Markers for fine-mapping of quantitative trait loci (QTL) for rice (Oryza sativa L.) crack resistance
2017
Dalusong, V.G. | Mallan, R.P. | Mananghaya, T.E. | Alvariño, J.B.M. | Tuaño, A.P.P. | Perez, L.M. | Juliano, B.O.
Grain characteristics, milling quality and head rice recovery are important factors affecting worldwide agripreneurs' profitability and marketability of rice varieties. Grain cracking or fissuring caused by factors such as hull tightness and bran diffusitivity, environmental, mechanical and genetics, compromises the quality of milled rice. Efforts in study of genetic mechanism for rice crack resistance is in progress, wherein, seven putative QTLs located on chromosomes 2, 3 and 7 were identified from genotype-phenotype linkage analysis of the mapping population derived from the cross between PSB Rc52 (crack resistant) and NSIC Rc160 (susceptible) (Dalusong et. al, unpublished). The size of the putative QTL regions were 20 Mb on chromosome 2, 28 Mb on chromosome 3 and 10 Mb on chromosome 7. The regions within and on the 3 Mb upstream and downstream the flanking markers of the QTLs were saturated using 905 Simple Sequence Repeat (SSR) markers with one marker per 1 Mb interval. The graphical genotype was constructed using GGT 2.0: Genotyping to visualize the coverage and position of the markers. Results of screening obtained 86 polymorphic SSR markers on chromosome 2, 49 on chromosome 3 and 42 on chromosome 7 with a total of 177. The identified polymorphic SSR markers are being used to fine-mapped the position of crack resistance QTL. Once located the region will be isolated, cloned and characterized. This study is very important in finding the gene responsible for the resistance of the rice grain to cracking or fissuring for future use in breeding of rice varieties with increased head rice recovery.
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