Magnaporthe grisea is a notorious pathogenic fungus that causes rice blast disease
worldwide. Proteins secreted by the fungus are likely candidates for being effectors that
are potentially recognized by determinants of resistance or susceptibility in host plants.
However, knowledge of the role of secreted proteins of M. grisea is still limited. In this
study, I identified 29 proteins that were secreted into culture filtrates from M. grisea
strains expressing candidate proteins. I confirmed secretion of these proteins and tested
them for elicitor activity on plants. Among them, I studied two groups: cell wall
degrading enzymes (CWDEs) and small cysteine-rich proteins. Cysteine-rich proteins
have been shown in other systems to function as elicitors. Initially, I expressed and
purified proteins in M. grisea to obtain proteins by a homologous expression system.
Although this was effective for a number of proteins, the need for greater amounts of
protein led me to express several proteins in the Pichia pastoris system. Several candidate
proteins were purified and found to induce symptoms on rice and maize. Hypothetical
proteins MG10424.4 and MG09998.4 were both found to have elicitor activity. Lipase
MG07016.4 did not induce response of plants and we concluded that the lipase activity of
MG07016.4 does not function as an elicitor. I also purified a small cysteine-rich protein,
which belongs to the group of cluster 180 proteins in M. grisea, MG10732.4 from P. pastoris. It is able to cause yellowing symptoms and hydrogen peroxide production in
plants and it might contain elicitor activity.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/5827 |
| Date | 17 September 2007 |
| Creators | Shang, Yue |
| Contributors | Ebbole, Daniel J |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 11854216 bytes, electronic, application/pdf, born digital |
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