Plant diseases on food crops can threaten global food security. Plants resist pathogen infection with an elaborate innate immune system to detect and respond to pathogen features and proteins. Specifically, plant intracellular innate immune receptors or nucleotide-binding domain leucine rich-repeat receptor (NLR) proteins are capable of recognizing pathogen effector proteins, which are deployed by pathogens to subvert host immunity. Wheat is a major food crop of global importance, and wheat yields are negatively affected by fungal pathogens, including stem rust caused by Puccinia graminis f. sp. tritici. Sr35 is a source of resistance to stem rust, and it confers near immunity to Ug99 and related races of stem rust. Sr35 encodes for a coiled-coil (CC)-type NLR protein that recognizes a stem rust fungal effector protein AvrSr35. Upon Sr35 activation by AvrSr35, cell death is observed, which is thought to help limit pathogen infection. Here, we dissect Sr35 protein to identify the domains involved in AvrSr35 recognition and cell death induction in both the model plant Nicotiana benthamiana and barley. We found that the CC-NB-ARC domains of Sr35 are important for cell death induction, whereas the LRR domain appears to function in AvrSr35 recognition. We also identified the subcellular localization of Sr35 protein in N. benthamiana, and we found it to be localized to the endoplasmic reticulum, where it is peripherally associated with the membrane and facing the cytoplasm. Finally, we investigated the nature of Sr35-AvrSr35 interaction. We did not find evidence for a direct interaction by yeast 2-hybrid (Y2H) assays. We also did not find evidence for Sr35 intramolecular interactions by Y2H. However, we did find that the auto-active Sr35 CC-NB-ARC D503V truncation variant was able to oligomerize by Y2H, tying oligomerization to activation of Sr35 protein. This work provides molecular insight into the function of a societally important plant immune protein.
|Commitee:||Coaker, Gitta, Melotto, Maeli|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 82/1(E), Dissertation Abstracts International|
|Subjects:||Plant Pathology, Plant sciences|
|Keywords:||AvrSr35, Effector, Nucleotide-binding leucine-rich receptor, Sr35, Stem rust, Wheat|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be