Loss of an MDR Transporter in Compact Stalks of Maize br2 and Sorghum dw3 Mutants

• DOI: 10.1126/science.1086072
• Publication Date: 2003-10-02T20:43:16Z
• Authors: Dilbag S. Multani; Steven P. Briggs; Mark A. Chamberlin; Joshua J. Blakeslee; Angus S. Murphy; Gurmukh S. Johal
• Keywords: Recombination, Genetic; 2. Zero hunger; 0303 health sciences; ATP Binding Cassette Transporter, Subfamily B; Base Sequence; Indoleacetic Acids; Light; Plant Stems; Molecular Sequence Data; Biological Transport; Genes, Recessive; Genes, Plant; Poaceae; Zea mays; 03 medical and health sciences; Gene Duplication; Mutation; Amino Acid Sequence; Crossing Over, Genetic; Cloning, Molecular; Alleles; Plant Proteins

Agriculturally advantageous reduction in plant height is usually achieved by blocking the action or production of gibberellins. Here, we describe a different dwarfing mechanism found in maize brachytic2 ( br2 ) mutants characterized by compact lower stalk internodes. The height reduction in these plants results from the loss of a P-glycoprotein that modulates polar auxin transport in the maize stalk. The sorghum ortholog of br2 is dwarf3 ( dw3 ), an unstable mutant of long-standing commercial interest and concern. A direct duplication within the dw3 gene is responsible for its mutant nature and also for its instability, because it facilitates unequal crossing-over at the locus.