The MADS-Domain Transcriptional Regulator AGAMOUS-LIKE15 Promotes Somatic Embryo Development in Arabidopsis and Soybean

The MADS-domain transcriptional regulator AGAMOUS-LIKE15 (AGL15) has been reported to enhance somatic embryo development when constitutively expressed. Here we report that loss-of-function mutants of AGL15, alone or when combined with a loss-of-function mutant of a closely related family member, AGL18, show decreased ability to produce somatic embryos. If constitutive expression of orthologs of AGL15 is able to enhance somatic embryo development in other species, thereby facilitating recovery of transgenic plants, then AGL15 may provide a valuable tool for crop improvement. To test this idea in soybean (Glycine max), a full-length cDNA encoding a putative ortholog of AGL15 was isolated from soybean somatic embryos. Subsequently, the corresponding genomic region of the gene was obtained. This gene, designated GmAGL15, encodes a protein with highest similarity to AGL15 from Arabidopsis (Arabidopsis thaliana) and Brassica napus that accumulates to its highest amount in embryos in these species. Like Arabidopsis and Brassica AGL15, GmAGL15 was preferentially expressed in developing embryos. When ectopically overexpressed the soybean protein was able to enhance somatic embryo development in soybean.