Genetic analysis of root traits in maize

In many areas around the world, maize (Zea Mays L.) crops are affected by root lodging. Several authors have previously shown that associations of root and shoot traits enabled the prediction of the resistance of genotypes to root lodging. In this preliminary attempt to understand the genetics of these traits, a set of 100 recombinant inbred lines from a cross between lite lines 'F2' (early, susceptible to root lodging) and 'Io' (late, lodging resistant) was considered. This population was characterised for 152 RFLP loci and root system traits in one location and for 2 years. QTLs were mapped using the average over years. Genetic and environmental correlations, together with co-localisation of QTLs for several traits, revealed genetic linkages, and some probable pleiotropic effects, which could be interpreted in terms of within-plant growth competition phenomena. The identification, on chromosome 5, of groups of loci involved in the con- trol of the growth of the root system could help select against root lodging. ( © Inra/Elsevier, Paris.) Zea mays L. / root lodging / pleitropic effect / linkage effect / QTL Rsum -Analyse gntique des caractres racinaires du mas. Dans de nombreuses rgions du monde, la verse en vgtation peut porter prjudice la rentabilit de la culture de mas. Plusieurs auteurs ont mis en vidence que des caractristiques ariennes et racinaires, considres ensemble, sont dterminantes dans la variation de la rsistance. Dans une premire approche, les caractres impliqus dans la rsistance la verse sont analyss gntiquement dans un lieu sur deux annes, partir de 100 lignes recombinantes issues du croisement de 'F2' et 'Io'. l'aide de 152 marqueurs RFLP, les QTL sont recherchs sur la moyenne des deux annes. partir des corrlations gntiques et environ- nementales ou partir de la co-localisation des QTL, des linkages et des effets pliotropiques entre les caractres sont rvls. La mise en vidence, sur le chromosome 5, de groupes de locus impliqus dans la croissance du systme raci- naire pourrait faciliter la slection de gnotypes rsistants la verse en vgtation. ( © Inra/Elsevier, Paris.)