Experimental evaluation of several cycles of marker-assisted selection in maize |
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| Authors: | L Moreau A Charcosset A Gallais |
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| Institution: | (1) INRA-UPS-INAPG-CNRS, Station de génétique végétale, Ferme du Moulon, 91190 Gif-sur-Yvette, France |
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| Abstract: | A program was initiated in 1994 to compare the efficiency of marker-assisted selection (MAS) and conventional phenotypic selection.
A population of 300 F3:4 families was generated from the cross between two maize inbred lines F2 and F252 and selected on an index combining grain yield and grain moisture at harvest. This population was characterised for 93 RFLP
markers and evaluated as testcrosses in a large range of environments. Three methods of selection were applied (i) two cycles
of conventional phenotypic selection; (ii) two cycles of MAS based on an index combining phenotypic values and QTL genetic
values and (iii) one cycle of combined MAS followed by two cycles of selection based only on the QTL effects estimated in
the first generation. The different populations were characterised for RFLP markers. The evolution of allele frequencies showed
that selection on only-markers was very efficient for fixing QTL alleles found favourable in the initial population. This
evolution was quite different from that observed for phenotypic selection or combined MAS. Genetic gain was evaluated and
found significant for each method of selection. Nevertheless, the difference between phenotypic selection and combined MAS
was not significant. The two additional cycles of MAS on only-markers did not improve significantly the genetic value of the
population. Moreover, the genetic variance of this population remained high, despite most of the QTL initially detected were
almost fixed. The results suggest that the QTL effects estimated in the initial population were not stable due to epistasis
and/or QTL by environment interactions.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | grain moisture grain yield maize marker-assisted selection QTL |
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