MAPPING PROTEIN-PROTEIN INTERACTION DOMAINS IN WHEAT RHT-D1
Date
2025-05-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
Fusarium head blight (FHB) is a common fungal disease on wheat in western Canada, leading to loss of grain yield and reduced quality. Susceptibility to this disease has been linked to the presence of ‘Green Revolution’ alleles, Reduced height-B1b (Rht-B1b) and Reduced height-D1b (Rht-D1b), which produced semi-dwarf wheat varieties that benefited the world by increasing wheat production worldwide and solving food shortages in the 1960s. While these semi-dwarfing alleles are still relevant, farmers are now forced to trade the benefit of having high-yielding wheat crops with the risk of FHB. The semi-dwarf phenotype is caused by an altered DELLA protein that inhibits the gibberellic acid signalling pathway, which regulates major aspects of plant growth. DELLA proteins are also involved in various signalling pathways including jasmonate signalling, which controls plant defenses against biotic and abiotic stresses. The goal of my research is to separate these two functions by mapping the protein-protein interaction domain of RHT-D1 with other proteins involved in plant growth, and disease resistance. Through a yeast two-hybrid assay, the interaction domain for GA-receptor, GA-INSENSITIVE DWARF1 (GID1), in the presence of GA is within the N-terminal DELLA regulatory domain. However, it is also reported that wheat RHT-D1 can interact with wheat GID1 independent of GA. Protein truncations containing the RHT-D1 C-terminus display GA-independent interaction with wheat GID1 which is inconsistent with A. thaliana DELLAs. The RHT-D1 and wheat GID1 protein complex structure is predicted using AlphaFold3 and potential crucial amino acid residues required for this interaction are identified. On the other hand, another DELLA interaction partner, wheat jasmonate ZIM-domain1 (JAZ1), a protein involved in JA signalling, and wheat cryptochrome (CRY1) were found to interact with the C-terminal GRAS functional domain of RHT-D1. My findings indicate potential mutation targets for breeding wheat varieties that retain high yield potential, yet are resistant to diseases like FHB. Furthermore, my novel finding of GA-independent interaction between RHT-D1 and wheat GID1 may unveil a protein function of wheat RHT-1s distinct from A. thaliana DELLAs.
Description
Keywords
Fusarium head blight, Reduced height-1, gibberellin, semi-dwarf wheat
Citation
Degree
Master of Science (M.Sc.)
Department
Biochemistry, Microbiology and Immunology
Program
Biochemistry