The IPT gene encodes isopentenyl pyrophosphate transferase, a key enzyme in cytokinin biosynthesis. We introduced IPT under the control of the CaMV35S promoter into Asakura-sanshoo (Zanthoxylum piperitum (L.) DC. f. inerme Makino) via stable Agrobacterium tumefaciens-mediated transformation. Three of 3-year-old transgenic Asakura-sanshoo lines Y5, Y16, and Y17 were used to evaluate the effects of IPT expression on the morphological characteristics, leaf senescence, and essential oil composition. Introduced IPT into Asakura-sanshoo stimulated an increase in cytokinin content and a decrease in auxin level. The increase in the cytokinin/auxin ratio affected the tree architecture in 3-year-old transgenic lines. The phenotypes of transgenic lines included reduced stem elongation, decreased leaf surface area, increased branching, and delayed leaf senescence. The expression of IPT in Asakura-sanshoo also affected the leaf essential oil composition. The amount of oxygenated sesquiterpenoid compounds in Y5 and Y16 was 21.1 and 15.8 % higher, respectively, than that in wild type (WT). The amount of aromatic compounds in Y5 and Y16 was 2.9 and 24.6 % lower, respectively, than that in WT. These results show that ipt expression in Asakura-sanshoo conferred desirable traits, including a dwarf growth habit, delayed senescence, and increased concentrations of some sesquiterpenoid compounds.

中文翻译：

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IPT 在 Asakura-sanshoo (Zanthoxylum piperitum (L.) DC. f. inerme Makino) 中的表达改变树结构、延迟叶子衰老并改变叶子精油成分

IPT 基因编码异戊烯焦磷酸转移酶，这是细胞分裂素生物合成的关键酶。我们通过稳定的根癌农杆菌介导的转化将在 CaMV35S 启动子控制下的 IPT 引入 Asakura-sanshoo (Zanthoxylum piperitum (L.) DC. f. inerme Makino)。使用三个 3 年生的转基因 Asakura-sanshoo 品系 Y5、Y16 和 Y17 来评估 IPT 表达对形态特征、叶片衰老和精油成分的影响。在 Asakura-sanshoo 中引入 IPT 刺激了细胞分裂素含量的增加和生长素水平的降低。细胞分裂素/生长素比率的增加影响了 3 年生转基因株系的树结构。转基因品系的表型包括茎伸长减少、叶表面积减少、分枝增加、和延缓叶片衰老。IPT 在 Asakura-sanshoo 中的表达也影响了叶精油的组成。Y5 和 Y16 中含氧倍半萜类化合物的量分别比野生型 (WT) 高 21.1% 和 15.8%。Y5 和 Y16 中芳族化合物的含量分别比 WT 中的低 2.9% 和 24.6%。这些结果表明 Asakura-sanshoo 中的 ipt 表达赋予了理想的特征，包括矮小的生长习性、延缓衰老和增加一些倍半萜类化合物的浓度。分别比 WT 低 6%。这些结果表明 Asakura-sanshoo 中的 ipt 表达赋予了理想的特征，包括矮小的生长习性、延缓衰老和增加一些倍半萜类化合物的浓度。分别比 WT 低 6%。这些结果表明 Asakura-sanshoo 中的 ipt 表达赋予了理想的特征，包括矮小的生长习性、延缓衰老和增加一些倍半萜类化合物的浓度。