{"title":"A COBRA family protein, PtrCOB3, contributes to gelatinous layer formation of tension wood fibers in poplar.","authors":"Wenjing Xu, Hao Cheng, Jiyao Cheng, Siran Zhu, Yongyao Cui, Chong Wang, Jianzhen Wu, Xingguo Lan, Yuxiang Cheng","doi":"10.1093/plphys/kiae328","DOIUrl":null,"url":null,"abstract":"<p><p>Angiosperm trees usually develop tension wood (TW) in response to gravitational stimulation. TW comprises abundant gelatinous (G-) fibers with thick G-layers primarily composed of crystalline cellulose. Understanding the pivotal factors governing G-layer formation in TW fiber remains elusive. This study elucidates the role of a Populus trichocarpa COBRA family protein, PtrCOB3, in the G-layer formation of TW fibers. PtrCOB3 expression was upregulated, and its promoter activity was enhanced during TW formation. Comparative analysis with wild-type trees revealed that ptrcob3 mutants, mediated by Cas9/gRNA gene editing, were incapable of producing G-layers within TW fibers and showed severely impaired stem lift. Fluorescence immunolabeling data revealed a dearth of crystalline cellulose in the tertiary cell wall (TCW) of ptrcob3 TW fibers. The role of PtrCOB3 in G-layer formation is contingent upon its native promoter, as evidenced by the comparative phenotypic assessments of pCOB11::PtrCOB3, pCOB3::PtrCOB3, and pCOB3::PtrCOB11 transgenic lines in the ptrcob3 background. Overexpression of PtrCOB3 under the control of its native promoter expedited G-layer formation within TW fibers. We further identified 3 transcription factors that bind to the PtrCOB3 promoter and positively regulate its transcriptional levels. Alongside the primary TCW synthesis genes, these findings enable the construction of a 2-layer transcriptional regulatory network for the G-layer formation of TW fibers. Overall, this study uncovers mechanistic insight into TW formation, whereby a specific COB protein executes the deposition of cellulose, and consequently, G-layer formation within TW fibers.</p>","PeriodicalId":20101,"journal":{"name":"Plant Physiology","volume":null,"pages":null},"PeriodicalIF":6.5000,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Plant Physiology","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1093/plphys/kiae328","RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PLANT SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Angiosperm trees usually develop tension wood (TW) in response to gravitational stimulation. TW comprises abundant gelatinous (G-) fibers with thick G-layers primarily composed of crystalline cellulose. Understanding the pivotal factors governing G-layer formation in TW fiber remains elusive. This study elucidates the role of a Populus trichocarpa COBRA family protein, PtrCOB3, in the G-layer formation of TW fibers. PtrCOB3 expression was upregulated, and its promoter activity was enhanced during TW formation. Comparative analysis with wild-type trees revealed that ptrcob3 mutants, mediated by Cas9/gRNA gene editing, were incapable of producing G-layers within TW fibers and showed severely impaired stem lift. Fluorescence immunolabeling data revealed a dearth of crystalline cellulose in the tertiary cell wall (TCW) of ptrcob3 TW fibers. The role of PtrCOB3 in G-layer formation is contingent upon its native promoter, as evidenced by the comparative phenotypic assessments of pCOB11::PtrCOB3, pCOB3::PtrCOB3, and pCOB3::PtrCOB11 transgenic lines in the ptrcob3 background. Overexpression of PtrCOB3 under the control of its native promoter expedited G-layer formation within TW fibers. We further identified 3 transcription factors that bind to the PtrCOB3 promoter and positively regulate its transcriptional levels. Alongside the primary TCW synthesis genes, these findings enable the construction of a 2-layer transcriptional regulatory network for the G-layer formation of TW fibers. Overall, this study uncovers mechanistic insight into TW formation, whereby a specific COB protein executes the deposition of cellulose, and consequently, G-layer formation within TW fibers.
期刊介绍:
Plant Physiology® is a distinguished and highly respected journal with a rich history dating back to its establishment in 1926. It stands as a leading international publication in the field of plant biology, covering a comprehensive range of topics from the molecular and structural aspects of plant life to systems biology and ecophysiology. Recognized as the most highly cited journal in plant sciences, Plant Physiology® is a testament to its commitment to excellence and the dissemination of groundbreaking research.
As the official publication of the American Society of Plant Biologists, Plant Physiology® upholds rigorous peer-review standards, ensuring that the scientific community receives the highest quality research. The journal releases 12 issues annually, providing a steady stream of new findings and insights to its readership.