Regulation of Inflorescence Architecture and Organ Shape by the ERECTA Gene in Arabidopsis

Abstract

The architecture of higher plants is largely determined by the size,shape, and arrangement of the shoot organs that are formed in a reiterativemanner by the shoot apical meristem. Immense variations in plantarchitecture, due to altered shape, size, and position of the individualshoot unit, has significance in adaptation as well as domesticationof crop plants. The Arabidopsis erecta mutant displays a dramaticalteration in inflorescence architecture and organ shape. Morphometricanalysis of representative erecta alleles with different severitiesrevealed that ERECTA regulates pedicel length and plant size in aquantitative manner but has complex effects on floral organ size.The organs of erecta mutants contain a lesser number of larger, andisotropically expanded cortex cells, suggesting that ERECTA is requiredfor a coordinated cell proliferation or cell expansion within thesame tissue layer (i.e. cortex). The molecular identity of ERECTAas a leucine-rich repeat receptor-like kinase (LRR-RLK) is consistentwith its predicted role in cell-cell coordination.