Kyoto University scientists characterized the lignin of mutant rice
developed using the CRISPR-Cas9 system. The results are published in The
Plant Journal.

In a previous study, Yuri Takeda and colleagues identified a rice gene
encoding coniferaldehyde 5$B!>(Bhydroxylase (OsCAld5H1), which was effective in
modulating syringyl (S)/guaiacyl (G) lignin composition ratio in rice, a
model grass species. The OsCAld5H1$B!>(Bknockdown rice lines generated using
gene silencing, exhibited augmented G lignin units yet contained
considerable amounts of residual S lignin units. In their latest study, they
generated loss$B!>(Bof$B!>(Bfunction mutants of OsCAld5H1 using the CRISPR-Cas9
system to understand the effect of suppression of OsCAld5H1 on rice lignin
structure.

Results showed that all the tested mutant lines were enriched in G units and
produced considerable numbers of S units. Surprisingly, analysis showed that
enrichment of G units in lignins of the mutants was limited to the non$B!>&C!>(B
p$B!>(Bcoumaroylated units, while grass$B!>(Bspecific $B&C!>(Bp$B!>(Bcoumaroylated lignin
units were almost unaffected. Further analysis showed that no homologous
genes of OsCAld5H1 were overexpressed in the mutants. These data suggested
that CAld5H is mainly involved in the production of non$B!>&C!>(Bp$B!>(B
coumaroylated S lignin units, common in both eudicots and grasses, but not
in the production of grass$B!>(Bspecific $B&C!>(Bp$B!>(Bcoumaroylated S units in rice.

[onlinelibrary.wiley.com]