We used primers designed on conserved gene regions of several species to isolate the most expressed genes of the lignin pathway in four
Saccharum
species.
S. officinarum
and
S. barberi
have more sucrose in the culms than
S. spontaneum
and
S. robustum
, but less polysaccharides and lignin in the cell wall.
S. spontaneum
, and
S. robustum
had the lowest S/G ratio and a lower rate of saccharification in mature internodes. Surprisingly, except for CAD, 4CL, and CCoAOMT for which we found three, two, and two genes, respectively, only one gene was found for the other enzymes and their sequences were highly similar among the species.
S. spontaneum
had the highest expression for most genes.
CCR
and
CCoAOMT B
presented the highest expression;
4CL
and
F5H
showed increased expression in mature tissues;
C3H
and
CCR
had higher expression in
S. spontaneum
, and one of the CADs isolated (
CAD
B) had higher expression in
S
.
officinarum
. The similarity among the most expressed genes isolated from these species was unexpected and indicated that lignin biosynthesis is conserved in
Saccharum
including commercial varieties Thus the lignin biosynthesis control in sugarcane may be only fully understood with the knowledge of the promotor region of each gene.