Gibberellins (GA) are important hormones in the regulation of plant growth and development, especially plant dwarfism. In the present study, the leaf length and active gibberellin content of a dwarf mutant were lower than that of Kentucky bluegrass (Poa pratensis L.) wild type, and the plant height of the dwarf mutant increased following the application of GA₃. To gain insights into the GA metabolism pathway in turfgrass and the role of GA-related genes in the dwarf phenotype, five GA-related genes in P. pratensis, namely PpKS, PpKO, PpGA20ox1, PpGA3ox1, and PpGA2ox5, were isolated and identified. According to expression analysis, the expression levels of PpKS were lower in the dwarf mutant than in the wild type, whereas the transcript abundances of PpGA20ox1 and PpGA2ox5 were raised in dwarf mutant. Further evaluation of the expression profiles of these genes in response to GA₃ showed that the studied genes were differentially regulated after exogenous treatment. Furthermore, it was found that PpGA2ox5-overexpressing transgenic lines produced the phenotypes of dwarfism and dark green blades, whereas PpGA20ox1 overexpression in Arabidopsis had the opposite effect. Through the result of the diverse expression patterns of GA genes and functional study of PpGA2ox5 and PpGA20ox1, it is indicated that the genes involved in the metabolism of GA are important for regulating plant height and speculated that PpGA2ox5 could be the breeding target that used to cultivate dwarf varieties of Kentucky bluegrass.

中文翻译：

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赤霉素相关基因在早熟禾野生型和矮化突变体中的差异表达暗示其在调节株高中的作用

赤霉素（GA）是调节植物生长发育特别是植物矮化的重要激素。在本研究中，矮化突变体的叶长和活性赤霉素含量低于肯塔基早熟禾（Poa pratensis L.）野生型，并且矮化突变体的株高随着施用GA _{3 的}增加而增加。为了深入了解草坪草中 GA 代谢途径以及 GA 相关基因在矮化表型中的作用，P. pratensis 中的5 个 GA 相关基因，即PpKS、PpKO、PpGA20ox1、PpGA3ox1和PpGA2ox5，被隔离和鉴定。根据表达分析，矮突变体中PpKS的表达水平低于野生型，而矮突变体中PpGA20ox1和PpGA2ox5的转录丰度升高。对这些基因响应 GA ₃的表达谱的进一步评估表明，所研究的基因在外源处理后受到差异调节。此外，发现PpGA2ox5 过表达的转基因品系产生了侏儒症和深绿色叶片的表型，而PpGA20ox1在拟南芥中过表达产生了相反的效果。通过GA基因的不同表达模式和PpGA2ox5和PpGA20ox1的功能研究，表明参与GA代谢的基因对调节株高具有重要意义，推测PpGA2ox5可能是用于栽培的育种靶点。肯塔基兰草的矮化品种。