Strong decrease in lignin content without significant alteration of plant development is induced by simultaneous down‐regulation of cinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) in tobacco plants

Abstract

Different transgenic tobacco lines down-regulated for either one or two enzymes of the monolignol pathway were compared for their lignin content and composition, and developmental patterns. The comparison concerned CCR and CAD down-regulated lines (homozygous or heterozygous for the transgene) and the hybrids resulting from the crossing of transgenic lines individually altered for CCR or CAD activities. Surprisingly, the crosses containing only one allele of each antisense transgene, exhibit a dramatic reduction of lignin content similar to the CCR down-regulated parent but, in contrast to this transgenic line, display a normal phenotype and only slight alterations of the shape of the vessels. Qualitatively the lignin of the double transformant displays characteristics more like the wild type control than either of the other transgenics. In the transgenics with a low lignin content, the transformations induced other biochemical changes involving polysaccharides, phenolic components of the cell wall and also soluble phenolics. These results show that the ectopic expression of a specific transgene may have a different impact depending on the genetic background and suggest that the two transgenes present in the crosses may operate synergistically to reduce the lignin content. In addition, these data confirm that plants with a severe reduction in lignin content may undergo normal development at least in controlled conditions.

Functional and Structural Characterization of a Cation-dependent O-Methyltransferase from the Cyanobacterium Synechocystis sp. Strain PCC 6803

“…Tremendous efforts have been undertaken to manipulate the composition of lignin in various plant species with the focus on methylating enzymes (7,39,40) or those involved in earlier biosynthetic steps, e.g. cinnamyl alcohol dehydrogenase and cinnamoyl-CoA reductase (41). Expression of enzymes targeting para-hydroxy groups in the appropriate gymnosperm or angiosperm background may allow for the production of novel types of lignin with altered properties such as changes in the degree or mode of polymerization that might effect digestibility by ruminants (42).…”

Cinnamoyl-CoA reductase, a key enzyme in lignin biosynthesis, is an effector of small GTPase Rac in defense signaling in rice

“…One gram (fresh weight) of rice suspension cells was ground in liquid nitrogen, and total proteins were extracted in 0.1 M Tris⅐HCl, pH 7.5͞2% polyethylene glycol 6000 (wt͞vol)͞5 mM DTT͞2% polyvinylpolypyrrolidone (wt͞vol) (31). The crude extracts were clarified by centrifugation at 16,000 ϫ g for 10 min at 4°C.…”

FLEXIBLE CULM 1 encoding a cinnamyl-alcohol dehydrogenase controls culm mechanical strength in rice

“…The resistance of xylem to compressive stresses imposed by water transport and the mass of the plants is important to plant's growth and development. In addition, the insolubility and complexity of the lignin polymer makes it resistant to degradation by most microorganisms (Brill et al 1999;Chabannes et al 2001;Jones et al 2001).…”