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Friday, May 18, 2012
Kiwi Pathogen Tracked
The obvious preventive measure is to tightly control kiwi traffic
itself out of China. In the meantime the pathogen itself should be
amenable to established control measures and if we are lucky,
complete eradication outside its native locale. This needs
coordination between regulators and farmers generally, but that has
been done before.
In the modern era we are seeing the advent of a number of new
cultivators having the advantage of leaving the diseases of their
homelands far behind. That is a welcome advantage.
Let us hope control measures will keep it away while we solve this
devastating kiwifruit bacterium
by Staff Writers
(SPX) May 14, 2012
Boris Vinatzer of the Department of Plant Pathology, Physiology, and
Weed Science in Virginia Tech's College of Agriculture and Life
Sciences was one of the lead researchers who recently tracked a
deadly "kiwifruit canker" back to its likely source in
China. Credit: Virginia Tech.
international research team led by Virginia Tech Associate Professor
Boris Vinatzer and Giorgio Balestra of the University of Tuscia in
Italy has used the latest DNA sequencing technology to trace a
devastating pathogen back to its likely origin.
Pseudomonas syringae pv. actinidiae (Psa) has been threatening the
world's kiwifruit industry and destroying orchards in Europe, South
America, and New Zealand. In the four years since it was first
reported in Italy, the "kiwifruit canker" disease caused by
Psa has resulted in hundreds of millions of dollars in economic
A similar disease
broke out in the 1980s in China and Japan, but nobody knew if it was
the same pathogen that is currently wreaking havoc throughout the
rest of the kiwifruit world - until now.
Vinatzer and Giorgio
published a paper on May 9 in the journal PLoS ONE, which is the
first study released in a scientific journal to trace the bacterium
back to its likely origin of China.
is an associate professor in the Department of Plant Pathology,
Physiology, and Weed Science in Virginia Tech's College of
Agriculture and Life Sciences and Balestra is a senior researcher in
the Department for Agriculture, Forestry, Nature and Energy at the
University of Tuscia.
"It was detective
work," said Vinatzer. "By sequencing the DNA, we were able
to link all the bacteria back to a strain in China and determine
where it probably all began."
When New Zealand
reported the disease in 2010, the United States immediately banned
all imports of kiwifruit plant material and pollen to keep it from
infecting American crops, and so far, the bacteria have not been
found in the America. However, if the disease were to break out in
the U.S., Vinatzer's research will help slow down its spread - or
even eradicate the pathogen - through early and accurate diagnosis.
Vinatzer and his team
sequenced the entire DNA of Psa bacteria from kiwifruit trees in
China, Italy, and Portugal. They also analyzed some bacteria from New
Zealand, where kiwifruits are an almost $1 billion industry. Psa
causes a red or white bacterial slime to ooze out of the plant's
stems and branches. In the worst case, the entire plant wilts and
To find the root of
the disease, the researchers examined how the bacteria may have
evolved from the same ancestor by comparing the DNA from the
different bacteria to each other.
They found that the
bacteria from China, Europe, and New Zealand were almost identical;
but one small difference in one region of the DNA linked the New
Zealand outbreak to the Chinese bacteria. Vinatzer, Balestra, and
their colleagues think that the most likely scenario is that the
bacterium was imported from China into Italy and from China into New
"The first step
in stopping the spread of aggressive bacteria like Psa is knowing
where they come from and how they have spread," Balestra said.
"Now that we have sequenced the DNA and found its likely origin,
we can start to figure out ways to stop it and similar bacteria from
doing so much damage in the future."
Besides having direct
practical applications, the study will also lead to new insights into
the adaptation of bacterial plant pathogens to crops. That is an
integral part of Vinatzer's current research funded by the National
Science Foundation and for research carried out by Balestra's group
on detection of bacterial pathogens, funded by the Italian Ministry
of Agriculture and Forestry Policy.
Vinatzer and Balestra
were the lead authors of the paper. Angelo Mazzaglia of DAFNE,
University of Tuscia, and David Studholme of the University of Exeter
in the United Kingdom were co-first authors. Professor David Guttman
of the University of Toronto in Canada and Nalvo Almeida at the
Federal University of Mato Grosso do Sul in Brazil also contributed
their expertise to the team. Virginia Tech undergraduate student
Tokia Goodman and graduate student Rongman Cai performed an important
part of the experimental work and computer analysis in Vinatzer's
laboratory. The full report can be found here.