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Re-evaluation of the prospects of marker-assisted selection for improving insect resistance against diatraea spp. in tropical maize by cross validation and independent validation

By: Contributor(s): Material type: ArticleArticlePublication details: 2001ISSN:
  • 1432-2242 (Revista en electrónico)
Subject(s): In: Theoretical and Applied Genetics v. 103, no. 6-7, p. 1059-1067630875Summary: Cross validation (CV) and validation with an independent sample (IV) are new biometric approaches in QTL analysis to obtain unbiased estimates of QTL effects and the proportion of the genetic variance ex- plained by the detected marker-QTL association (p). Our objective with these methods was to obtain a realistic picture on the prospects of marker-assisted selection (MAS) for improving the resistance of maize against the tropical stem borer species Diatraea grandiosella (SWCB) and Diatraea saccharalis (SCB). Published QTL mapping studies on leaf-damage ratings (LDR) with populations of F2:3 lines and recombinant inbred lines (RIL) from crosses CML131xCML67 and Ki3x CML139 of tropical maize inbreds were re-analyzed with CV and IV. With CV, the reduction in p for LDR compared to p obtained with the whole data set varied between 41.0 and 79.6% in the populations of F2:3 lines and between 30.1 and 65.2% in the two populations of RIL. Estimates of p for SCB LOR were similar for CV and IV. For SWCB LOR, p estimates obtained with IV were larger than those obtained with CV in CML 131xCML67. The reverse was observed for Ki3xCML139. Under the assumption of identical selection intensities, and based on the re-estimates of p, MAS using only molecular marker information is less-efficient than conventional phenotypic selection (CPS). MAS combining marker and phenotypic data increases the relative efficiency by only 4% in comparison to CPS. In conclusion, MAS for improving SWCB and SCB LDR seems notpromising unless additional QTLs with proven large effects are available or the costs of marker assays are considerably reduced.
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Peer-review: Yes - Open Access: Yes|http://science.thomsonreuters.com/cgi-bin/jrnlst/jlresults.cgi?PC=MASTER&ISSN=0040-5752

Cross validation (CV) and validation with an independent sample (IV) are new biometric approaches in QTL analysis to obtain unbiased estimates of QTL effects and the proportion of the genetic variance ex- plained by the detected marker-QTL association (p). Our objective with these methods was to obtain a realistic picture on the prospects of marker-assisted selection (MAS) for improving the resistance of maize against the tropical stem borer species Diatraea grandiosella (SWCB) and Diatraea saccharalis (SCB). Published QTL mapping studies on leaf-damage ratings (LDR) with populations of F2:3 lines and recombinant inbred lines (RIL) from crosses CML131xCML67 and Ki3x CML139 of tropical maize inbreds were re-analyzed with CV and IV. With CV, the reduction in p for LDR compared to p obtained with the whole data set varied between 41.0 and 79.6% in the populations of F2:3 lines and between 30.1 and 65.2% in the two populations of RIL. Estimates of p for SCB LOR were similar for CV and IV. For SWCB LOR, p estimates obtained with IV were larger than those obtained with CV in CML 131xCML67. The reverse was observed for Ki3xCML139. Under the assumption of identical selection intensities, and based on the re-estimates of p, MAS using only molecular marker information is less-efficient than conventional phenotypic selection (CPS). MAS combining marker and phenotypic data increases the relative efficiency by only 4% in comparison to CPS. In conclusion, MAS for improving SWCB and SCB LDR seems notpromising unless additional QTLs with proven large effects are available or the costs of marker assays are considerably reduced.

English

0112|Springer|AGRIS-0103|AL-ABC Program|R01JOURN|3

Juan Carlos Mendieta

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