Biology Reference
In-Depth Information
Fig. 1. Expression tree compared to phylogenetic tree for Arabidopsis thaliana
laccases family. (A) Expression tree for arabidopsis laccases, the scale bar represents
the degree of coexpression between any two genes; genes highly coexpressed have a
distance close to zero (
http://genecat.mpg.de
)
. (B) Phylogenetic tree for arabidopsis
laccases using protein alignment, the scale bar represents 0.05 substitutions per
position (
http://www.ebi.ac.uk/clustalw/
)
.
laccases (AtLAC2, AtLAC4, AtLAC10, AtLAC11, AtLAC16,andAtLAC17),
which are all expressed in stems with the exception of AtLAC16,whichdoes
not present any organ specificity. The high conservation of the genes encoding
for the stem-specific laccases supports the hypothesis that they could have
redundant functions and could be potentially involved in lignification.
Up to now, knockout or knockdown T-DNA mutants have been identified
for each of these 17 laccases (
Table II
), with the exception of AtLAC1.
Different phenotypes were assigned to lac2, lac4, lac8, lac15 (tt10), and lac17
(
Berthet et al., 2011; Brown et al.,2005;Caiet al.,2006;Pourcelet al.,2005
),
which suggests different functions for these laccases. The AtLAC15 deficient
line presents a seed-associated phenotype whereas mutants for AtLAC4 and
AtLAC17 show some alterations in stem phenotype (
Berthet et al.,2011
). The
relationship between the stem- or seed-localized phenotype and the expression
profile of the corresponding mutated laccases led to the first functional char-
acterization of arabidopsis laccases genes, as discussed below. Currently, no
information is available about the function of root-specific laccases.
In Populus trichocarpa, 51 putative laccase-encoding genes were identified
from the available functional annotation of the poplar genome in Phytozome
database
http://www.phytozome.net
(
Goodstein et al., 2011
). The compara-
tive analyses between poplar and arabidopsis of protein similarity, gene
expression and miRNA target prediction can help us to better delineate the
