Genetic Adaptation of Prehistoric Barley to Osmotic Stress

  • Chioma Okpara

Student thesis: Phd


Barley (Hordeum vulgare L.) is one of the early crops that was domesticated in the Near East and accompanied farmers during migration. Barley, which grows naturally in south-west Asia, was carried to south-east Europe and eventually spread to other parts of the continent. Considering that the northern part of Europe is colder and wetter than the Asian origin, barley must have faced unfavourable environmental conditions thereby influencing its growth and development. Some transcription regulatory genes (TRG) found in plants, including barley, have been linked to adaptation to different environmental conditions, where they modulate transcription of stress-related genes. NAC1 and DREB1 are examples of stress-related TRG involved in osmotic stress response. This thesis tested the hypothesis that domesticated barley evolved adaptive changes beneficial to cold and wet environments in some TRG. The possibility of epigenetic changes that may hinder these gene expressions were also considered for the resequenced genes, while 30 TRG were reconstructed with available sequenced data as a result of the issue encountered during NAC1 resequencing. Hence, wild and traditional landraces of georeferenced barley seeds were sampled. Genomic DNA was extracted followed by long-range PCR amplification. Information from the Morex genome assembly was used as a reference to design primers for the PCR. Library preparation, NGS (MiSeq platform) and subsequently bioinformatics analysis was carried out. NGS results showed nonsynonymous substitutions in the DREB1 coding region for both populations. However, the observed variations within the landraces show that these did not evolve adaptive alleles that were absent in their wild progenitors. This study also identified a group of single nucleotide polymorphism (SNPs) within the landraces which might have helped to better adapt these to the osmotic pressures of the European plain especially in the NAC family from the reconstruction project. Yet, there were no signs of cytosine methylation on the queried accessions.
Date of Award1 Aug 2022
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorTerence Brown (Supervisor) & Catherine Walton (Supervisor)

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