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Volume 47, Issue 2 p. 507-516
Crop Breeding & Genetic

A Large-Effect QTL for Grain Yield under Reproductive-Stage Drought Stress in Upland Rice

Jérôme Bernier

Jérôme Bernier

International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines

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Arvind Kumar

Arvind Kumar

International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines

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Venuprasad Ramaiah

Venuprasad Ramaiah

International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines

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Dean Spaner

Dean Spaner

Univ. of Alberta, Edmonton, AB, Canada, T6G 2R3

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Gary Atlin

Corresponding Author

Gary Atlin

International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines

Corresponding author ([email protected]).Search for more papers by this author
First published: 01 March 2007
Citations: 337

ABSTRACT

Genetic control of yield under reproductive-stage drought stress was studied in a population of 436 random F3–derived lines from a cross between the upland rice (Oryza sativa L.) cultivars Vandana and Way Rarem. Screening was conducted under upland conditions at IRRI during the dry seasons of 2005 and 2006. Lines were evaluated in drought stress and nonstress trials in both years to identify QTL contributing to drought resistance. For QTL detection, a set of random lines and the highest and lowest-yielding lines under both stress and nonstress conditions were genotyped by 126 SSR markers. A QTL (qtl12.1) with a large effect on grain yield under stress was detected on Chromosome 12 in both years. The whole population was genotyped for additional markers on Chromosome 12, allowing QTL localization to a 10.2 cM region between SSR markers RM28048 and RM511. Under stress conditions, the locus also increased harvest index, biomass yield, and plant height while reducing the number of days to flowering. Under nonstress conditions, qtl12.1 did not significantly affect any trait. The additive effect of this QTL on grain yield under stress was 172 kg ha−1 per year over the 2 yr of testing, representing 47% of the average yield under stress and explaining 51% of the genetic variance. The yield-increasing allele was derived from the susceptible parent, Way Rarem, suggesting an epistatic effect. This is the first QTL reported in rice having a large and repeatable effect on grain yield under severe drought stress in the field.