Changes in gene expression and soluble carbohydrate contents during the imbibition and re-induction of Desiccation tolerance in Peltophorum dubium seeds

Desiccation tolerance (DT) is the capacity of organisms to tolerate drying and rehydration without losing viability. DT is induced during orthodox seed development and usually lost during germination. Here we show that Peltophorum dubium seeds lose DT at the end of germination when its radicle protrudes and that DT can be re-induced in this species by the application of the plant hormone abscisic acid under a low temperature regime. The re-induction of DT in P. dubium seeds coincides with the accumulation of transcripts of a putative superoxide dismutase and a heat shock protein indicating that protection against reactive oxygen species and coordinated protein folding might be key features in the maintenance of DT. Furthermore, we explored the soluble sugar content of dry, germinating and DT-re-induced seeds. Dry seeds had high sugar content, which reduced during germination indicating a relationship between sugar content and the loss of DT. However, DT-reinduced seeds did not accumulate soluble sugars indicating either that those sugars are not required in the re-induction of DT in P. dubium seeds or that the low contents reached during germination are still sufficient to guarantee the protection during and after drying and an increase in their contents was not needed.