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Quantitative traits of host-pathogen

interaction, and their contribution to

epidemic development in the wheat leaf

rust pathosystem.

H. Goyeau, G. Azzimonti, J. Papaïx, C. Lannou

Resistance components Aggressiveness components

Disease

HOST PATHOGEN

Quantitative traits of the host-pathogen

interaction

Assessment of quantitative traits

Growth Sporulation Infection

…In the glasshouse

A B

LP Latent Period SPL

SPS

LS

Sporulation per lesion

Per unit area

Lesion Size

40x

IE Infection Efficiency

Resistance components Aggressiveness components

HOST PATHOGEN

Disease

Quantitative traits of the host-pathogen

interaction

Questions :

• Relationships between different traits • Relationships between traits and field disease severity?

0

10

20

30

40

50

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

P3 P4 P5

Fréquence(%)

SID

CIE

CAMINS

BUS

FRA

LD7

AND

TRE

BAL

PBI

ECR

SOI

APA

0

0.2

0.4

0.6

0.8

1

RA

UD

PC

SID

CIE

CAMINS

BUS

FRA

LD7

AND

TRE

BAL

PBI

ECR

SOI

APA

0

0.2

0.4

0.6

0.8

1

RA

UD

PC

X

Experimental settings

13 Cultivars 3 PATHOTYPES

P3 P4 P5

2009 2010 2011

FIELD

3 years, 3 assessments per year

GLASSHOUSE

Quantitaive Traits (IE,

Latency, Sporulation)

Data Analysis

Distribution of variables

Bayesian Modelling -> Posterior Distribution

Regression to the estimated values

• Between quantitative traits • Between quantitative traits and field disease severity

• Quantitative traits (glasshouse) • Disease severity (field)

Correlations

PCA

Multiple colinearities

Simple linear Relationships between quantitative traits

LP

IE

SPS

IE

Positive rel. => increased R

LS

SPS

Negative rel. => Trade Off

SPL

SPS

NS (P=0,245)

Most of the components were correlated

Eigenvalues0

.00

.51

.01

.52

.02

.5 Multiple colinearities between quantitative traits

IE

SPS

SPL

LP

LS

PC1

PC2

Relationships between quantitative traits and field severity

IE

Date 1 Date 2 Date 3

All the quantitative traits were correlated with field disease severity, except for SPL.

P=1 P=1 P=1

Field

Disease

severity

Multiple Linear Regression

Disease severity at date i ~ PC1 * PC2

PC1 = axis 1 PCA (LP, LS, SPS and IE)

PC2 = axis 2 PCA (SPL)

Variable P value PC1 P value PC2

P value PC1*PC2

R2

Severity date 1

0.00029 ns ns 0.64

Severity date 2

0.00007 ns ns 0.72

Severity date 3

0.00005 ns ns 0.73

Infection Efficiency Latent Period Lesion Size Sporulation per unit area

Field disease severity correlated to

Multiple colinearities between quantitative traits and field severity

• Most of the quantitative traits were related (>0 or trade-off) [pleiotropic QTLs, trade-off]

• Field disease severity was correlated to quantitative traits assessed in controlled conditions [all the QTLs expressed in the glasshouse were expressed in the field]

• Assessment of quantitative traits in glasshouse experiments: – Different isolates => assessment of specificity

– Identification of diversified sources of resistance, to be combined

=> Durable Resistance

Conclusions

(Azzimonti et al., Plant Pathology, 2013)

Nicolas Lecutier

Anne-C. Zippert

Bénédicte Pariaud

Lucette Duveau

Thank you to …