Spartina alterniflora is rapidly spreading along the southeast
coast of China as an invasive species. However, the molecular mechanism
of its adaptation via high tillering to salt environment is unclear yet.
The objective of this study is to investigate the effect of salinity on
the underlying mechanism of strigolactone (SLs) signaling-mediated
tillering in S. alterniflora. The field transplant and greenhouse
experiments were set up, while the tillering processes under different
salinities were measured. The results showed that moderate (13-18‰, 15‰)
salinity promoted the outgrowth of S. alterniflora tiller than
control (0-6‰, 0‰) and high salinity (29-32‰, 30‰). Furthermore, the
content of strigolactones (SLs) and the genes involved in SLs
biosynthesis (D10, D17) ＆ signaling (D14,
D53) were analyzed on the seedlings grown in greenhouse. The SLs
content in roots was reduced with the increase of salinity, which
resulted from the down-regulation of SaD10 and SaD17
expression. In addition, moderate salinity (15‰) down-regulated
SaD14 and up-regulated SaD53 expression, while these gene
expressions exhibited different under the control salinity (0‰) and high
salinity (30‰). In conclusion, our data revealed that 15‰ salinity
promoted the tillering process by depressing the SLs level via
inhibiting SLs biosynthesis and perception, but activating the
expression of a repressor in SLs signaling in S. alterniflora.
The conclusion can help us to understand the mechanism of fast invasion
of S. alterniflora into new intertidal salt habitats.