Dissertation
PROMOTER CHARACTERIZATION AND PROTEIN IDENTIFICATION OF THE PH1 GENE THAT REGULATES CHROMOSOME PAIRING IN WHEAT (TRITICUM AESTIVUM)
Doctor of Philosophy (PhD), Washington State University
01/2019
Handle:
https://hdl.handle.net/2376/100051
Abstract
Common wheat or bread wheat (Triticum aestivum L.) which belongs to the Poaceae grass family of Triticeae tribe is one of the major cereal crops around the world. It. The allohexaploid genome (AABBDD) of wheat has been evolved by two events of genome hybridization followed by duplication involving three ancestrally related grass species each contributing 14 chromosomes (2n). The allotetraploid wheat (Triticum turgidum, AABB) was the result of hybridization between
Triticum monococcum (AA) and a close relative of Aegilops speltoides (BB). The second round of hybridization added Aegilops tauschii (DD) to this polyploid and gave rise to modern day wheat. Its large genome (approximately 17Gbp) is arranged on 42 chromosomes (2n). Due to originating from a common ancestor, these three genomes share a great amount of similarity for DNA sequence in form of synteny and large sequence repeats. For this reason, each chromosome has four homoeologous partners which can potentially pair at meiosis. But wheat behaves like a diploid and strict bivalent are observed involving homologs during chromosome pairing. This regulated pairing was assigned to a locus at long arm of chromosome 5B termed as Ph1. Further studies mapped this regulator to a 2.5mb region and silencing of genes in this region identified the gene controlling pairing to true partners. The goal of this study was to identify the mechanism regulating transcription of this gene which provides unique expression profile. The bioinformatics analysis identified meiosis specific elements and novel conserved motif in Ph5B promoter. The evolutionary analysis of promoters revealed that after pollicization the Ph5B promoter has gained unique elements that provided meiosis specific and exceptionally high expression compared to its homoeologous counter parts. The transformation of Ph5B promoter deletion series constructs fused with GUSPlus reporter gene in wheat confirmed the functional validity of the elements identified by bioinformatics studies. The western blotting and immunolocalization of PH proteins confirmed synthesis of Ph5B protein. This protein was associated with centromere during early Prophase-I. The co-localization of PH protein with CENH3 at nuclear envelop during zygotene and delayed centromere movements observed in ph1b suggested the PH protein regulates centromere movements during homology search and recombination in meiosis.
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Details
- Title
- PROMOTER CHARACTERIZATION AND PROTEIN IDENTIFICATION OF THE PH1 GENE THAT REGULATES CHROMOSOME PAIRING IN WHEAT (TRITICUM AESTIVUM)
- Creators
- Muhammad Ahsan Khan
- Contributors
- Kulvinder S Gill (Advisor)Zhiwu Zhang (Committee Member)Mohan Kumar (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Crop and Soil Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 190
- Identifiers
- 99900581417701842
- Language
- English
- Resource Type
- Dissertation