Cloning and Expression Analysis of the Soybean CO-Like Gene GmCOL9

Photoperiod is one of the important environmental triggers of flowering, and the CONSTANS (CO) gene is a key regulator of this pathway in the model plant Arabidopsis thaliana. CO-like genes are present in many plant species. We describe here the isolation of the CO homolog Glycine max CONSTANS-like 9 (GmCOL9) from the soybean cultivar Kennong18. Sequence comparisons showed that the closest A. thaliana gene to GmCOL9 is COL13. The expression of GmCOL9 was investigated using quantitative real-time reverse transcriptase polymerase chain reaction, which showed that GmCOL9 was not regulated by a circadian mechanism, since its expression oscillated at a cycle of 12 h instead of 24 h. GmCOL9 expression was influenced by the developmental stage of the plant and varied between tissue/organs. The expression of GmCOL9 was concentrated in the unifoliolate leaves during the vegetative phase of growth and in the stem during the reproductive phase. However, traces of expression were also present throughout the plant, indicating that GmCOL9 may be a multifunctional gene in the context of the development of the soybean plant.