Investigating LysM effector function and the biotrophic growth phase of Magnaporthe oryzae
Mentlak, Thomas Andrew
Date: 12 June 2012
Thesis or dissertation
Publisher
University of Exeter
Degree Title
PhD in Biological Sciences
Abstract
During intracellular biotrophic growth, the rice blast fungus Magnaporthe oryzae secretes a
large battery of effector proteins, which are thought to suppress host cell defence responses.
Although a number of these effector proteins have been identified, their precise biological
functions and contribution towards plant infection remains ...
During intracellular biotrophic growth, the rice blast fungus Magnaporthe oryzae secretes a
large battery of effector proteins, which are thought to suppress host cell defence responses.
Although a number of these effector proteins have been identified, their precise biological
functions and contribution towards plant infection remains unclear. In this thesis, I report that
during biotrophic growth, the secretion of a LysM effector protein, Slp1, is required for rice
blast disease. I show that Slp1 binds chitin and is able to suppress the chitin-induced oxidative
burst and defence gene-expression in rice cells. Slp1 competes with the membrane-localised
chitin receptor CEBiP in rice, and this competitive interaction results in a reduction in virulence
associated with Δslp1 null mutants. Slp1 is secreted by intracellular hyphae specifically during
biotrophic growth, and accumulates around hyphal tips at the plant-fungal interface. Using
transgenic rice lines which express fluorescent marker proteins targeted to the plasma
membrane and endoplasmic reticulum, I investigate the biotrophic growth phase of M. oryzae. I
show that the rice host plasma membrane becomes tightly apposed to invasive biotrophic
intracellular hyphae. I also show that the rice host plasma membrane and endoplasmic reticulum
accumulate around the Biotrophic Interfacial Complex (BIC), a bulbous structure attached to the
sub-apical region of intracellular fungal hyphae, which accumulates fluorescently-labelled
avirulence effector proteins. Using a fungal plasma membrane marker, I show that the BIC
resides outside the fungal plasma membrane and cell wall is made exclusively of plant cellular
material.
Doctoral Theses
Doctoral College
Item views 0
Full item downloads 0