The CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION (ESR)-RELATED (CLE) peptide ligands in connection with their receptors are important players in cell-to-cell communications in plants. Here, we investigated the function of the Populus CLV3/ESR-RELATED 47 (PttCLE47) gene during secondary growth and wood formation in hybrid aspen (Populus tremula × tremuloides) using an RNA interference (RNAi) approach. Expression of PttCLE47 peaks in the vascular cambium. Silencing of the PttCLE47 gene expression affected lateral expansion of stems and decreased apical height growth and leaf size. In particular, PttCLE47 RNAi trees exhibited a narrower secondary xylem zone with less xylem cells/cell file. The reduced radial growth phenotype also correlated with a reduced number of cambial cell layers. In agreement with these results, expression of several cambial regulator genes was downregulated in the stems of the transgenic trees in comparison with controls. Altogether, these results suggest that the PttCLE47 gene is a major positive regulator of cambial activity in hybrid aspen, mainly promoting the production of secondary xylem. Furthermore, in contrast to previously characterized CLE genes expressed in the wood-forming zone, PttCLE47 appears to be active at its site of expression.

中文翻译：

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编码胡杨CLV3 / ESR相关蛋白47（PttCLE47）的肽促进杂种杨木中的冈比亚发育和次生木质部形成。

与受体相关的CLAVATA3（CLV3）/胚胎周边地区（ESR）肽配体是植物细胞间通讯的重要参与者。在这里，我们使用RNA干扰（RNAi）方法研究了杂种杨木（Populus tremula×tremuloides）的次级生长和木材形成过程中，胡杨CLV3 / ESR相关47（PttCLE47）基因的功能。PttCLE47在血管形成层中的表达峰值。PttCLE47基因表达的沉默影响茎的侧向扩展，并降低根尖高度的增长和叶的大小。特别地，PttCLE47 RNAi树表现出较窄的次生木质部区，木质部细胞/细胞档案较少。放射状生长表型的减少也与冈比亚细胞层数目的减少有关。与这些结果一致，与对照相比，转基因树的茎中几种冈比亚调节基因的表达下调。总而言之，这些结果表明，PttCLE47基因是杂种白杨中冈比亚活性的主要正调节剂，主要促进次生木质部的产生。此外，与先前在木材形成区表达的特征性CLE基因相反，PttCLE47似乎在其表达位点具有活性。