Sacred lotus is rich in biologically active compounds, particularly benzylisoquinoline alkaloids (BIAs). Here, we report on isolation of genes encoding (S)-norcoclaurine synthase (NCS) in sacred lotus, which is a key entry-enzyme in BIA biosynthesis. Seven NCS genes, designated NnNCS1 through NnNCS7, were identified in the sacred lotus genome, and five are located next to each other within a 83 kb region on scaffold 8. The NCS genes are divided into two subfamilies, designated NCSI and NCSII. The NCSII genes are universal in plants, while the NCSI genes are only identified in a limited number of dicotyledonous taxa that produce BIAs. In sacred lotus, only NnNCS4 belongs to the NCSII subfamily, whilst the rest NCS genes within the NCSI subfamily. Overall, the NnNCS7 gene was predominantly expressed in all tested tissues, and its expression is significantly correlated with alkaloid content in leaf. In contrast, the NnNCS4 expression shows no significant correlation with alkaloid accumulation in leaf, and its lack of expression cannot inhibit alkaloid accumulation. Taken together, these results suggest that the NCSI subfamily is crucial for BIA biosynthesis, and its origin may represent an important evolutionary event that allows certain plant taxa to produce BIAs.
Lotus (
Nelumbo nucifera
Gaertn.) contains various bioactive
compounds, with benzylisoquinoline alkaloids (BIAs) as one of the
major groups. The biosynthetic pathways of two major bioactive BIAs
in this plant, nuciferine and
N
-nornuciferine, are
still not clear. Therefore, several genes related to BIA biosynthesis
were searched from the lotus database to study the role of key genes
in regulating these pathways. In this study, the expression profiles
of
NCS
,
CNMT
, 6
OMT
,
CYP
80
G
2, and
WRKY TFs
were investigated in mechanically wounded lotus leaves. It was found
that the accumulation of nuciferine and
N
-nornuciferine
significantly increased in the mechanically wounded lotus leaves in
accordance with the relative expression of putative
CYP
80
G
2 and one WRKY transcription factor (
NNU_
24385), with the coregulation of
CNMT
. Furthermore, the role of methyltransferase-related genes in this
study suggested that methylation of the isoquinoline nucleus to yield
a methylated-BIA structure may occur at the N position before the
O position. Altogether, this study provides improved understanding
of the genes regulating BIA biosynthesis under stressed conditions,
which could lead to improvements in BIA production from the commercial
lotus.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.