GmIDD Is Induced by Short Days in Soybean and May Accelerate Flowering When Overexpressed in Arabidopsis via Inhibiting AGAMOUS-LIKE 18

Photoperiod is one of the main climatic factors that determine flowering time and yield. Some members of the INDETERMINATE DOMAIN (IDD) transcription factor family have been reported to be involved in regulation of flowering time in Arabidopsis, maize, and rice. In this study, the domain analysis showed that GmIDD had a typical ID domain and was a member of the soybean IDD transcription factor family. Quantitative real-time PCR analysis showed that was induced by short day conditions in leaves and regulated by circadian clock. Under long day conditions, transgenic Arabidopsis overexpressing flowered earlier than wild-type, and mutants flowered later, while the overexpression of rescued the late-flowering phenotype of mutants. Chromatin immunoprecipitation sequencing assays of binding sites in Arabidopsis further identified potential direct targets, including a transcription factor, ( ). might inhibit the transcriptional activity of flower repressor by binding to the motif of promoter. Furthermore, the results also showed that overexpression increased the transcription levels of flowering time-related genes ( ), ( ), ( ) and ( ) in Arabidopsis. Taken together, appeared to inhibit the transcriptional activity of and induced the expression of gene to promote Arabidopsis flowering.