Revealing of Potato Disease Taking Hold
Posted by Unknown in Plant Diseases, Potato, Research and Technology, Vegetable on Saturday 26 January 2013
Infectious agents released from the late blight pathogen use a sticky patch of amino acids to adhere to potato plant cells
Late
blight is an economically devastating disease for potato farmers
worldwide, causing tens of billions of dollars worth of damage each
year. Phytophthora infestans, the causal agent of late blight, has
evolved to overcome fungicides and major resistance genes that have been
bred into commercial potato cultivars (Fig. 1). In order to dampen the
immune response of its host, P. infestans secretes molecules called
disease effectors at the site of infection.
Now,
a research team from Japan and the UK has determined the molecular
structure of the disease effector called avirulence protein 3a (AVR3a),
which is known to inhibit disease resistance in potato plants1.
Understanding the molecular structure and function of AVR3a will help
plant biologists to elucidate how P. infestans causes infection so that
they can develop better control measures.
Using
nuclear magnetic resonance spectroscopy, a technique employed to study
the configuration of molecules, the research team—led by Ken Shirasu
from the RIKEN Plant Science Center in Yokohama—identified a patch of
positively charged amino acids in the structure of AVR3a. The team found
the positively charged section of amino acids is conserved among
different versions of AVR3a from P. infestans and the model pathogen P.
sojae, indicating that this part of the overall structure could be
important to AVR3a’s role in the infection process.
By
examining potato plants to determine the final destination of AVR3a
within the infected host, the researchers found that the disease
effector binds to a lipid molecule called phosphatidylinositol phosphate
(PIP), which forms part of the structure of the potato cell membrane.
To
determine whether the newly identified section of amino acids is
essential to PIP-binding, Shirasu and his colleagues generated AVR3a
mutants by substituting the positively charged amino acids found in the
newly identified section with negatively charged amino acids. Using a
binding assay to investigate the interactions between molecules, the
researchers showed that the AVR3a mutants are unable to join to PIP and
hence attach to the potato cell membrane. They therefore proposed that
AVR3a may bind to PIPs in the cell membrane in order to remain
undetected by the immune system of the potato.
The
team’s next challenge is to determine how AVR3a molecules and other
disease effectors from P. infestans translocate into the host from the
site of infection. “Developing ways to block the action of AVR3a and
other disease effectors will provide means to control this damaging crop
disease,” says Shirasu.
The corresponding author for this highlight is based at the Plant Immunity Research Group, RIKEN Plant Science Center
This entry was posted on Saturday 26 January 2013 at 06:46 and is filed under Plant Diseases, Potato, Research and Technology, Vegetable. You can follow any responses to this entry through the RSS 2.0. You can leave a response.
- No comments yet.