González-Grandío Eduardo, Pajoro Alice, Franco-Zorrilla José M, Tarancón Carlos, Immink Richard G H, Cubas Pilar
Department of Plant Molecular Genetics, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Bioscience, Wageningen Plant Research, Wageningen University and Research, 6708 PB Wageningen, The Netherlands.
Proc Natl Acad Sci U S A. 2017 Jan 10;114(2):E245-E254. doi: 10.1073/pnas.1613199114. Epub 2016 Dec 27.
Shoot-branching patterns determine key aspects of plant life and are important targets for crop breeding. However, we are still largely ignorant of the genetic networks controlling locally the most important decision during branch development: whether the axillary bud, or branch primordium, grows out to give a lateral shoot or remains dormant. Here we show that, inside the buds, the TEOSINTE BRANCHED1, CYCLOIDEA, PCF (TCP) transcription factor BRANCHED1 (BRC1) binds to and positively regulates the transcription of three related Homeodomain leucine zipper protein (HD-ZIP)-encoding genes: HOMEOBOX PROTEIN 21 (HB21), HOMEOBOX PROTEIN 40 (HB40), and HOMEOBOX PROTEIN 53 (HB53). These three genes, together with BRC1, enhance 9-CIS-EPOXICAROTENOID DIOXIGENASE 3 (NCED3) expression, lead to abscisic acid accumulation, and trigger hormone response, thus causing suppression of bud development. This TCP/HD-ZIP genetic module seems to be conserved in dicot and monocotyledonous species to prevent branching under light-limiting conditions.
茎分枝模式决定了植物生命的关键方面，是作物育种的重要目标。然而，我们在很大程度上仍不清楚在分枝发育过程中局部控制最重要决定的遗传网络：腋芽或分枝原基是生长形成侧枝还是保持休眠。在这里，我们表明，在芽内部，玉米分枝1、类细胞周期蛋白、PCF（TCP）转录因子BRANCHED1（BRC1）与三个相关的编码同源异型域亮氨酸拉链蛋白（HD-ZIP）的基因结合，并正向调节它们的转录：同源异型盒蛋白21（HB21）、同源异型盒蛋白40（HB40）和同源异型盒蛋白53（HB53）。这三个基因与BRC1一起增强9-顺式环氧类胡萝卜素双加氧酶3（NCED3）的表达，导致脱落酸积累，并触发激素反应，从而抑制芽的发育。这种TCP/HD-ZIP遗传模块似乎在双子叶和单子叶植物物种中是保守的，以防止在光照受限条件下的分枝。
