Genetic and molecular basis of grass cell wall biosynthesis and degradability. II. Lessons from brown-midrib mutants.
The brown-midrib mutants of maize have a reddish-brown pigmentation of the leaf midrib and stalk pith, associated with lignified tissues. These mutants progressively became models for lignification genetics and biochemical studies in maize and grasses. Comparisons at silage maturity of bm1, bm2, bm3, bm4 plants highlighted their reduced lignin, but also illustrated the biochemical specificities of each mutant in p-coumarate, ferulate ester and etherified ferulate content, or syringyl/guaiacyl monomer ratio after thioacidolysis. Based on the current knowledge of the lignin pathway, and based on presently developed data and discussions, C3H and CCoAOMT activities are probably major hubs in controlling cell-wall lignification (and digestibility). It is also likely that ferulates arise via the CCoAOMT pathway.
Barrière
Yves
Y
Unité dé génétique et d'amélioration des plantes fourragères, INRA, 86600 Lusignan, France. barriere@lusignan.inra.fr
Ralph
John
J
Méchin
Valérie
V
Guillaumie
Sabine
S
Grabber
John H
JH
Argillier
Odile
O
Chabbert
Brigitte
B
Lapierre
Catherine
C
D002473:Cell Wall / Q000378:metabolism*; D003373:Coumaric Acids / Q000378:metabolism; D014644:Genetic Variation; D008031:Lignin / Q000737:chemistry / Q000378:metabolism; D008780:Methyltransferases / Q000235:genetics; D009154:Mutation; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure
D003373:Coumaric Acids; D008031:Lignin; C004999:ferulic acid; D008780:Methyltransferases