Friday, March 11, 2011

Postdoc research: Improvement of rice yield through molecular breeding

This research was conducted to identify possible trait enhancing quantitative trait loci (QTLs) from common wild rice, Oryza rufipogon. Two hundred and sixty-six BC2F2 families were developed from an interspecific cross between O. rufipogon accession no. IRGC 105491 and O. sativa cv. ‘MR219’during 2002-2003. Field evaluation of the BC2F2 families for 18 yield and yield related traits was carried out in 2004 at Malaysian Agricultural Research and Development Institute, Seberang Perai. Ninety three SSR (simple sequence repeat) markers were used to create a genetic linkage map spanning the twelve rice chromosomes. Ninety one QTLs were detected by means of marker regression with a significance level of p < 0.01. Among the putative QTLs, 21 were significant and 70 were suggestive. QTLs having favourable effects were noticed for days to heading (decrease heading period up to 6%), grain filling (increased filled grains plant-1 up to 12%), grain yield (increased grain yield plant-1 up to 10%), resistance to bacterial leaf blight (increased resistance by 13%), and tolerance to brown planthopper infection (increased tolerance by 40%). Quantitative data analysis suggests that about 10% of the total of 266 BC2F2 families demonstrated nearly 27% higher yield potential in comparison to the parental cultivar ‘MR219’. This increase is mostly due to higher tillering ability which is characteristic of O. rufipogon. These families also showed a considerable increase in tolerance against bacterial leaf blight and brown plant hopper infestation. The selected BC2F2 families can offer an efficient source of genetic diversity for future breeding programmes. The study concludes that even though wild rice is inferior to most of the agronomic traits, they could positively contribute to the overall yield enhancement in cultivated rice.

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