Population genetics of Puccinia triticina in North America

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Population genetics of Puccinia triticina in
North America
Maria E. Ordoñez James A. Kolmer
USDA-ARS-Cereal Disease Laboratory University of
Minnesota St. Paul, MN
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P. triticina collections

• 89 isolates from U.S. 2004-2005
• 37 isolates from the U.S. 1980s 1990s
• 20 isolates from Canada mid 1990s
• 5 isolates from durum wheat from Mexico 2003
• Total 151

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• Virulence phenotypes on 20 Thatcher near-isogenic
  lines
• Molecular genotypes with 23 simple sequence
  repeat markers (SSR)

89 virulence phenotypes
73 SSR genotypes
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Diversity of virulence and SSR genotypes
B L FPND P-17 TM-17 TM-17 TKM T S Durum
No. isolates 4 2 21 7 22 61 61 3 4 2
No. races 1 2 16 7 11 44 44 3 3 2
No. SSR genotype 4 2 15 7 13 25 25 2 3 2
Diversity index I 0.55 0.56 0.75 0.75 0.54 0.50 0.50 0.40 0.25 0.31
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NJ tree of clone corrected virulence phenotypes
B
C
M
FPN DL
TM- 17
P-17
S
Groups based on Vir/Avir to Lr1, Lr2a, Lr2c, Lr3,
Lr3bg, Lr17 and Lr28
TK
T
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Durum
NJ tree of clone corrected SSR genetic distances
FPND
B
P-17
S
L
T
TKM
9 groups based on SSR and virulence to Lr1, Lr2a,
Lr2c, Lr3, Lr3bg, Lr17 and Lr28
TM-17
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Distribution of SSR allelic variation, diversity
index, heterozygosity

• FST RST
• Among pop. 21 41
• Within pop. 79 59
• I 0.7577
• Ho 0.6508
• He 0.4507

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• Unrooted NJ dendrogram based on pair-wise
  FST values for SSR genotypes

Significant difference (plt0.05) FPND -
P-17 TKM - TM-17 T - all S
- all Durum - all
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Summary

• Several groups of P. triticina found in NA based
  on virulence phenotype and SSR genotype
• Difference in virulence and SSR genotypes suggest
  introduction or migration of a new race
• TM-17 and other T, K, M
• T and other T races
• Similar virulence and SSR genotype suggest
  mutation and selection
• T low on Lr14a and Lr20, and T high on Lr14a and
  Lr20
• T, M, K races
• P, F races
• P-17 and other P races different groups
• Durum isolates genetically different from common
  wheat isolates

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