Open AccessDwarfism of high‐monolignol Arabidopsis plants is rescued by ectopic LACCASE overexpression
Author(s) -
Perkins Mendel L.,
Schuetz Mathias,
Unda Faride,
Smith Rebecca A.,
Sibout Richard,
Hoffmann Natalie J.,
Wong Darren C. J.,
Castellarin Simone D.,
Mansfield Shawn D.,
Samuels Lacey
Publication year - 2020
Publication title -
plant direct
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.211
H-Index - 11
ISSN - 2475-4455
DOI - 10.1002/pld3.265
Subject(s) - monolignol , ectopic expression , arabidopsis , wild type , mutant , biology , dwarfism , lignin , phenylpropanoid , myb , xylem , glucoside , botany , plant physiology , biochemistry , transcription factor , gene , biosynthesis , medicine , alternative medicine , pathology
Lignin is a key secondary cell wall chemical constituent, and is both a barrier to biomass utilization and a potential source of bioproducts. The Arabidopsis transcription factors MYB58 and MYB63 have been shown to upregulate gene expression of the general phenylpropanoid and monolignol biosynthetic pathways. The overexpression of these genes also results in dwarfism. The vascular integrity, soluble phenolic profiles, cell wall lignin, and transcriptomes associated with these MYB‐overexpressing lines were characterized. Plants with high expression of MYB58 and MYB63 had increased ectopic lignin and the xylem vessels were regular and open, suggesting that the stunted growth is not associated with loss of vascular conductivity. MYB58 and MYB63 overexpression lines had characteristic soluble phenolic profiles with large amounts of monolignol glucosides and sinapoyl esters, but decreased flavonoids. Because loss of function lac4 lac17 mutants also accumulate monolignol glucosides, we hypothesized that LACCASE overexpression might decrease monolignol glucoside levels in the MYB‐overexpressing plant lines. When laccases related to lignification ( LAC4 or LAC17 ) were co‐overexpressed with MYB63 or MYB58 , the dwarf phenotype was rescued. Moreover, the overexpression of either LAC4 or LAC17 led to wild‐type monolignol glucoside levels, as well as wild‐type lignin levels in the rescued plants. Transcriptomes of the rescued double MYB63‐OX/LAC17‐OX overexpression lines showed elevated, but attenuated, expression of the MYB63 gene itself and the direct transcriptional targets of MYB63. Contrasting the dwarfism from overabundant monolignol production with dwarfism from lignin mutants provides insight into some of the proposed mechanisms of lignin modification‐induced dwarfism.