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Abstract
The function of euAP1 and euFUL in AP1/FUL lineage have been well characterized in
core eudicots, and they play common and distinct roles in plant development. However,
the evolution and function of FUL-like genes is poorly understood in basal eudicots.
In this study, we identified three FUL-like genes PlacFL1/2/3 from London plane (Platanus
acerifolia). Sequence alignment and phylogenetic analysis indicated that PlacFL1/2/3
are AP1/FUL orthologs and encoded proteins containing FUL motif and paleoAP1 motif.
Quantitative real-time PCR (qRT-PCR) analysis showed that PlacFL1/2/3 were expressed
in both vegetative and reproductive tissues, but with distinct spatiotemporal patterns.
In contrast to PlacFL1 and PlacFL3, PlacFL2 exhibited higher expression levels and
broader expression regions, and that the expression of PlacFL2 gene showed a decreasing
and increasing tendency in subpetiolar buds during dormancy induction and breaking,
respectively. Overexpression of PlacFLs in Arabidopsis and PlacFL3 in tobacco resulted
in early flowering, as well as early termination of inflorescence meristems for transgenic
Arabidopsis plants. The expression changes of flowering time and flower meristem identity
genes in transgenic Arabidopsis lines with different PlacFLs suggested that PlacFL2
and PlacFL3 may regulate different downstream genes to perform divergent functions.
Yeast two-hybrid analysis indicated that PlacFLs interacted strongly with PlacSEP
proteins, and PlacFL3 instead of PlacFL1 and PlacFL2 could also form a homodimer and
interact with D-class proteins. Our results suggest that PlacFLs may play conserved
functions in regulating flowering and flower development, and PlacFL2 might also be
involved in dormancy regulation. The research helps us to understand the functional
evolution of FUL-like genes in basal eudicots, especially in perennial woody species.