Cambium reactivation independent of bud unfolding involves de novo IAA biosynthesis in cambium regions in Populus tomentosa Carr.
Cambium reactivation independent of bud unfolding involves de novo IAA biosynthesis in cambium regions in Populus tomentosa Carr.
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DOI：
10.1007/s11738-013-1220-2
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发表时间：
2013-01
影响因子：
2.6
通讯作者：
Wanxuan Li;Q. Ding;K. Cui;Xin He
中科院分区：
文献类型：
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作者：
Wanxuan Li;Q. Ding;K. Cui;Xin He
温带树木春季形成层的恢复对适应和生长具有重要意义。在一些树木中，形成层细胞分裂的恢复发生在花蕾形成之前。然而，关于在这些树的再激活过程中促进形成层细胞分裂的内部刺激来源的知识是有限的。本文研究了毛白杨在自然和水培养条件下，形成层在恢复过程中随营养芽的展开而发生的解剖学变化。同时，测定了形成层活化过程中游离吲哚-3-乙酸（IAA）的含量及其产生相关酶的转录本。结果表明，毛毛假丝茅在形成层活化过程中，形成层细胞分裂发生在芽展开之前。有趣的是，在芽展开前，IAA水平和参与IAA新生生物合成的醛氧化酶2和腈酶2编码酶的同源物转录本会增加，而IAA偶联水解酶的转录本会几乎没有增加。这些结果表明，形成层区域新生生物合成的游离IAA促进了芽展开前形成层的再激活，为形成层再激活的调控机制提供了新的认识。
Cambium reactivation of temperate trees in spring is important for adaptation and growth. In some trees, the resumption of cambium cell division occurs before bud flush. However, knowledge about the source of the internal stimuli that promote cambium cell division during reactivation in these trees is limited. Here, the anatomical changes of cambium during reactivation along with the unfolding of vegetative buds in Populus tomentosa were examined under natural and water-culture conditions. Meanwhile, the levels of free indole-3-acetic acid (IAA) and transcripts of enzymes involved in its production were measured during cambium reactivation. The results showed that cambium cell division occurred before bud unfolding during cambium reactivation in P. tomentosa. Interestingly, the levels of IAA and the transcripts of poplar homologs of aldehyde oxidase 2 and nitrilases 2 encoding enzymes functioning in de novo IAA biosynthesis increased before bud unfolding, while the transcript levels of IAA conjugate hydrolases almost showed no increase. These results suggest that free IAA from de novo biosynthesis in cambium regions promotes cambium reactivation before bud unfolding, providing new insights into the regulatory mechanism of cambium reactivation.