Seasonal changes in a dehydrin-like protein and proteases of Pistacia vera inflorescence buds

Proteins associated with dormancy were isolated from reproductive buds of pistachio (Pistacia vera L.). A 32 kDa protein (IBP32) and a 27 kDa protein (IBP27), which are the major proteins in the bud and bark, were purified. They were characterized as glycoproteins rich in glycine and alanine and were highly hydrophilic. Immunological cross-reactivity between dehydrin antibodies and the IBPs, sequence homology and amino acid composition indicated that these proteins are dehydrin-Iike. The results suggest that IBP32 may play a role in stress tolerance, particularly in the cold hardiness of pistachio during dormancy, in addition to its function as a nitrogen reserve. In autumn, prior to dormancy, there is accumulation of proteins in inflorescence buds and bark of Pistacia vera L. Their concentration is high throughout winter and they disappear rapidly in early spring. A proteolytic activity specifically directed against IBP32 and IBP27 was extracted from pistachio inflorescence buds with peak activity at the beginning of bud opening and flowering. It is suggested that the proteolytic activity is important in mobilization of the nitrogen reserves stored in bud and bark storage proteins during dormancy to support new growth in spring.