Junya Wang, Xin Xu, Peiguo Wang, Lixin Zhang, Lifeng Liu, Luping Liu, Tingting Wu, Wenwen Song, Shan Yuan, Bingjun Jiang, Wensheng Hou,  Cunxiang Wu, Shi Sun, Lijie Yu, Tianfu Han

Plant Cell & Environment; 2024; IF:7.3

DOI: 10.1111/pce.14833

Abstract

Soybean (Glycine max) is a typical short day plant (SDP), but has been widely cultivated in high-latitude long day (LD) regions because of the development of early-maturing genotypes which are photoperiod-insensitive. However, some early-maturing varieties exhibit significant responses to maturity under different day lengths but not for flowering, depicting an evident photoperiodic after-effect, a poorly understood mechanism. In this study, we investigated the post-flowering responses of 11 early-maturing soybean varieties to various pre-flowering photoperiodic treatments. We confirmed that pre-flowering SD conditions greatly promoted maturity and other post-flowering developmental stages. Soybean homologs of FLOWERING LOCUS T (FT), including GmFT2a, GmFT3a, GmFT3b, and GmFT5a, were highly accumulated in leaves under pre-flowering SD treatment. More importantly, they maintained a high expression level after flowering even under LD conditions. E1 RNAi and GmFT2a overexpression lines showed extremely early maturity regardless of pre-flowering SD and LD treatments due to constitutively high levels of floral-promoting GmFT homolog expression throughout their lifecycle. Collectively, our data indicate that high and stable expression of floral-promoting GmFT homologs play key roles in maintenance of photoperiodic induction to promote post-flowering reproductive development, which confers early-maturing varieties with appropriate vegetative growth and shortened reproductive growth periods for adaptation to high-latitudes.