Silencing of the glutathione biosynthetic pathway inhibits somatic embryogenesis in wheat

Abstract

Somatic embryogenesis in scutella of wheat (Triticum aestivum L.) is a well documented phenomenon and it has been shown through transcriptome analysis that genes involved in antioxidant responses, particularly in glutathione (GSH) biosynthesis, participate in the process. Thus, we investigated the influence of post-transcriptional silencing (PTGS) of the glutathione biosynthesis genes GSH1 and GSH2 on somatic embryogenesis in wheat. We found that PTGS of either of the target genes drastically inhibits callus regeneration and overall efficiency of transformation, in a similar manner as the GSH biosynthetic inhibitor buthionine sulfoximine. Supplementing the medium with glutathione did not overcome the observed low efficiency of wheat transformation. Furthermore, of the small number of obtained transformants, none exhibited altered GSH1 and GSH2 levels of transcription. Thus, it is concluded that GSH is essential for somatic embryogenesis and, as a consequence, it is difficult to regenerate wheat plants with silenced GSH1 and GSH2 genes.