The evolution of apical dominance in maize

Abstract

The domestication of crop plants has often involved an increase in apical dominance (the concentration of resources in the main stem of the plant and a corresponding suppression of axillary branches). A striking example of this phenomenon is seen in maize (Zea mays spp. mays), which exhibits a profound increase in apical dominance compared with its probable wild ancestor, teosinte (Zea mays ssp. parviglumis). Previous research has identified the teosinte branched1 (tb1) gene as a major contributor to this evolutionary change in maize. We have cloned tb1 by transposon tagging and show here that it encodes a protein with homology to the cycloidea gene of snapdragon. The pattern of tb1 expression and the morphology of tb1 mutant plants suggest that tb1 acts both to repress the growth of axillary organs and to enable the formation of female inflorescences. The maize allele of tb1 is expressed at twice the level of the teosinte allele, suggesting that gene regulatory changes underlie the evolutionary divergence of maize from teosinte.

Evolution of flower shape in Plantago lanceolata

“…CYC-like genes are not expressed in inflorescence tissue in related Antirrhineae species. However, in maize the CYC-like gene TB1 affects internode length in the inflorescence, as well as suppressing axillary bud growth (Doebley et al 1997). Constitutive expression of TB1 in wheat has the generalized effect of reducing internode length in transgenic plants, and affects inflorescence architecture by reducing internode length on mature spikes, giving rise to more compact inflorescences than in wild-type plants (Lewis et al 2008).…”

TheArabidopsis thalianaTCP transcription factors: A broadening horizon beyond development

“…[1][2][3] This protein family is represented by 4 founding members, including TEOSINTE BRANCHED1 (TB1), CYCLOIDEA (CYC), PROLIFERATING CELL NUCLEAR ANTIGEN FACTOR1 (PCF1) and PCF2, which are identified on the basis of either their functions in plant development or their DNA binding capacities. [4][5][6][7][8] Whereas TB1 suppresses lateral branching in maize (Zea mays) and CYC controls floral dorsoventral asymmetry in snapdragon (Antirrhinum majus), PCF1 and PCF2 promote cell proliferation and organ growth in rice (Oryza sativa). [4][5][6][7][8] According to the differential features within the plant-specific TCP domain, TCP proteins can be distinguished into 2 divergent types, including the class I (TCP-P) and class II (TCP-C), and the latter is further divided into 2 subgroups, namely ubiquitous CINCINNATA (CIN) and angiosperm-specific CYC/TB1.…”

“…[4][5][6][7][8] Whereas TB1 suppresses lateral branching in maize (Zea mays) and CYC controls floral dorsoventral asymmetry in snapdragon (Antirrhinum majus), PCF1 and PCF2 promote cell proliferation and organ growth in rice (Oryza sativa). [4][5][6][7][8] According to the differential features within the plant-specific TCP domain, TCP proteins can be distinguished into 2 divergent types, including the class I (TCP-P) and class II (TCP-C), and the latter is further divided into 2 subgroups, namely ubiquitous CINCINNATA (CIN) and angiosperm-specific CYC/TB1. 2,9 Interestingly, TCP proteins have in common a short a-helical L**LL motif located in the second helix of the DNA-binding domain.…”

A TCP domain transcription factor controls flower type specification along the radial axis of the Gerbera (Asteraceae) inflorescence

“…TB1 has played a major role in the evolution of maize from its wild ancestor teosinte. It acts as a repressor of growth by suppressing axillary branching, and thus promotes apical dominance in domesticated maize (17). TB1 homologs have also been shown to prevent the growth of axillary buds in rice and Arabidopsis (15,18).…”