Cloning and functional analysis of the flowering gene GmSOC1-like, a putative SUPPRESSOR OF OVEREXPRESSION CO1/AGAMOUS-LIKE 20 (SOC1/AGL20) ortholog in soybean.

KEY MESSAGE: The major insight in this manuscript is that we identified a new flowering regulator, GmSOC1-like, which may participate in the initiation and maintenance of flowering in soybean. Flowering is pivotal for the reproductive behavior of plants, and it is regulated by complex and coordinated genetic networks that are fine-tuned by endogenous cues and environmental signals. To better understand the molecular basis of flowering regulation in soybean, we isolated GmSOC1 and GmSOC1-like, two putative soybean orthologs for the Arabidopsis SUPPRESSOR OF OVEREXPRESSION OF CO1/AGAMOUS-LIKE 20 (SOC1/AGL20). The expression pattern of GmSOC1-like was analyzed by qRT-PCR in Zigongdongdou, a photoperiod-sensitive soybean cultivar. GmSOC1-like was widely expressed at different levels in most organs of the soybean, with the highest expression in the shoot apex during the early stage of floral transition. In addition, its expression showed a circadian rhythm pattern, with the highest expression at midnight under short-day (SD) condition. Intriguingly, GmSOC1-like was induced 4 days earlier than GmSOC1 during flowering transition in SD, suggesting that GmSOC1 and GmSOC1-like expression might be differentially regulated. However, under long-day (LD) condition, the expression of GmSOC1 and GmSOC1-like decreased gradually in the shoot apex of Zigongdongdou, which is in accordance with the fact that Zigongdongdou maintains vegetative growth in LD. In addition, overexpression of GmSOC1-like stimulated the flowering of Lotus corniculatus cv. supperroot plants. In conclusion, the results of this study indicate that GmSOC1-like may act as a flowering inducer in soybean.