R gene mediated response

(1)

R gene mediated

response

(a)

gene Avr

_R

S

gene Avr

_S

S

Host cell

Host cell Host cell Host cell Avirulent pathogen Virulent pathogen Virulent pathogen Avirulent pathogen R-gene R-gen

Gene for gene model (Flor, 1971)

- specific response

- usually used in plant breeding

- mechanism widely known

Maize

Hm1/Hm2

against

Cochliobolus carbonum

race 1

encode HCTR (toxin reductase) that inactivates

(2)

Pto

Ser/Thr PKase

N, L6

TIR/NBS/LRR

Rps2, Rpm1

LZ/NBS/LRR

Cf-2, Cf-9

eLRR

Xa21

eLRR, quinase

TIR

NBS

LRR

N

_C

Main types of R genes

CC

NBS

LRR

N

C

quinase

TM

LRR

N

_C

TM

LRR

N

_C

N

C

Signal

transduction

Protein-protein

interaction

signaling

Transmembrane

domain

Nucleotide

binding

protein-protein

interaction, dimers

(3)

Protein domains present in

different types of R genes

Domain swaps between tomato

Cf-9 and Cf-4

identified

LRR as responsible of the

specificity of the pathogen

race....

... But in flax

L

gene is the

TIR domain

Protein

degradation

Zinc finger

Membrane

anchor

Recognition

specificity

(4)

Gen Especie Patógeno Avirulencia Tipo R-gen Referencia

N tabaco TMV replicasa TIR-NB-LRR Witham et al. 1994

Rps2 Arabidopsis Pseudomonas syringae AvrRpt2 CC-NB-LRR Bent et al. 1994

Rpp5 Arabidopsis Peronospora parasitica AvrRpp5 TIR-NB-LRR Parker et al., 1997

Mi tomate Meloidogyne incognita Macrosiphum euphorbia

- CC-NB-LRR Milligan et al., 1998

Tabla 3.1. Algunos ejemplos de R-genes del tipo NB-LRR activos frente a distintos grupos de patógenos. Se incluye un gen de resistencia activo frente a un virus, una bacteria, un hongo y un nemátodo. Adicionalmente el gen Mitambién confiere resistencia frente a un insecto. Se añade la avirulencia correspondiente si es conocida.

TMV: virus del mosaico del tabaco; Pseudomonas syringae: bacteria; Peronospora parasitica: hongo; Meloidogyne incógnita: nemátodo; Macrosiphum euphorbia: insecto

Gen Especie Patógeno Avirulencia Tipo R-gen Referencia

Pto tomate Pseudomonas syringaepv. tomato AvrPto Serina/treonina quinasa Martin et al. 1993

N tabaco TMV replicasa TIR-NB-LRR Witham et al. 1994

Rps2 Arabidopsis Pseudomonas syringae AvrRpt2 CC-NB-LRR Bent et al. 1994

Cf-9 tomate Cladosporium fulvum Avr9 eLRR-TM Jones et al. 1994

Xa21 arroz Xanthomonas oryzaepv. oryzae AvrXa21 eLRR-TM-quinasa Song et al., 1995

Ve1, Ve2

tomate Verticillium albo-atrum - CC-eLRR-TM eLRR-TM-PEST

Kawchuk et al. 2001

Rrs1 Arabidopsis Ralstonia solanacearum PopP2 NB-LRR-WRKY Deslandes et al. 2002

Rpw8 Arabidopsis Erysiphe cichoracearum - CC Xiao et al., 2001

Rpg1 cebada Puccinia graminisf. sp. tritici - Receptor quinasa Brueggeman et al. 2002

Tabla 3.2. Algunos ejemplos de distintos tipos de R-genes. Se incluye solamente un ejemplo para cada tipo de R-gen, además de algunos R-genes adicionales que presentan algunas particularidades estructurales que los diferencian de los grupos anteriores, como hemos comentado en el texto. Se añade la avirulencia correspondiente si es conocida.

