BACKGROUND The steroidal hormones brassinosteroids (BRs) play important roles in plant growth and development. The pathway and genes involved in BR biosynthesis have been identified primarily in model plants like Arabidopsis, but little is known about BR biosynthesis in woody fruits such as pear. RESULTS In this study, we found that applying exogenous brassinolide (BL) could significantly increase the stem growth and rooting ability of Pyrus ussuriensis. PcDWF1, which had a significantly lower level of expression in the dwarf-type pear than in the standard-type pear, was cloned for further analysis. A phylogenetic analysis showed that PcDWF1 was a pear brassinosteroid biosynthetic gene that was homologous to AtDWARF1. The subcellular localization analysis indicated that PcDWF1 was located in the plasma membrane. Overexpression of PcDWF1 in tobacco (Nicotiana tabacum) or pear (Pyrus ussuriensis) plants promoted the growth of the stems, which was caused by a larger cell size and more developed xylem than those in the control plants, and the rooting ability was significantly enhanced. In addition to the change in vegetative growth, the tobacco plants overexpressing PcDWF1 also had a delayed flowering time and larger seed size than did the control tobacco plants. These phenotypes were considered to result from the higher BL contents in the transgenic lines than in the control tobacco and pear plants. CONCLUSIONS Taken together, these results reveal that the pear BR biosynthetic gene PcDWF1 affected the vegetative and reproductive growth of Pyrus ussuriensis and Nicotiana tabacum and could be characterized as an important BR biosynthetic gene in perennial woody fruit plants.

中文翻译：

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PcDWF1是梨油菜素类固醇生物合成基因，与AtDWARF1同源，影响植物的营养和生殖生长。


背景技术甾体激素油菜素内酯(BR)在植物生长和发育中发挥重要作用。 BR生物合成所涉及的途径和基因主要在拟南芥等模式植物中被鉴定，但对梨等木本水果中的BR生物合成知之甚少。结果在本研究中，我们发现施用外源油菜素内酯（BL）可以显着提高乌苏里梨的茎生长和生根能力。 PcDWF1在矮化型梨中的表达水平显着低于标准型梨，被克隆用于进一步分析。系统发育分析表明，PcDWF1是梨油菜素类固醇生物合成基因，与AtDWARF1同源。亚细胞定位分析表明PcDWF1位于质膜上。 PcDWF1在烟草（Nicotiana tabacum）或梨（Pyrus ussuriensis）植物中的过表达促进了茎的生长，这是由于比对照植物具有更大的细胞尺寸和更发达的木质部所致，并且生根能力显着增强。除了营养生长的变化之外，过表达 PcDWF1 的烟草植物还比对照烟草植物具有延迟的开花时间和更大的种子尺寸。这些表型被认为是由于转基因品系中的 BL 含量高于对照烟草和梨植物的结果。结论 综上所述，这些结果表明，梨 BR 生物合成基因 PcDWF1 影响梨和烟草的营养和生殖生长，可能是多年生木本果类植物中重要的 BR 生物合成基因。