AUTHOR=Yuan Shan , Wang Yining , Wang Junya , Zhang Chunlei , Zhang Lixin , Jiang Bingjun , Wu Tingting , Chen Li , Xu Xin , Cai Yupeng , Sun Shi , Chen Fulu , Song Wenwen , Wu Cunxiang , Hou Wensheng , Yu Lijie , Han Tianfu 

TITLE=GmFT3a fine-tunes flowering time and improves adaptation of soybean to higher latitudes

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.929747

DOI=10.3389/fpls.2022.929747

ISSN=1664-462X

ABSTRACT=<p>Onset of flowering of plants is precisely controlled by extensive environmental factors and internal molecular networks, in which <italic>FLOWERING LOCUS T</italic> (<italic>FT</italic>) is a key flowering integrator. In soybean, a typical short-day plant, 11 <italic>FT</italic> homologues are found in its genome, of which several homologues are functionally diversified in flowering pathways and the others including <italic>GmFT3a</italic> are yet unknown. In the current study, we characterized <italic>GmFT3a</italic>, which is located on the same chromosome as the flowering promoters <italic>GmFT2a</italic> and <italic>GmFT5a</italic>. Overexpression of <italic>GmFT3a</italic> significantly promoted flowering of Arabidopsis under the inductive long-day (LD) photoperiod. <italic>GmFT3a</italic> over-expressed soybean also flowered earlier than the control under LD, but they were not significantly different under inductive short-day (SD) conditions, indicating that <italic>GmFT3a</italic> acts as a flowering promoter in the non-inductive photoperiod in soybean. Compared with other <italic>GmFT</italic> homologues, <italic>GmFT3a</italic> exhibited a slighter effect in flowering promotion than <italic>GmFT2a</italic>, <italic>GmFT5a</italic> and <italic>GmFT2b</italic> under LD conditions. <italic>GmFT3a</italic> promoted flowering by regulating the expression of downstream flowering-related genes and also affected the expression of other <italic>GmFTs</italic>. According to the re-sequencing data, the regional distributions of two major haplotypes in 176 soybean varieties were analyzed. The varieties with <italic>GmFT3a</italic>-Hap2 haplotype matured relatively early, and relative higher expression of <italic>GmFT3a</italic> was detected in early maturing varieties, implying that Hap2 variation may contribute to the adaptation of soybean to higher latitude regions by increasing expression level of genes in metabolism and signaling pathways. The early flowering germplasm generated by overexpression of <italic>GmFT3a</italic> has potential to be planted at higher latitudes where non-inductive long day is dominant in the growing season, and <italic>GmFT3a</italic> can be used to fine-tune soybean flowering and maturity time and improve the geographical adaptation.</p>