Mapping quantitative trait loci for grain quality traits in rice under high temperature stress
2012
Apolinario, Ma. A.L.L.
A F sub 2 mapping population of 119 lines derived from the cross between a heat tolerant donor, IR6-Pakistan, and heat susceptible variety, NSIC Rc 158 was generated to identify QTL associated with heat tolerance at the grain filling stage in rice. The plants were exposed to high temperature (38 deg C) five days after flowering up to maturity. One hundred grain weight was determined, and using this data heat susceptibility index (HSI) was calculated to identify heat resistant (HSI less than 1) and heat sensitive (HS1 greater than 1) lines. A total of 205 SSR markers distributed across the 12 chromosomes were used to determine polymorphisms between the two parents. Seventy five polymorphic markers were identified, however, only 45 were used in mapping heat tolerant QTLs. Data was analyzed using Windows QTL Cartographer version 2.5. Using a single marker analysis, QTLs associated with grain chalkiness were detected on chromosomes 3 and 8 while regions with significant P values for gelatinization temperature (GT) were located on chromosomes 2,5,9 and 12 were likely linked to QTL. The results of the simple interval mapping reavealed QTL associated with grain chalkiness and GT were both located on chromosome 3. Composite interval mapping revealed QTLs associated with grain chalkiness on chromosomes 1, 3 and 7. QTLs located on chromosomes 5 and 6 were associated to gelatinization temperature. These results could be useful in the development of the heat tolerant rice varieties during the grain filling stage.
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