Involvement of O2·− in the regulation of Polycomb, Trithorax and LEC1, L1L, WUS, WOX5, STM gene expression during somatic embryogenesis induction in M. truncatula

Abstract

2,4-dichlorophenoxyacetic acid (2,4-D), an auxinic herbicide, in many in vitro somatic embryogenesis systems is used to induce embryogenesis. This compound present at a low concentration (0.5 µM) during the induction phase, is necessary for M. truncatula embryogenic callus formation and, consequently, for embryo development. 2,4-D in higher concentration (5 µM) causes an increase in O 2 ·− accumulation which disturbs the callus and embryos formation. However, above processes are disturbed by DPI, an inhibitor of the NADPH oxidase responsible for the O 2 ·− production. Thus, the aim of this study was to elucidate whether during first week of induction phase the change in the level of O 2 ·− affects the expression of genes encoding Polycomb and Trithorax group proteins and the transcription level of some marker genes for SE. The expression of Polycomb and Trithorax group genes, and coding the transcription factors such as: LEC1, L1L, WUS, WOX5 and STM depends on the O 2 ·− accumulation in explant cells. Disorder of its level by manipulation of the concentration of 2,4-D or DPI disrupts expression of the above-mentioned genes and causes disturbances in the callus growth and development of somatic embryos.