Gene expression of late embryogenesis abundant proteins, small heat shock proteins and peroxiredoxin and oxidation of lipid and protein during loss and re-establishment of desiccation tolerance in Pisum sativum seeds

The aim of the present work was to investigate the mechanism of loss and re-establishment of desiccation tolerance (DT) in germinated Pisum sativum seeds (seedlings). Dehydration of pea seedlings of 2 mm radicle length was accompanied by concomitant loss of DT from 100 to 60 and 20% when dehydrated to initial water content (IWC) and below IWC, respectively. Desiccation of seedlings was associated with accumulation of malondialdehyde (MDA) and carbonyls (oxidized product of lipid and protein, respectively) with increased solute leakage and decreased seedling viability. Also, the transcripts of all the protective proteins like late embryogenesis abundant proteins (LEA; PsDHN2, PsDHN3 and PsSBP65), small heat shock proteins (sHSP; PsHSP17.7, PsHSP18.1, PsHSP18.2 and PsHSP22.7) and peroxiredoxin (Prx; 2-Cys Prx) increased in seedlings desiccated to IWC but massive loss (5- to 9-folds) was discernible when desiccated below IWC. The PEG pre-treatment re-established the DT from 20 to 70% in seedlings dehydrated below IWC. The re-induction of DT in PEG-treated seedlings was accompanied with enhanced seedling viability and gene expression (5- to 10-folds) of all the protective proteins (LEA, sHSP and 2-Cys Prx) with substantial reduction in the levels of MDA, carbonyls and electrolyte leakage. The role of genes encoding the protective proteins, MDA, carbonyls, TTC reduction and solute leakage was discussed during loss and re-establishment of DT in pea seedlings.