The effect of H2O2 and abscisic acid (ABA) interaction on β-amylase activity under osmotic stress during grain development in barley

The effects of exogenous abscisic acid (ABA) and polyethylene glycol (PEG 6000) treatments on grain H2O2, ABA and β-amylase activity were studied during grain development in the spike culture experiments with variety Triumph and its ABA-insensitive mutant TL43 as the plant materials. The results showed that during grain development the two genotypes were similar in the pattern of ABA concentration change, but differed greatly in the pattern of H2O2 concentration and β-amylase activity changes. The β-amylase activity was positively correlated with H2O2 concentration, negatively correlated with ABA concentration, and it is mainly closely associated with continued high levels of ABA with respect to H2O2. Water stress (PEG treatment) induced β-amylase was associated with H2O2 concentration but not with ABA concentration. Exogenous application of H2O2 and Ascorbic acid (AsA) increased β-amylase activity in Triumph but reduced that of TL43. However, the endogenous H2O2 concentration in grains was always consistent with β-amylase activity. A novel model was hypothesized from the current results to illustrate the relationship between H2O2, ABA and β-amylase synthesis for the barley exposed to abiotic stresses.