PtaRHE1, a Populus tremula × Populus alba RING‐H2 protein of the ATL family, has a regulatory role in secondary phloem fibre development

• DOI: 10.1111/tpj.12867
• Publication Date: 2015-04-25T11:45:24Z
• Authors: Fabien Baldacci‐C...; Jihad Moussawi; Jean‐Charles Leplé; Rebecca Van Acker; Annegret Kohler; Julie Candiracci; Laure Twyffels; Antanas V. Spokev...; Gerd Bossinger; Françoise Laurans; Nicole Brunel; Marjorie Vermeersch; Wout Boerjan; Mondher El Jaziri; Marie Baucher
• Keywords: 580; 0301 basic medicine; 570; PtaRHE1; Plant Stems; Populus tremula × Populus alba; Chimera; phloem fibre development; Molecular Sequence Data; Sciences bio-médicales et agricoles; Phloem; Plants, Genetically Modified; Populus tremula × Populus alba; RING-H2; vascular tissues; 03 medical and health sciences; Phenotype; Populus; Cell Wall; Gene Expression Regulation, Plant; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; Plant Proteins

SummaryREALLY INTERESTING NEW GENE (RING) proteins play important roles in the regulation of many processes by recognizing target proteins for ubiquitination. Previously, we have shown that the expression of PtaRHE1, encoding a Populus tremula × Populus alba RING‐H2 protein with E3 ubiquitin ligase activity, is associated with tissues undergoing secondary growth. To further elucidate the role of PtaRHE1 in vascular tissues, we have undertaken a reverse genetic analysis in poplar. Within stem secondary vascular tissues, PtaRHE1 and its corresponding protein are expressed predominantly in the phloem. The downregulation of PtaRHE1 in poplar by artificial miRNA triggers alterations in phloem fibre patterning, characterized by an increased portion of secondary phloem fibres that have a reduced cell wall thickness and a change in lignin composition, with lower levels of syringyl units as compared with wild‐type plants. Following an RNA‐seq analysis, a biological network involving hormone stress signalling, as well as developmental processes, could be delineated. Several candidate genes possibly associated with the altered phloem fibre phenotype observed in amiRPtaRHE1 poplar were identified. Altogether, our data suggest a regulatory role for PtaRHE1 in secondary phloem fibre development.