Desiccation tolerance acquisition in developing beech (Fagus sylvatica L.) seeds: the contribution of dehydrin-like protein

摘要

The acquisition of desiccation tolerance (DT) in developing beech (Fagus sylvatica L.) seeds and the role of a dehydrin protein in this process were investigated. DT was determined by measurement of electrolyte leakage and germination capacity after drying to 10–12% moisture content (MC). In addition to mass maturity, the presence of heat-stable proteins, dehydrin accumulation and the peak of ABA content were measured in relation to the acquisition of DT. Mass maturity was achieved at 16 weeks after flowering (WAF). The germination capacity increased from 8% at 12 WAF to 80–90% after 16 WAF. Cell membrane integrity, measured as a decrease in electrolyte leakage after desiccation, was acquired at 16 WAF. Additionally, the ratio of heat-stable to soluble proteins was the highest at 16 WAF. One dehydrin-like protein with a molecular mass 44 kDa, named DHN44, was detected in embryonic axes at 16 WAF and in cotyledons at 17 WAF, and its gradual accumulation was observed in mature seeds. With regard to the acquisition of DT, the strongest correlations were detected between electrolyte leakage, DHN44 accumulation, and the percentage of heat-stable proteins. These results suggest that developing beech seeds become tolerant to desiccation at 16 WAF. The effect of desiccation and ABA treatment on DHN44 synthesis was tested before (14 WAF) and after the DT acquisition (18 WAF). Depending on the maturation stage desiccation and ABA treatment can induce or enlarge DHN44 expression.