3rd Africa Rice Congress Theme 1: Climate resilient rice Mini symposium: towards improved resistance to biotic stresses Authors: Kolade et al.

1. Towards the identification of genetic
factors that control resistance of Oryza
glaberrima to Rice yellow mottle virus
Kolade O.A., J. Orjuela, G. Maillot, S. Chéron,
M.N. Ndjiondjop, A. Ghesquière and L. Albar

2. Introduction
Rice yellow mottle virus
First described in 1970
Endemic to Africa
Insect / mechanical transmission
Damages on high yielding varieties

3. Introduction contd.
Susceptibility
O. sativa indica
O. glaberrima
High resistance
O. sativa : 2 accessions, 1 resistance source
Gigante
RYMV1 (allele -2)
Bekarosaka
High resistance
O. sativa indica
O. glaberrima
Partial resistance
O. sativa japonica
O. glaberrima : at least 29 accessions and 5
independent resistance sources
Tog5681
Tog5674
RYMV1 (alleles -3, -4, -5)
Tog5672
RYMV2
Tog7291
Tog5307

4. Introduction contd.
Susceptibility
O. sativa indica
O. glaberrima
High resistance
O. sativa : 2 accessions, 1 resistance source
Gigante
RYMV1 (allele -2)
Bekarosaka
High resistance
O. sativa indica
O. glaberrima
Partial resistance
O. sativa japonica
RYMV1 encodes eIF(iso)4G
resistance conferred by point mutations
MAS on rymv1-2
O. glaberrima : at least 29 accessions and 5
independent resistance sources
Tog5681
Tog5674
RYMV1 (alleles -3, -4, -5)
Tog5672
RYMV2
Tog7291
Tog5307

5. Introduction contd.
Susceptibility
O. sativa indica
O. glaberrima
High resistance
O. sativa : 2 accessions, 1 resistance source
Gigante
RYMV1 (allele -2)
Bekarosaka
High resistance
O. sativa indica
O. glaberrima
Partial resistance
O. sativa japonica
RYMV2 probably encodes CPR5-1
resistance allele = null allele
RYMV2-CPR5-1 alone is not sufficient
to confer resistance in IR64
O. glaberrima : at least 29 accessions and 5
independent resistance sources
Tog5681
Tog5674
RYMV1 (alleles -3, -4, -5)
Tog5672
RYMV2
Tog7291
Tog5307

6. Objectives
A better characterization of RYMV2 mediated resistance
 Diversity on RYMV2 candidate gene
 research of locus interacting with RYMV2 to confer
resistance
Genetic basis of Tog5307 resistance

7. Diversity on RYMV2 candidate gene

8. Diversity on RYMV2 candidate gene
agarose
QIAXCEL analyser
 Analysis of CAPS/CPR5-1 on a
collection of rice accessions

9. Diversity on RYMV2 candidate gene
No of accessions
60
Alleles
50
40
30
Tog7291 and
6 resistant
accessions
20
10
0
O. sativa
(56 Acc.)
O. barthii
(107 Acc.)
O. glabberima
(241 Acc.)
206-208
213
223
232
244
deletion

10. Research of additional loci involved in Tog7291 resistance
Test of statistical associations between candidate loci and resistance
 BC1-F3 [(Tog7291 x IR64) x Tog7291] population
 14 F3 families fixed for CPR5-1 (RR) and in segregation for resistance
 QTLs or candidate gene regions
Tog7291
allele
Htz
IR64
allele
 Putative impact of the region containing
CPR5-2 gene on Tog7291 resistance

11. Genetic basis of Tog5307 resistance
Tog7291 x Tog5307
F2
F3 families in segregation for
Tog7291 and Tog5307
resistance
F3:191R/153S (p>0.05 for 1 dom.gene)
Selection of F2 without
Tog7291 resistance
F3(R) x F3(S)
Pseudo-F2 &
pseudo-F3 families
Tog5307’s resistance
dominant
F2: 62R/20S (p>0.05 for 1 dom. gene)
F3: 265R/141S (p>0.05 for 1 dom.gene)

12. Conclusions
• CAPs marker CPR5-1 showed higher diversity in
African species
• CPR5-1 and CPR5-2 maybe interacting to confer
resistance
• Tog5307’s resistance is dominant and oligogenic
• Pyramiding of these genes : a very promising
solution for durable RYMV resistance

13. Acknowledgements
• ALL IRD DIADE TEAM: DR ALBAR AND DR
ALAIN GHESQUIERE
• ALL AFRICA RICE BIOTECHNOLOGY TEAM
:DR NDJIONDJOP