Functional Evolution of Phosphatidylethanolamine Binding Proteins in Soybean and Arabidopsis

Abstract

Gene duplication provides resources for novel gene functions. Identification of the amino acids responsible for functional conservation and divergence of duplicated genes will strengthen our understanding of their evolutionary course. Here, we conducted a systemic functional investigation of phosphatidylethanolamine binding proteins (PEBPs) in soybean (Glycine max) and Arabidopsis thaliana. Our results demonstrated that after the ancestral duplication, the lineage of the common ancestor of the FLOWERING LOCUS T (FT) and TERMINAL FLOWER1 (TFL1) subfamilies functionally diverged from the MOTHER OF FT AND TFL1 (MFT) subfamily to activate flowering and repress flowering, respectively. They also underwent further specialization after subsequent duplications. Although the functional divergence increased with duplication age, we observed rapid functional divergence for a few pairs of young duplicates in soybean. Association analysis between amino acids and functional variations identified critical amino acid residues that led to functional differences in PEBP members. Using transgenic analysis, we validated a subset of these differences. We report clear experimental evidence for the functional evolution of the PEBPs in the MFT, FT, and TFL1 subfamilies, which predate the origin of angiosperms. Our results highlight the role of amino acid divergence in driving evolutionary novelty after duplication.

Soybean adaption to high‐latitude regions is associated with natural variations of GmFT2b, an ortholog of FLOWERING LOCUS T

“…To determine the subcellular localization of the GmFT2b protein in planta , we fused the GmFT2b coding region with the gene for green fluorescent protein (GFP) under the control of the constitutive cauliflower mosaic virus (CaMV) 35S promoter and transfected the resulting p35S::GmFT2b‐GFP plasmid into onion epidermal cells. Confocal microscopy showed that the GmFT2b protein is expressed in the cytoplasm and nucleus, with a stronger signal in the nucleus (Figure S2), similar to the cellular localization of the other functional phosphatidylethanolamine binding proteins in soybean (Wang et al, ).…”

“…Soybean is a diploid species that evolved from an ancient tetraploid, and its genome has undergone homologous chromosomal recombination and reassortment of the entire genome during its long evolutionary history (Wang et al, ). At present, it has been shown that the soybean genome encodes at least ten members of the GmFT gene family.…”

“…At least ten FT gene homologs have been identified in soybean (Kong et al, ). These FT genes are the result of tandem and whole genome duplications in soybean (Thakare, Kumudini, & Dinkins, ; Wang et al, ). Among these genes, GmFT2a and GmFT5a have been found to promote flowering following the expression of the phytochrome PHYA in soybean, and show the same relationship as AtFT and AtTSF ( TWIN SISTER of FT ) in Arabidopsis (Nan et al, ; Takeshima et al, ; Yamaguchi, Kobayashi, Goto, Abe, & Araki, ).…”

Functional diversification of Flowering Locus T homologs in soybean: GmFT1a and GmFT2a/5a have opposite roles in controlling flowering and maturation

“…S2). Confocal microscopy observations suggested that the GmFT1a‐GFP fusion protein was located in the nucleus and in the cytoplasm (Figs c, S2), which is consistent with the subcellular localization of the other functional PEBPs in soybean (Wang et al ., ).…”

Plasticity and innovation of regulatory mechanisms underlying seed oil content mediated by duplicated genes in the palaeopolyploid soybean

“…Duplicated genes can also be retained without functional changes to maintain their dosage balance (Birchler et al ., ; Veitia et al ., ; Birchler and Veitia, ). Some of these hypotheses above are supported by recent observations from soybean (Tian et al ., ; Du et al ., ; Wang et al ., ), but how genetic pathways or networks underlying a particular plant trait were modified following WGD have not been experimentally characterized.…”