Molecular breeding of rice drought tolerance
Water deficit is an increasingly important constraint limiting rice production, highlighting the need for varieties with improved drought tolerance and technologies that increase water-use efficiency. Drought tolerance, however, is a complex character resulting from the interaction of many quantitative component traits. Marker-based genetic studies permitted the identification of reliable QTLs for root traits and osmotic adjustment. To demonstrate the value of marker-aided selection to manipulate QTLs, we describe two examples of introgression of QTLs into elite material undertaken in the framework of an upland rice breeding program. The first study targeted root depth. Several QTLs from Azucena, a deep-rooted variety, were introgressed into IR64 through three cycles of backcrosses with selection based on marker information alone. The evaluation of the BC3 F3 families showed what progress could be expected and how progress was affected by lack of precision in QTL positions. For the second study, targeting osmotic adjustment, we used the advanced backcross QTL analysis method, which allows the simultaneous discovery and transfer of interesting QTLs, a procedure that appeared more adapted to a breeding program. We transferred QTLs for osmotic adjustment from IR62266, an indica donor, into IR60080-46A, a japonica elite line, conducted QTL analysis in a BC3F3 population, and outlined a strategy to construct improved near-isogenic lines. The candidate gene approach was used to associate genes with QTLs in this population. Association studies based on linkage disequilibrium in breeders' working collections could allow further progress by locating QTLs more precisely.
| Main Authors: | , , , , , |
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| Format: | conference_item biblioteca |
| Language: | eng |
| Published: |
IRRI
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| Subjects: | F30 - Génétique et amélioration des plantes, Oryza, résistance à la sécheresse, amélioration des plantes, génétique moléculaire, marqueur génétique, racine, http://aims.fao.org/aos/agrovoc/c_5435, http://aims.fao.org/aos/agrovoc/c_2392, http://aims.fao.org/aos/agrovoc/c_5956, http://aims.fao.org/aos/agrovoc/c_27577, http://aims.fao.org/aos/agrovoc/c_24030, http://aims.fao.org/aos/agrovoc/c_6651, |
| Online Access: | http://agritrop.cirad.fr/519129/ |
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| Summary: | Water deficit is an increasingly important constraint limiting rice production, highlighting the need for varieties with improved drought tolerance and technologies that increase water-use efficiency. Drought tolerance, however, is a complex character resulting from the interaction of many quantitative component traits. Marker-based genetic studies permitted the identification of reliable QTLs for root traits and osmotic adjustment. To demonstrate the value of marker-aided selection to manipulate QTLs, we describe two examples of introgression of QTLs into elite material undertaken in the framework of an upland rice breeding program. The first study targeted root depth. Several QTLs from Azucena, a deep-rooted variety, were introgressed into IR64 through three cycles of backcrosses with selection based on marker information alone. The evaluation of the BC3 F3 families showed what progress could be expected and how progress was affected by lack of precision in QTL positions. For the second study, targeting osmotic adjustment, we used the advanced backcross QTL analysis method, which allows the simultaneous discovery and transfer of interesting QTLs, a procedure that appeared more adapted to a breeding program. We transferred QTLs for osmotic adjustment from IR62266, an indica donor, into IR60080-46A, a japonica elite line, conducted QTL analysis in a BC3F3 population, and outlined a strategy to construct improved near-isogenic lines. The candidate gene approach was used to associate genes with QTLs in this population. Association studies based on linkage disequilibrium in breeders' working collections could allow further progress by locating QTLs more precisely. |
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