Evolutionary and functional study of plant cell wall polysaccharide glucomannan

My PhD thesis focused on the cell wall polysaccharide mannan; I investigated the function, evolution, and mutant phenotypes of its synthase. The main chapter consists of three independent parts. Chapter2 addresses the question, “In which group of evolutionary stages does β-GGM (β-galactoglucomannan) exist?”. The results suggest that β-GGM is likely to be specific to dicots and that the key event of acquisition of MBGT (mannan bgalactosyltransferase) activity may have occurred in this group. Chapter3 addressed the following question: “Was MBGT acquired convergently in Asterids and Rosids?” The results show that MBGT in Rosids is present in GT47A-VII (Glycosyltransferase family 47A subclade VII), whereas that in Asterids is present in GT47A-III, suggesting convergent evolution from different xyloglucan galactosyltransferases. Chapter4 addressed the question, “What is the role of CSLD (cellulose synthase-like D) glucan?" Although we could not clarify a role for CSLD glucans, we found that constitutive immune response occurs in the *csld5* mutant. Furthermore, we found that lignin deposition induced by a transcription factor MYB15 (myeloblastosis family 15) enhances pathogen resistance in *csld5*. These results not only demonstrate the diversity of mannan-modifying enzymes, but also highlight the importance of their physiological roles, which plants have acquired throughout their evolutionary history. Furthermore, they show that CSLD glucans, polysaccharides related to mannan, are not just minor structures but also have a role in the context of adaptation and immunity.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2024

Author dc:creator

• Ishida, Konan

Advisor dc:contributor.advisor

• Dupree, Paul

• Evolution
• Glycosyltransferase
• Plant cell wall
• Plant physiology

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/2096b5fe-baf4-4a81-863d-fee7652e484d/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.109202

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/369357