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Genetic and phenotypic insights in the adaptation of Magnaporthe oryzae to rice

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Genetic and phenotypic insights in the adaptation of Magnaporthe oryzae to rice

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Magnaporthe oryzae is a model and a major pathogen of rice

• Worldwide distribution • 5 M T losses/year (0.8%) • 2/3 fongicide market on rice • Localy 100 % losses

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But resistance breakdown common and rapid

Rice blast controlled by: fungicides

agronomic practices

resistant varieties

Rationale

Explained by:

- Gene for gene interactions

- Mutations in avirulence genes

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AvrPik AvrPita

Kanzaki et al Plant J. 2012 Chuma et al Plos Path. 2011

-9 cloned avr genes corresponding to rice R genes:

ACE1, AvrPi-a, AvrPi-b, AvrCo39, AvrPi-i, AvrPi-k, AvrPi-ta, AvrPi-zt, AvrPi9

-All kinds of mutations: Deletion, duplication, point mutation, transposon insertion…

-Frequency of mutation type depending on the avr gene -Frequency of virulent strains depending on the avr gene

- Each Avr/R gene couple probably has a unique co-evolutionary history - Mo samples not always appropriate and R gene deployment info lacking to study adaptation

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Two Mo genetic groups have migrated from two Mo diversity centers corresponding to rice domestication centers

Hypothesis: Mo genetic groups specialized on rice subspecies?

Saleh et al Molecular Ecology 2012; Saleh et al New Phytologist 2014

indica

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~ 6500 hectares

Acuce genotype for more than 110 years Yield ~ 5-7 t/ha

Traditional varieties No chemical fertilizer

High microbial diversity in the soil No fungicide

Area close to diversity center of M. oryzae

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> 30 varieties Mixtures

Glutinous (japonica)

and non-glutinous (indica)

Gao et al, 2012 mo de rn Acu ce Trad .

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HPN NG XG LJG AZG Acuce CH1184 S S R R R R CH1188 S S R R R S CH1186 S S R R R R CH1192 S S R R R R CH1209 S S S S R S CH1185 S S R R S R CH1205 S S R R R R CH1190 S S R R R R CH1207 S S R R R R CH1195 S S S S R R CH1189 S S S S S S CH1378 S R S S S S CH1193 S S S S S S CH1177 S S S S S S CH1197 S S S S S S CH1368 S S S S S S CH1387 S S S S S S CH1179 S R S S S S CH1178 R R S S S S CH1173 S S S S S S CH1383 S R S S S S CH1182 S S S S S S CH1198 S S S S S S CH1176 S S S S S S CH1322 S R S S S S CH1367 S R S S S S CH1290 S R S S S S Japonica Indica

Strains from japonica form a genetic group Strains from japonica are specialists

Other strains are generalists

Japonica rice is a potential universal host

In blue : strains clollected on japonica rice

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14 R-genes tested

10 R-genes different between japonica and indica

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Indica rice Japonica rice

Why so few indica isolates on japonica rice? Japonica isolatesare not virulent on indica rice

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R² = 0.6122 0 0,002 0,004 0,006 0 10 20 R² = 0.785 0 20 40 60 80 100 0 10 20 R² = 0.315 0 20 40 60 80 0 10 20 R² = 0.427 0 0,002 0,004 0,006 0,008 0 10 20 R² = 0.719 0 20 40 60 80 100 0 10 20 R² = 0.539 0 20 40 60 80 100 0 10 20 Huang Pi Nuo

(japonica - YuanYang) (japonica- YuanYang)Nuo Gu

Su rfa ce /le sion (c m 2 ) Pe rc en ta ge of S le sio ns S l es io ns /le af R² = 0.417 0 20 40 60 80 100 0 10 20 R² = 0.016 0 0,002 0,004 0,006 0,008 0 10 20 R² = 0.004 0 10 20 30 40 0 10 20 Number of AVR Nipponbare (japonica-Japan)

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Indica rice Japonica rice

Many R genes Many Avr genes

Specialization due to unbalanced situation between japonica and indica rice

Few Avr genes Few R genes

Japonica strains

Indica strains Incompatibility

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Some perspectives

Add supplementary fitness cost evaluation (sporulation)

Study specialization at local scale in other situations

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Acknowledgements

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Collaborators: YAU

JingJing Liao, Huichuan Huang

Xiaohong He, Chengyun Li, Youyong Zhu Romain Gallet

Elisabeth Fournier

Henri Adreit, Joëlle Milazzo, Christophe Tertois

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Thank you for

your attention

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