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Genetic analysis of heat tolerance will help breeders produce rice ( Oryza sativa L.) variet-ies adapted to future climates. An F 6 population of 181 recombinant of Aberdeen, Aberdeen, AB24 3UU, UK. J. Cairns, current address: inbred lines of Bala (toler-ant) × Azucena (susceptible) was screened for heat tolerance at anthesis by measuring spikelet fertility at 30°C (control) and 38°C (high temper-ature) in experiments conducted in the Philip-pines and the United Kingdom. The parents varied significantlyfor absolute spikelet fertility under control (79–87%) and at high tempera-ture (2.9–47.1%), and for relative spikelet fertility (high temperature/control) at high temperature (3.7–54.9%). There was no correlation between spikelet fertility in control and high-temperature conditions and no common quantitative trait loci (QTLs) were identified.Two QTLs for spike-let fertility under control conditions were identi-fiedon chromosomes 2 and 4. Eight QTLs for spikelet fertility under high-temperature condi-tions were identifiedon chromosomes 1, 2, 3, 8, 10, and 11. The most significantheat-responsive QTL, contributed by Bala and explaining up to 18% of the phenotypic variation, was identifiedon chromosome 1 (38.35 mega base pairs on the rice physical genome map). This QTL was also found to influenceplant height, explain-ing 36.6% of the phenotypic variation. A com-parison with other studies of abiotic (drought, cold, salinity) stresses showed QTLs at similar positions on chromosomes 1, 3, 8, and 10, sug-gesting common underlying stress-responsive regions of the genome.S.V.K. Jagadish, T.R. Wheeler, and P.Q. Craufurd, Plant Environment Lab., Univ. of Reading, Cutbush Lane, Shinfield, Reading, RG2 9AF, UK; J. Cairns and R. Lafitte, Crop and Environmental Sciences Divi-sion, International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines; A.H. Price, Dep. of Plant and Soil Science, Univ. CIMMYT, Km. 45, Carretera Mexico-Veracruz, El Batan, Texcoco, Edo. de Mexico, CP 56130, Mexico. Received 18 Sept. 2009. *Cor-responding author (p.craufurd@cgiar.org). |
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