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Disrupting the cinnamyl alcohol dehydrogenase 1 gene ( Bd CAD 1 ) leads to altered lignification and improved saccharification in Brachypodium distachyon
Author(s) -
Bouvier d'Yvoire Madeleine,
BouchabkeCoussa Oumaya,
Voorend Wannes,
Antelme Sébastien,
Cézard Laurent,
Legée Frédéric,
Lebris Philippe,
Legay Sylvain,
Whitehead Caragh,
McQueenMason Simon J.,
Gomez Leonardo D.,
Jouanin Lise,
Lapierre Catherine,
Sibout Richard
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12053
Subject(s) - cinnamyl alcohol dehydrogenase , brachypodium distachyon , lignin , mutant , brachypodium , biochemistry , chemistry , monolignol , complementation , population , wild type , biology , gene , organic chemistry , biosynthesis , genome , sociology , demography
Summary Brachypodium distachyon ( B rachypodium) has been proposed as a model for grasses, but there is limited knowledge regarding its lignins and no data on lignin‐related mutants. The cinnamyl alcohol dehydrogenase ( CAD ) genes involved in lignification are promising targets to improve the cellulose‐to‐ethanol conversion process. Down‐regulation of CAD often induces a reddish coloration of lignified tissues. Based on this observation, we screened a chemically induced population of B rachypodium mutants (Bd21–3 background) for red culm coloration. We identified two mutants ( Bd4179 and Bd7591 ), with mutations in the Bd CAD 1 gene. The mature stems of these mutants displayed reduced CAD activity and lower lignin content. Their lignins were enriched in 8– O –4‐ and 4– O –5‐coupled sinapaldehyde units, as well as resistant inter‐unit bonds and free phenolic groups. By contrast, there was no increase in coniferaldehyde end groups. Moreover, the amount of sinapic acid ester‐linked to cell walls was measured for the first time in a lignin‐related CAD grass mutant. Functional complementation of the Bd4179 mutant with the wild‐type Bd CAD 1 allele restored the wild‐type phenotype and lignification. Saccharification assays revealed that Bd4179 and Bd7591 lines were more susceptible to enzymatic hydrolysis than wild‐type plants. Here, we have demonstrated that Bd CAD 1 is involved in lignification of B rachypodium. We have shown that a single nucleotide change in Bd CAD 1 reduces the lignin level and increases the degree of branching of lignins through incorporation of sinapaldehyde. These changes make saccharification of cells walls pre‐treated with alkaline easier without compromising plant growth.