Co-silencing E1 and its homologs in an extremely late-maturing soybean cultivar confers super-early maturity and adaptation to high-latitude short-season regions

摘要

Soybean(Glycine max(L.) Merr.), a typical short-day plant, is sensitive to photoperiod, which limits the geographical range for its cultivation. In the flowering pathway regulated by photoperiod, E1, a flowering inhibitor in soybean, plays the dominant role in flowering time regulation. Two E1 homologs, E1-like-a(E1 La) and E1-like-b(E1 Lb), play overlapping or redundant roles in conjunction with E1. In the present study, E1 and E1 La/b were simultaneously silenced via RNA interference(RNAi) in Zigongdongdou(ZGDD), an extremely late-flowering soybean landrace from southern China. As a result, RNAi lines showed a much earlier-flowering phenotype and obvious photoperiod insensitivity compared with wild-type(WT) plants. In RNAi transgenic plants, the expression levels of flowering inhibitor GmFT4 and flowering promoters Gm FT2a/Gm FT5a were significantly down-and up-regulated, respectively. Further, the maturity group(MG) of the RNAi lines was reduced from WT ZGDD’s MG Ⅷ(extremely late-maturity) to MG 000(super-early maturity), which can even grow in the northernmost village of China located at a latitude of 53.5°N. Our study confirms that E1 and E1 La/b can negatively regulate flowering time in soybean. The RNAi lines generated in this study, with early flowering and maturity traits, can serve as valuable materials and a technical foundation for breeding soybeans that are adapted to high-latitude short-season regions.