Mapping genes controlling root morphology and root distribution in a doubled-haploid population of rice |
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Authors: | R Yadav B Courtois N Huang G McLaren |
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Institution: | (1) International Rice Research Institute, P.O. Box 933, Manila, The Philippines, XX |
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Abstract: | A deep thick root system has been demonstrated to have a positive effect on yield of upland rice under water stress conditions.
Molecular-marker-aided selection could be helpful for the improvement of root morphological traits, which are otherwise difficult
to score. We studied a doubled-haploid population of 105 lines derived from an indica×japonica cross and mapped the genes controlling root morphology and distribution (root thickness, maximum root length, total root
weight, deep root weight, deep root weight per tiller, and deep root to shoot ratio). Most putative QTL activity was concentrated
in fairly compact regions on chromosomes 1, 2, 3, 6, 7, 8 and 9, but was widely spread on chromosome 5 and largely absent
on chromosomes 4, 10, 11 and 12. Between three and six QTLs were identified on different chromosomes for each trait. Individual
QTLs accounted for between 4 and 22% of the variation in the traits. Multiple QTL models accounted for between 14 and 49%.
The main QTLs were common between traits, showing that it should be possible to modify several aspects of root morphology
simultaneously. There was evidence of interaction between marker locations in determining QTL expression. Interacting locations
were mostly on different chromosomes and showed antagonistic effects with magnitudes large enough to mask QTL detection. The
comparison of QTL locations with another population showed that one to three common QTLs per trait were recovered, among which
the most significant was in one or other population. These results will allow the derivation of isogenic lines introgressed
with these common segments, separately in the indica and japonica backgrounds.
Received: 12 August 1996 / Accepted: 15 November 1996 |
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Keywords: | Upland rice Doubled-haploid lines Root morphology Molecular markers QTL analysis |
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