AtIPT3 is a key determinant of nitrate-dependent cytokinin biosynthesis in Arabidopsis
AtIPT3 is a key determinant of nitrate-dependent cytokinin biosynthesis in Arabidopsis
复制标题
DOI：
10.1093/pcp/pch119
复制
发表时间：
2004-08-01
影响因子：
4.9
通讯作者：
Sakakibara, H
中科院分区：
文献类型：
--
作者：
Takei, K;Ueda, N;Sakakibara, H
分析了拟南芥腺苷磷酸-异戊烯基转移酶基因（AtIPT 1、AtIPT 3 ~ AtIPT 8）的空间表达模式以及无机氮源对其调控的影响。在成熟植株中，AtIPT在根、叶、茎、花和角果等组织中差异表达。在表达由AtIPT启动子驱动的绿色荧光蛋白（GFP）基因的转基因幼苗中，AtIPT 1：：GFP主要在根的维管中柱中表达，AtIPT 3：：GFP在韧皮部伴随细胞中表达，AtIPT 5：：GFP在侧根原基和周鞘中表达，AtIPT 7：：GFP在根的维管中柱和韧皮部伴随细胞中表达。在长期处理中，AtIPT 5转录本的积累水平与培养基中NO3-和NH 4+的浓度相关。然而，在氮限制条件下，AtIPT 3的表达迅速诱导的NO3-在幼苗伴随着细胞分裂素的积累，而AtIPT 5的表达几乎没有影响。在AtIPT 3的Ds转座子插入突变体中，AtIPT 3转录物和细胞分裂素的NO3依赖性积累显著减少。这些结果表明，氮的供应差异调节AtIPT 3和AtIPT 5的表达，AtIPT 3是细胞分裂素生物合成的关键决定因素，在响应NO3-的可用性的快速变化。
We analyzed the spatial expression pattern of Arabidopsis thaliana adenosine phosphates-isopentenyltransferase genes (AtIPT1, AtIPT3 to AtIPT8) and the effect of inorganic nitrogen sources on their regulation. In mature plants, the AtIPTs were differentially expressed in various tissues including the roots, leaves, stems, flowers and siliques. In transgenic seedlings expressing a gene for green fluorescent protein (GFP) driven by the AtIPT promoters, AtIPT1::GFP was predominantly expressed in the vascular stele of the roots, AtIPT3::GFP was in the phloem companion cells, AtIPT5::GFP was in the lateral root primordium and pericycle, and AtIPT7::GFP was in both the vascular stele and the phloem companion cells of the roots. In a long-term treatment, the accumulation level of AtIPT5 transcript was correlated with the concentrations of NO3- and NH4+ in the growth medium. However, under nitrogen-limited conditions, AtIPT3 expression was rapidly induced by NO3- in the seedlings accompanying the accumulation of cytokinins, whereas AtIPT5 expression was little affected. The NO3--dependent accumulation of both the AtIPT3 transcript and the cytokinins was markedly reduced in a Ds transposon-insertion mutant of AtIPT3. These results suggest that nitrogen availability differentially regulates expression of AtIPT3 and AtIPT5, and that AtIPT3 is a key determinant of cytokinin biosynthesis in response to rapid changes in the availability of NO3-.