Mutations in the eIF(iso)4G translation initiation factor confer high resistance of rice to Rice yellow mottle virus.

We report here evidence of the role that the isoform of the eukaryotic translation initiation factor 4G (eIF(iso)4G) plays in naturally occurring resistance in plant/virus interactions. A genetic and physical mapping approach was developed to isolate the Rymv1 locus controlling the high recessive resistance to Rice yellow mottle virus (RYMV) in the rice (Oryza sativa) variety Gigante. The locus was mapped to a 160-kb interval containing a gene from the eIF(iso)4G family.

The population structure of African cultivated rice oryza glaberrima (Steud.): evidence for elevated levels of linkage disequilibrium caused by admixture with O. sativa and ecological adaptation.

Genome-wide linkage disequilibrium (LD) was investigated for 198 accessions of Oryza glaberrima using 93 nuclear microsatellite markers. Significantly elevated levels of LD were detected, even among distantly located markers. Free recombination among loci at the population genetic level was shown (1) by a lack of decay in LD among markers on the same chromosome and (2) by a strictly increasing composite likelihood function for the recombination parameter.

Mapping QTLs associated with drought avoidance in upland rice grown in the Philippines and West Africa.

Localizing genes that contribute to drought avoidance in a quantitative way should enable the exploitation of these genes in breeding through marker-assisted selection, and may lead to the discovery of gene identity and function. Between 110 and 176 F6 recombinant inbred lines from a mapping population derived from a cross of upland rice varieties Bala and Azucena have been evaluated for indicators of drought avoidance in sites in the Philippines and West Africa over two dry seasons. A molecular map with 102 RFLP, 34 AFLP and six microsatellite markers has been used to map (by composite interval mapping) quantitative trait loci (QTLs) for the visual scores of leaf rolling and leaf drying and leaf relative water content.