Invasion Genetics of Russian Wheat Aphid in Western China and Worldwide. Bo Zhang1, Le Kang2, Owain Edwards3 and Susan Fuller1 1
Queensland University of Technology, 2 Chinese Academy of Sciences, 3 CSIRO Entomology
biosecurity built on science Cooperative Research Centre for National Plant Biosecurity
Worldwide distribution of RWA on cereals 1947
1989
1986
1901
Native to central Eurasia
1980
1940s/50s
1980s/90s
1988
1978
Diuraphis noxia (Russian wheat aphid) biosecurity built on science
Biosecurity Australia The Grains Industry Biosecurity Plan (IBP) provides a framework for biosecurity risk mitigation measures in the industry.
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The Problem  The Australian grains industry is developing a RWA response plan based on pre-emptive breeding, but RWA is known to develop virulent biotypes that can overcome host plant resistance.  It is likely that more genetically-diverse populations of RWA exist in endemic areas such as China and may represent a more abundant source of virulent clones.  Very little is known about RWA in its endemic range.
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Study Aims To examine:
whether RWA is native or invasive in China;
the genetic relationships among invasive and endemic RWA from around the world;
the pathway of historical RWA invasions; &
whether there is a genetic basis for invasiveness and virulence.
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(i) Is Chinese RWA native or introduced? ďƒ˜RWA was first discovered in Xinjiang Uygur Autonomous Region, western China, in 19751. ďƒ˜Up to 1999, no other province has reported RWA invasion2.
1. Li et al., 1990 2. Zhang et al., 1999 biosecurity built on science
Genetic differentiation among Chinese RWA
Within northern sites Ave Fst = 0.07 Ave Fst = 0.11 Tacheng A&B
Haba Altay
Berqin
Fuhai Ermin
Ave Fst = 0.16 Ave Fst = 0.27
Yumin
Toli
Hobuksa Manas
Qapqai
Urumqi
Qitai Mori
Wuqia
Pishan Cele
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Population Expansion t = τ/2μ
14000 12000
Frequency
10000 8000 Observed
6000
Simulated
4000
If 0.7 %/myr < μ < 1.2%/myr, t = 8,000 to 5,000 generations
Model Freq.
2000 0 10 5
21
3
2 4
35
64
If μ = 1.77%/myr, t = 3,200 generations
Pairwise differences
Mismatch distribution for Chinese RWA suggests that populations have undergone a recent expansion during the last 10000 years.
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(ii) Worldwide RWA population genetics Population structure
Endosymbiont network
Population tree China Tajikistan
TK IR
1
2
3
SY
4
KY
5
SA
6
ME
34
US,CH,AR
Hungary France
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Global invasion pattern of RWA Mid-20th century, global invasion triggered by: •Range expansion through Middle East & Nth Africa •Distribution of contaminated material? •Development of asexual lineages?
1986
1947
1980
1988
1978
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(iii) Worldwide salivary Peroxidase allelic pattern A Hungary
US
Syria Mexico
China
Turkey
B
Tajikistan Iran
Kenya Chile
South Africa
Argentina
A B
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Summary RWA is indigenous in China for a long term, which can date back to wheat domestication and cultivation practices in Asia in the Holocene. The unique invasive pathway was found from South Africa to Americas, and independent invasion sources to Africa from Middle East. RWA salivary gland gene has undergone natural selection in native ranges.
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Publication
B. ZHANG, O. R. EDWARDS, L. KANG, S. J. FULLER. Russian wheat aphids (Diuraphis noxia) in China: native range expansion or recent introduction? Molecular Ecology. 21(9): 2130–2144.
B. ZHANG, O. R. EDWARDS, L. KANG, S. J. FULLER. Worldwide Russian wheat aphids (Diuraphis noxia) population genetics. In prep.
B. ZHANG, O. R. EDWARDS, L. KANG, S. J. FULLER. Worldwide Russian wheat aphids (Diuraphis noxia) salivary gland genes variation. In prep.
B. ZHANG, C. Ma, O. R. EDWARDS, L. KANG, S. J. FULLER. Mitochondrial genome of Russian wheat aphids (Diuraphis noxia). In prep.
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Acknowledgements CRC Plant Biosecurity, QUT, CSIRO & CAS for funding My advisors for supporting (money, papers, life & culture) Collaborators who have provided samples
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