ABSTRACT Environmental factors such as photoperiod, temperature, phytohormones, sugars, and soil nutrients can affect the development of axillary meristems and emergence of shoot branches in plants. We investigated how an extended period of cold exposure to Arabidopsis plants before and after inflorescence meristem differentiation would affect plant growth and shoot branching. The number of rosette leaves and shoot branches increased when wild type (WT) juvenile seedlings, but not adult plants, were subjected to a prolonged cold exposure (10/7°C day/night cycle). As the duration of cold exposure to WT juvenile seedlings increased, so too did the rosette area, number of leaves, and rosette branches revealing an extended period of vegetative growth. The prolonged cold treatment also increased the primary inflorescence stem height and number of cauline branches in WT plants revealing a delay in reproductive development that could be altered by early (set domain group 8; sdg8) and late (methyltransferase 1; met1) flowering mutants. The axillary buds/leaf and rosette branches/leaf ratios declined significantly in WT, yet were enhanced in the loss-of-function of carotenoid cleavage dioxygenase 7 (ccd7) and teosinte branched 1 (brc1) hyper-branched mutants. This indicated that axillary meristem differentiation continued during the cold exposure, which did not directly impact axillary bud formation or shoot branching. We conclude that a prolonged cold exposure to juvenile seedlings prior to inflorescence meristem development extended vegetative growth and delayed the reproductive phase to allow additional leaf primordia and axillary meristems to differentiate that enhanced the number of shoot branches in Arabidopsis.

中文翻译：

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拟南芥幼苗长期低温暴露可延长营养生长并增加枝条数量

摘要 光周期、温度、植物激素、糖分和土壤养分等环境因素会影响植物腋生分生组织的发育和枝条的出现。我们研究了在花序分生组织分化之前和之后对拟南芥植物的长时间冷暴露如何影响植物生长和枝条分枝。当野生型 (WT) 幼苗而非成年植株长时间暴露在低温环境中（10/7°C 昼/夜循环）时，莲座丛叶和枝条的数量会增加。随着冷暴露于 WT 幼苗的持续时间增加，莲座面积、叶片数量和莲座丛枝条也显示出营养生长的延长期。延长的冷处理还增加了 WT 植物的初级花序茎高度和茎生分枝的数量，表明生殖发育的延迟可能会被早期（设置域组 8；sdg8）和晚期（甲基转移酶 1；met1）开花突变体改变。WT 中腋芽/叶和莲座丛枝/叶比率显着下降，但类胡萝卜素裂解双加氧酶 7 (ccd7) 和 teosinte 分支 1 (brc1) 超分支突变体的功能丧失有所增强。这表明在冷暴露期间腋生分生组织继续分化，不直接影响腋芽形成或枝条分枝。