TIR: Dominio ‘TOLL-Interleukin-1 resistance’; NB: dominio de unión a nucleótidos; LRR: repetición rica en leucina; CC: dominio coiled-coil; eLRR: repetición rica en leucina extracelular; PEST: dominio señal de degradación proteolítica; WRKY: dominio de unión a DNA

(5)

Melon BAC containing an NBS-LRR cluster

Gene

Homology

MRGH (7.5x)

TIR-NBS-LRR resistance genes

MRGH fragment (3x)

TIR-NBS-LRR resistance genes

WD-40

WD40 domain, signal transduction/pre-mRNA processing/cytoskeleton assembly

Dynamin

Dynamin GTPase domain, signalling proteins

Exostosin

Exostosin family, limonene cyclase, tumor suppressor genes

Unknown1

Hypothetical and unknown proteins rice and

A. thaliana

PDI (4x)

Thioredoxin domain, postranslational modification, protein turnover

Ulp1 (2x)

Ulp1 protease family, postranslational modification, protein turnover

PPR

Pentatricopeptide repeat protein, plants, RNA stabilisation/processing

RLK

Serine/Threonine protein kinase and legume lectins beta domain

RTP-Copia (3x)

Retrotransposable elements, Copia type, 2 full length, 1 fragment

LINE (3x)

LINE transposable elements, 1 full length, 2 fragments

(6)

Pathogen factor Host factor Pathogen factor Host factor

Recognition,

susceptibility

Pathogen factor Pathogen factor

No recognition,

resistance

Host factor Host factor

Recessive resistance genes

-

Do not follow gene-for-gene

-

Mutations in host genes

-

Necessary for susceptibility

-

Negative regulators of defence

(7)

• Genus

Carmovirus

, Family

Tombusviridae

• Transmitted by

Olpidium bornovanus

and

through the

seed

• Affects

cucurbit crop

species grown under

greenhouse

conditions

• Endemic

in cucurbit crops world-wide

• yield losses

(8)

Disease Control

• Certified seeds

• Control of fungal vector

• graffting melon in wattermelon

resistance stock

• Use of

genetic resistance

(restricted to melon, recessive

and monogenic gene:

nsv

)

(9)

MNSV-264

2 MNSV-M



5

2 MNSV-Dutch

1 Nsv/-(Susceptible)

nsv/nsv

(Resistant)

1 _{Rivière and Rochon (1990) J. Gen. Virol 71: 3033-3042}

2 _{Díaz et al (2004) MPMI 17: 668-675}

Isolation of MNSV strain that

(10)

7K20 14 1 1 5 1 1 2 2

M132

65

nsv

_D08

24O20 38B12 U 41I23 SP6 U 5A6 SP6 U 30L11 U SP6 34H17 5B3 U SP6 10G6 SP6 20E15 SP6 U 9N8 U 10O16 SP6 U 20F8b SP6 59I22b U SP6 5 2 1 0 4 0 34 52K20 SP6 100 kb 1-21-10 L R X 15 M 132 30L11s p6 5B 3sp 6 108 7 13 59

nsv

ns1 (M29)

ns2 (5A6sp6)

5A 6U 38B 12U

F2

BC1

Map-based cloning of major genes: the

nsv

locus

for resistance to MNSV

Morales et al. TAG (2006)

- Based on 3.000 F2 and

BC1 individuals

-

BAC libraries from

WMR29 and PIT92

(11)

Nieto et al. Plant J (2006)

Eukaryotic translation initation complex

nsv

is a mutant allele of the Cm-eIF4E gene

Co-bombardment of MNSV

and Cm-eIF4E in melon leaves

(12)

Study of complex traits: the melon NIL collection

• PI 161375 x T111

• 57 NILs

• Average

introgresion size: 47

cM (3.4% genome)

• Each linkage group

is represented by

4.75 NILs

• Genetic resolution:

49 bins, 18.9 cM/bin

• Subset of 28 NILs

cover the whole

genome

(13)

QTLs for fruit shape

Piel de sapo

_SC3-5

QTLs for fruit ripening

QTLs for CMV resistance

Genetic dissection of complex traits using

the melon genetic map and NILs

(14)

cmv1,

a recessive gene that confers

resistance to some CMV strains

Essafi et al. TAG (2008)

S

R

S

M730

S

R

S

FNY

S

R

S

TL

S

R

S

M6

R

S

R

S

LS

R

S

R

S

P104.82

R

S

R

S

P9

12-1

12-3

PI

161375

PS

Strains

R

S

-

Few sources of resistance to

CMV in melon. One of them in

PI 161375

- Oligogenic recessive (

Karchi

et al

, 1975

)

- Several QTLs detected in PI 161375,

with a major QTL in GLXII, common

to 3 CMV strains (

Dogimont

et al

, 2000

)

(15)

eIF candidate genes do not

map in the

cmv1

interval

A fine map of the

cmv1

region has been started

84.7 11.2 18.5 38.8 56.1 61.9 89.4 5A6U CSAT425A TJ29 CMTCN14 ECM105 CMN21_55 CMN61_44 PSI 22B02 CMAGN33 CMGAN80 ECM67 0 6.1 8.3