The root system of maize consists of the primary root and a variable number of lateral seminal-, crown- and brace roots. Except for the primary root and some minor roots forming at the mesocotyl, all other roots grow out of nodal regions, namely, the embryogenic scutellar node and the underground—as well as the lower above-ground stem nodes. Besides their role in water and nutrient uptake, some of these roots (crown- and brace roots) are essential for the lodging resistance of the plants. This property of the crown roots has now been successfully used for screening a segregating F2 population of a cross between a flint inbred line and an En transposon line. Two allelic root-deficient mutants have been isolated and have been designated rtcs-1 and rtcs-2 for their complete lack of formation of crown- and lateral seminal roots. They survive by the ability of the primary root to support the growth of the developing plant. The monogenic and recessive mutants appear to be affected in an early root-forming function since no primordia are formed either in the case of embryo-borne lateral seminal or stem-derived crown roots. The Rtcs locus could be mapped to the short arm of chromosome 1 with the help of a co-segregating RAPD marker. The effect of the mutation seems to be highly specific since no pleiotropic effects on other parts of the plants have been observed. The formation of adventitious roots can, however, still be induced in the mesocotyl region of the mutant.
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Document Type: Research Article
Institute of Biology III, University of Freiburg, Schänzlestr. 1, 79104 Freiburg, Germany
Südwestdeutsche Saatzucht, Im Rheinfeld 1–13, 76437 Rastatt, Germany
Publication date: November 1, 1996