Application of Molecular Markers to Rice Breeding in Vietnam

News source: Department of Agriculture and Forestry Extension, MARD, Vietnam
For further information, see Science & Technology Journal of Agriculture and
Rural Development., 2003-10-01

Molecular Markers for Pest and Disease Resistance

Molecular markers have several advantages over traditional phenotypic markers in terms of improving the efficiency of conventional plant breeding. Molecular markers applied in rice breeding in the Mekong Delta have been implemented since 1996 for some major biotic stresses [brown planthopper (BPH), bacterial leaf blight (BLB)] as well as for the analysis of genetic diversity of rice germplasm.

Four Genetic Clusters in Meking Delta Based on Morphology

Through the analysis of genetic diversity of rice and its relatives in the Mekong Delta, four genetic clusters were identified by Tocher and Mahalonobis' methods based on morphological traits. Floating rice (cluster I) was found to be close to the wild rice species Oryza rupifogon. Cluster II included local rice accessions collected from coastal areas with salt tolerance, while Cluster III included deep water rice collected from the western region. Cluster IV, on the other hand, was composed of early-monsoon rice cultivars without photosensitivity.

Two Major Clusters Based on Dna

Rice germplasm was classified into two major clusters and many subclusters by Random Amplified Polymorphism DNA (RAPD). Sequence tagged site markers (STS) were used to detect resistant genes for BPH and BLB. Most of the traditional cultivars were considered as good sources of genes Pi-2, Xa-5, and Xa-13. Two pairs of primer RG 457 were designed as STS markers digested with Hinff and Alul to be useful for detecting BHP resistant genes to biotypes 2 and 3. The PCR-based markers showed that the resistant genotypes had 500, 300 bp bands and 300, 250, 200 bp bands in primers RG 457 FL/RB and RG 457 FL/RL, respectively.

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