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Changes in allelic frequencies in a tropical maize population under selection for drought tolerance

By: Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico DF (Mexico) | Ribaut, J.M.
Contributor(s): Edmeades, G.O [coaut.] | Edmeades, G.O.|Banziger, M.|Mickelson, H.R.|Peña-Valdivia, C.B [eds.] | González de León, D [coaut.] | Hoisington, D.A [coaut.] | Huerta-Espino, J [coaut.].
Material type: materialTypeLabelBookAnalytics: Show analyticsPublisher: Mexico, DF (Mexico) CIMMYT : 1997ISBN: 968-6923-93-4.Subject(s): Drought resistance | Drought stress AGROVOC | Flowering | Genetic inheritance | Plant population AGROVOC | Selection | Tropical zones | CIMMYT | Zea mays AGROVOCDDC classification: 633.153 Summary: Selection for grain yield under severe water stress has often been considered inefficient because heritability generally declines as yield is reduced while environmental variance remains the same or increases. Under these conditions selection for secondary traits correlated with yield, Such as the anthesis- silking interval (ASI), may increase selection efficiency. Although ASI is a simple trait to measure in the field and has a relatively high heritability, it is not always possible to provide the stress levels required for efficient selection of this trait. CIMMYT physiologists conducted eight cycles of full-sib recurrent selection during the dry season for drought tolerance in the population 'Tuxpeño Sequia' based mainly on an index comprising increased grain yield and reduced ASI. In this study, we quantified changes in allelic frequencies over cycles of selection at loci of known map position. Through these changes identification of alleles involved in the expression of short or long ASI was possible, and may provide a rapid diagnostic tool in the future for screening lines or plants with potential drought tolerance in Tuxpeño germplasm. Changes in allele frequencies over cycles of selection (C0, C4 and C8; 116 plants randomly chosen from each cycle) were estimated using molecular markers. Loci distributed over the maize genome were assayed using RFLPs. Special attention was given to genomic regions responsible for expression of ASI, identified in a previous study using a cross between two inbreds derived mainly from Tuxpeño germplasm. There is strong evidence that the alleles of these two inbred lines are also present in this population. Allelic frequencies that either increased, decreased or remained stable were recorded for C8 relative to C0. Some major allele frequency changes were detected at loci located in genomic regions responsible for ASI expression, and the effects of these frequency changes were estimated. Implications of this analysis concerning the improvement of open-pollinated populations or lines using molecular markers are discussed.Collection: CIMMYT Publications Collection
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Conference proceedings CIMMYT Knowledge Center: John Woolston Library

Lic. Jose Juan Caballero Flores

 

CIMMYT Publications Collection 633.153 EDM (Browse shelf) 1 Available 2T624179
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Selection for grain yield under severe water stress has often been considered inefficient because heritability generally declines as yield is reduced while environmental variance remains the same or increases. Under these conditions selection for secondary traits correlated with yield, Such as the anthesis- silking interval (ASI), may increase selection efficiency. Although ASI is a simple trait to measure in the field and has a relatively high heritability, it is not always possible to provide the stress levels required for efficient selection of this trait. CIMMYT physiologists conducted eight cycles of full-sib recurrent selection during the dry season for drought tolerance in the population 'Tuxpeño Sequia' based mainly on an index comprising increased grain yield and reduced ASI. In this study, we quantified changes in allelic frequencies over cycles of selection at loci of known map position. Through these changes identification of alleles involved in the expression of short or long ASI was possible, and may provide a rapid diagnostic tool in the future for screening lines or plants with potential drought tolerance in Tuxpeño germplasm. Changes in allele frequencies over cycles of selection (C0, C4 and C8; 116 plants randomly chosen from each cycle) were estimated using molecular markers. Loci distributed over the maize genome were assayed using RFLPs. Special attention was given to genomic regions responsible for expression of ASI, identified in a previous study using a cross between two inbreds derived mainly from Tuxpeño germplasm. There is strong evidence that the alleles of these two inbred lines are also present in this population. Allelic frequencies that either increased, decreased or remained stable were recorded for C8 relative to C0. Some major allele frequency changes were detected at loci located in genomic regions responsible for ASI expression, and the effects of these frequency changes were estimated. Implications of this analysis concerning the improvement of open-pollinated populations or lines using molecular markers are discussed.

Generation Challenge Program

English

9802|AGRIS 9702|anterior|R97-98PROCE|FINAL9798

Jose Juan Caballero

INT1991

CIMMYT Publications Collection

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