Abstract
Blast is the most common biotic stress leading to the reduction of rice yield in many rice-growing areas of the world, including Malaysia. Improvement of blast resistance of rice varieties cultivated in blast endemic areas is one of the most important objectives of rice breeding programs. In this study, the marker-assisted backcrossing strategy was applied to improve the blast resistance of the most popular Malaysian rice variety MR219 by introgressing blast resistance genes from the Pongsu Seribu 2 variety. Two blast resistance genes, Pi-b and Pi-kh, were pyramided into MR219. Foreground selection coupled with stringent phenotypic selection identified 15 plants homozygous for the Pi-b and Pi-kh genes, and background selection revealed more than 95% genome recovery of MR219 in advanced blast resistant lines. Phenotypic screening against blast disease indicated that advanced homozygous blast resistant lines were strongly resistant against pathotype P7.2 in the blast disease endemic areas. The morphological, yield, grain quality, and yield-contributing characteristics were significantly similar to those of MR219. The newly developed blast resistant improved lines will retain the high adoptability of MR219 by farmers. The present results will also play an important role in sustaining the rice production of Malaysia.
Highlights
The rice production system makes a vital contribution to the reduction of hunger and poverty
The present study suggests that DNA markers for blast resistance genes are reliable for marker-assisted selection of blast resistance in rice breeding
These improved blast resistant lines could be utilized as a source of genetic material for blast resistance with a high yielding background of MR219
Summary
The rice production system makes a vital contribution to the reduction of hunger and poverty. The fast growth of the world population demands an increase of 26% in rice production to fulfill the requirement (Khush, 2013). Rice production has widely increased after the green revolution, but the yield of superior varieties is still not increasing as farmers expect due to the influence of biotic and abiotic factors (Divya et al, 2014). The continuous supply of rice per demand of the consumer can only be achieved by maintaining a stable rice production, which is a challenge for rice breeders (Roychowdhury et al, 2012). Rice production can be managed by introducing new varieties possessing strong resistance against abiotic and biotic factors.
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