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CAD 1 and CCR 2 protein complex formation in monolignol biosynthesis in Populus trichocarpa
Author(s) -
Yan Xiaojing,
Liu Jie,
Kim Hoon,
Liu Baoguang,
Huang Xiong,
Yang Zhichang,
Lin YingChung Jimmy,
Chen Hao,
Yang Chenmin,
Wang Jack P.,
Muddiman David C.,
Ralph John,
Sederoff Ronald R.,
Li Quanzi,
Chiang Vincent L.
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15505
Subject(s) - populus trichocarpa , monolignol , biosynthesis , chemistry , biochemistry , biology , botany , microbiology and biotechnology , gene , genome
Summary Lignin is the major phenolic polymer in plant secondary cell walls and is polymerized from monomeric subunits, the monolignols. Eleven enzyme families are implicated in monolignol biosynthesis. Here, we studied the functions of members of the cinnamyl alcohol dehydrogenase ( CAD ) and cinnamoyl‐CoA reductase ( CCR ) families in wood formation in Populus trichocarpa , including the regulatory effects of their transcripts and protein activities on monolignol biosynthesis. Enzyme activity assays from stem‐differentiating xylem ( SDX ) proteins showed that RNA i suppression of Ptr CAD 1 in P. trichocarpa transgenics caused a reduction in SDX CCR activity. RNA i suppression of Ptr CCR 2 , the only CCR member highly expressed in SDX , caused a reciprocal reduction in SDX protein CAD activities. The enzyme assays of mixed and coexpressed recombinant proteins supported physical interactions between Ptr CAD 1 and Ptr CCR 2. Biomolecular fluorescence complementation and pull‐down/co‐immunoprecipitation experiments supported a hypothesis of Ptr CAD 1/Ptr CCR 2 heterodimer formation. These results provide evidence for the formation of Ptr CAD 1/Ptr CCR 2 protein complexes in monolignol biosynthesis in planta .