaves.
Collectively, my work has taken advantage of reverse genetic mapping, traditional genetic techniques ,and bioinformatical analysis to improve our knowledge of plant natural variation. Moreover, my work suggests that the genetic basis of tradeoffs may involve both transcription factors and hormonal signaling. These findings are novel and are likely to explain why phenotypic variation persists in important defense traits. These results will therefore be important for predicting how these traits will respond to environmental change and how they can be manipulated in agricultural crops.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
31 January 2014 |
| Date Type: |
Publication |
| Defense Date: |
27 August 2013 |
| Approval Date: |
31 January 2014 |
| Submission Date: |
22 November 2013 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Number of Pages: |
168 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Biological Sciences |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Genetic mapping; Plant; Fitness; Defense |
| Date Deposited: |
31 Jan 2014 20:29 |
| Last Modified: |
08 Mar 2019 22:23 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/20083 |
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