STENOFOLIA gene and regulation of somatic embryogenesis in Medicago truncatula

Resumo

Expression of STENOFOLIA (STF) gene was analyzed in different organs of line R-108 barrel medic plants (Medicago truncatula Gaertn.). Maximum levels of STF expression were observed in the generative organs, fruits and flowers, suggesting its involvement in the reproduction process. The local analysis of STF expression during somatic embryogenesis in M. truncatula showed that the STF promoter is activated directly in somatic embryos. Overexpression of STF gene in the calli of R-108 line leads to increased embryogenicity, accompanied by reduced levels of MtGH3.6 gene expression, which is responsible for auxin metabolism, and also reduced expression levels of gene encoding MtHB1 transcription factor. Comparative analysis of MtGH3.6 and MtHB1 gene expression dynamics in the calli of embryogenic 2HA line and non-embryogenic A17 line of M. truncatula showed that these genes demonstrated reduced level of expression in embryogenic calli compared to non-embryogenic. These data suggested that STF stimulates the formation of somatic embryos, directly or indirectly inhibiting the transcription of MtGH3.6, MtHB1 and, probably, many other genes.