Biology Reference
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the CYC-like gene expression does not positively correlate with the ventral sta-
men abortion (Preston et al., 2009). These facts inconsonant in the expression
data of ECE-CYC2 clade TCP genes imply that the ventral stamen abortion
might have evolved by convergent genetic mechanisms in different lineages of
Lamiales s.l. It merits further research in function and upstream regulatory
pathway to determine how the expression divergence is caused among paral-
ogues of OpdCYC in Opithandra. In addition, since the diverse variations
of zygomorphy in Lamiales s.l. might have involved independent shifts in
stamen number [3,21], further investigation of expression pattern and func-
tional analyses of CYC-like genes with identification of their upstream cis- or
trans-regulators as well as research in finding other factors possibly coopted to
this regulatory pathway in more zygomorphic groups would shed new lights
on the mechanisms that underlie the vast morphological diversity of zygomor-
phy in Lamiales s.l.
Conclusion
As the first to document the expression domain of ECE-CYC clade genes in
the ventral stamens, we here report that the expressions of OpdCYC genes are
correlated with abortion of both dorsal and ventral stamens in Opithandra,
strengthened by the negatively correlated expression of their putative direct
target OpdcyclinD3 genes. The complement of OpdcyclinD3 to OpdCYC
gene expressions further indicates that OpdCYC expressions are related to
the dorsal and ventral stamen abortion through the negative effect on Opdcy-
clinD3 genes. The novel patterns of CYC-like gene expressions in Opithandra,
along with previous reports, suggest that ECE-CYC2 clade TCP genes are not
only functionally conserved in the dorsal stamen repression, but also involved
in arresting ventral stamens, a genetic mechanism underlying the establish-
ment of zygomorphy with abortion of both the dorsal and ventral stamens
evolved within Lamiales s.l.. It would be important to further find whether
ECE-CYC2 clade TCP genes are recruited repeatedly for arresting ventral
stamens and (or) whether there is any other genetic pathways underlying the
ventral stamen abortion, independently or interacting with ECE-CYC2 clade
TCP genes, in different lineages of Lamiales s.l.
Methods
Plant Materials
All materials used in this study, including gene cloning, in situ hybridization and
RT-PCR, were collected from the wild fields, i.e. Dinghu Mountains, Guangdong
