Doebley J, Stec A, Hubbard L
Department of Plant Biology, University of Minnesota, St Paul 55108, USA.
Nature. 1997 Apr 3;386(6624):485-8. doi: 10.1038/386485a0.
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.
农作物的驯化过程通常伴随着顶端优势的增强（即资源集中于植物的主茎，同时相应抑制腋芽分支）。这种现象的一个显著例子见于玉米（Zea mays spp. mays），与它可能的野生祖先大刍草（Zea mays ssp. parviglumis）相比，玉米的顶端优势显著增强。先前的研究已确定玉米分枝1（tb1）基因是导致玉米这一进化变化的主要因素。我们通过转座子标签法克隆了tb1基因，在此表明它编码一种与金鱼草的cycloidea基因具有同源性的蛋白质。tb1基因的表达模式以及tb1突变体植株的形态表明，tb1基因既抑制腋生器官的生长，又促使雌花序的形成。tb1基因的玉米等位基因的表达水平是大刍草等位基因的两倍，这表明基因调控变化是玉米与大刍草进化分化的基础。
