Identification of diversified functions of soybean FT homologs in photoperiod-dependent flowering time control

  • Lee, Su Hyeon (Division of Applied Life Science (BK21 Plus), Institute of Agriculture & Life Science, Gyeongsang National University) ;
  • Choi, Cheol Woo (Division of Applied Life Science (BK21 Plus), Institute of Agriculture & Life Science, Gyeongsang National University) ;
  • Kim, Min Chul (Division of Applied Life Science (BK21 Plus), Institute of Agriculture & Life Science, Gyeongsang National University)
  • Published : 2017.06.04

Abstract

FT is one of the major floral activator in plant flowering. FT determines the changing point of time from vegetative stage to reproductive stage. To understand the role of FT homologs in short-day plant soybean, we identified 10 soybean FT homologous genes and named GmFTs. We figured out that 10 GmFT genes were further categorized into three subclades through phylogenetic analysis. Expression analysis of GmFT genes indicated that they might have different functions in photoperiod-dependent soybean flowering. Most of GmFTs, for example, GmFT2a, GmFT2b, GmFT5a and GmFT6 mainly expressed in soybean leaves at short-day condition. However, interestingly GmFT1a and GmFT4 represented opposite expression pattern to other GmFTs. Arabidopsis transgenic plants overexpressing GmFT2a and GmFT5a exhibited extremely early flowering. In contrast, overexpression of GmFT4 delayed flowering of Arabidopsis transgenic plants. The results suggest that GmFT4 has antagonistic role to other GmFTs in soybean flowering. Interestingly, mRNA level of GmFT2a is higher in early flowering soybean accessions than in late flowering ones. Moreover, the highest point of mRNA level of GmFT2a showed the positive correlation with the timing of flowering of soybean accessions. But that of GmFT4 showed opposite pattern. Here, we report that soybean FT homologs might acquire different functions in photoperiod-dependent flowering through the functional diversification during evolution.

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