Maturity time is an essential phenotypic measure of ecological adaptability of soybean and an important trait related to its yield formation. The study of promoters and expression patterns of major maturity genes E1 and E2 would provide basis for the study of gene function and molecular regulatory network of maturity time and lay foundation for adaptability improvement and yield increase in soybean.

The promoter sequences of major maturity genes E1 and E2 were analyzed through the promoter cis-element analysis website PlantCARE, and the important regulatory elements were detected. The promoters of E1 and E2 were cloned, the GUS vectors were constructed, and transformation of Arabidopsis was performed to detect GUS activity in different tissues and organs of transgenic plants. Under low light and strong light conditions, the expression levels of E1 and E2 were compared between long day and short day conditions. The expression levels of E1 and E2 were detected in soybean varieties of different maturity groups, which is for the analysis of correlation between expression levels and maturity time of soybean varieties.

Both E1 and E2 promoters contained multiple photoresponsive elements such as AE-box, Box4 and G-box, E1 promoter also contained auxin-response, abolic acid-response elements, and E2 promoter also contained low temperature-response, drought-response elements and meristem expression elements. In GUS activity detection of transgenic Arabidopsis, E1 promoter had strong transcriptional activity in all organs of the plant, and transcriptional activity of E2 promoter in fibrovascular tissues of seedling hypocotyl, leaf and root was relatively strong. Under both low light and strong light conditions, the expression level of E1 was significantly higher in long day than in short day. Under low light conditions, the expression level of E2 was higher in short day than in long day. Under strong light conditions, the expression level of E2 was higher in long day than in short day. With the increase of maturity time of different soybean varieties, expression level of E1 increased gradually, while E2 expression level did not change regularly.

The promoter of E1 gene was a widely expressed promoter, and its expression level was significantly regulated by photoperiod and significantly correlated with the maturity time of soybean varieties. The promoter of E2 was strongly expressed in vascular tissues of various organs, the photoperiodic regulation mode of this gene was different under strong light and low light conditions, and there was no significant correlation between expression level of E2 and maturity time.