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
- Journal of Integrative Agriculture 2022年02期
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.
1. Introduction 2. Materials and methods 2.1. Plant materials and growth conditions 2.2. E1 cloning and RNAi vector construction 2.3. Soybean transformation and identification of transgene-positive plants 2.4. Gene expression analysis 2.5. Phenotyping and statistical analysis 2.6. Maturity group classification 3. Results 3.1. RNAi-mediated down-regulation of E1 and E1La/b expression resulted in flowering promotion 3.2. RNAi lines exhibited high expression levels of Gm FT2a/5a but low expression levels of Gm FT4 3.3. Photoperiod sensitivity was significantly decreased in RNAi lines 3.4. RNAi lines were reclassified as an extremely-early MG 4. Discussion 5. Conclusion Declaration of competing interest