Abstract Retardation of plant growth is important in horticultural plant production and is generally achieved through the application of various chemical plant growth regulators (PGRs). Chrysanthemum plants grown in pots (pot-mums), are typically treated with PGRs to produce a compact form; however, these compounds can be hazardous to the environment and human health. In an effort to develop a method to produce compact chrysanthemum plants without using PGRs, we introduced the BrSRS7 gene from Brassica rapa L. ssp. pekinensis into chrysanthemum with its expression controlled by the promoter of the chrysanthemum actin gene (CmActin). As a first step, we evaluated the regeneration capacities of seven pot-mum cultivars and identified the Peace Copper (PC) cultivar as having the best regeneration efficiency. After transformation of the BrSRS7 gene into PC followed by selection and 5 rounds of vegetative subcultivation, 11 transgenic lines were identified for analysis. Internode lengths were reduced in all lines compared to control plants, but plant heights of some lines were similar to those of control plants. Four transgenic lines were selected for a sixth round of subcultivation and for further study. We determined the relative expression levels of gibberellin- and auxin-related genes in the four transgenic lines. Of the auxin-related genes, ARF2 and YUCCA10 showed higher expression in the transgenic lines than in the control. The expression levels of GA-related genes decreased overall in P-33, which showed the greatest decrease in height. Subjecting the transgenic lines to a dwarfing treatment with the PGR B9 showed that the plants could be reduced to actual marketable size with only a single dwarfing treatment. Our results demonstrate the possibility of using the BrSRS7 gene to produce compact chrysanthemum plants with reduced or no use of PGRs.

中文翻译：

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盆栽菊[Chrysanthemum morifolium Ramat]中芸苔SRS7基因的过表达降低株高

摘要 植物生长迟缓在园艺植物生产中很重要，通常通过应用各种化学植物生长调节剂 (PGRs) 来实现。盆栽菊花植物（pot-mums）通常用 PGR 处理以产生紧凑的形式；然而，这些化合物可能对环境和人类健康有害。为了开发一种不使用 PGR 生产紧凑型菊花植物的方法，我们从芸苔属植物中引入了 BrSRS7 基因。pekinensis 进入菊花，其表达受菊花肌动蛋白基因 (CmActin) 的启动子控制。作为第一步，我们评估了七个盆栽品种的再生能力，并确定了Peace Copper (PC) 品种的再生效率最高。在将 BrSRS7 基因转化到 PC 中，然后进行选择和 5 轮营养传代后，鉴定了 11 个转基因品系用于分析。与对照植物相比，所有品系的节间长度均减少，但一些品系的植物高度与对照植物的相似。选择了四个转基因品系用于第六轮传代和进一步研究。我们确定了四个转基因品系中赤霉素和生长素相关基因的相对表达水平。在生长素相关基因中，ARF2 和 YUCCA10 在转基因株系中的表达高于对照。GA 相关基因的表达水平在 P-33 中总体下降，其中高度下降幅度最大。用 PGR B9 对转基因品系进行矮化处理表明，仅通过一次矮化处理就可以将植物缩小到实际可销售的大小。我们的结果证明了使用 BrSRS7 基因生产具有减少或不使用 PGR 的紧凑菊花植物的可能性。