SOC1 and LFY function in floral induction in
rice and Arabidopsis
SOC1 and LFY in Arabidopsis are the most important
integrators for flowering response and have long been
studied for their function in meristems [41]. Arabidopsis
SOC1 strongly promotes flowering. SOC1 expression
increases in the apical meristem, and this upregulation
requires FT activity [42].SOC1mis-expression from the
phloem-specificSUC2promoter can only weakly rescue
the soc1 mutation, suggesting that SOC1 acts mainly in
the meristem and has limited activity in leaves [43]. By
contrast, riceOsMADS50, a homolog of ArabidopsisSOC1,
has a clearly different mode of function.OsMADS50acts
in leaves upstream of RFT1 [15
]. The osmads50
mutation abolishesEhd1andRFT1expression in leaves,
causing a non-flowering phenotype during LD.
OsMADS50expression is very low in the meristem, and
its expression is unaffected by the floral transition. Thus,
Arabidopsis SOC1 acts as the floral integrator in the
meristem downstream of FT, but its rice homolog,
OsMADS50, defines the LD-specific flowering pathway
and acts as the upstream regulator ofRFT1in leaves