Plant Gene Expression Center/USDA, University of California, Berkeley, Albany, CA, 94710, USA.
Brigham Young University, Provo, UT, 84602, USA.
Nat Commun. 2019 Aug 23;10(1):3810. doi: 10.1038/s41467-019-11774-w.
Many domesticated crop plants have been bred for increased apical dominance, displaying greatly reduced axillary branching compared to their wild ancestors. In maize, this was achieved through selection for a gain-of-function allele of the TCP transcription factor teosinte branched1 (tb1). The mechanism for how a dominant Tb1 allele increased apical dominance, is unknown. Through ChIP seq, RNA seq, hormone and sugar measurements on 1 mm axillary bud tissue, we identify the genetic pathways putatively regulated by TB1. These include pathways regulating phytohormones such as gibberellins, abscisic acid and jasmonic acid, but surprisingly, not auxin. In addition, metabolites involved in sugar sensing such as trehalose 6-phosphate were increased. This suggests that TB1 induces bud suppression through the production of inhibitory phytohormones and by reducing sugar levels and energy balance. Interestingly, TB1 also putatively targets several other domestication loci, including teosinte glume architecture1, prol1.1/grassy tillers1, as well as itself. This places tb1 on top of the domestication hierarchy, demonstrating its critical importance during the domestication of maize from teosinte.
许多驯化的作物经过培育以增加顶端优势，与野生祖先相比，其侧枝分枝大大减少。在玉米中，这是通过选择 TEOSINTE BRANCHED1（tb1）TCP 转录因子的功能获得等位基因来实现的。具有显性 Tb1 等位基因如何增加顶端优势的机制尚不清楚。通过 ChIP seq、1mm 腋芽组织的 RNA seq、激素和糖测量，我们确定了 TB1 可能调节的遗传途径。这些途径包括调节赤霉素、脱落酸和茉莉酸等植物激素的途径，但令人惊讶的是，不包括生长素。此外，还增加了参与糖感测的代谢物，如海藻糖 6-磷酸。这表明 TB1 通过产生抑制性植物激素以及降低糖水平和能量平衡来诱导芽抑制。有趣的是，TB1 还可能靶向其他几个驯化基因座，包括 teosinte glume architecture1、prol1.1/grassy tillers1 以及自身。这表明 tb1 在玉米从 teosinte 驯化过程中处于驯化层次结构的顶端，证明了它的重要性。
