Protein analysis during almond embryo development. Identification and characterization of a late embryogenesis abundant protein

The expression pattern of proteins was analysed during late embryogenesis i n almond (Prunus amygdalus) to obtain information on the molecular events l eading to the acquisition of the embryo desiccation tolerance. Analysis of the ABA content in developing embryos revealed high levels at 50 DAF with a rapid decrease at the onset of desiccation. Two-dimensional electrophoresi s of proteins showed that at least ten different polypeptides were induced by dehydration of the embryos. By immunoscreening of a mature embryo cDNA e xpression library, the ABA inducible Parab21 cDNA (for P. amygdalus respons ive to ABA) encoding for a highly phosphorylated protein was isolated and c haracterized. Parab21 belongs to the LEA-D11 protein family, and contains a ll the protein motifs characteristic for the RAB/dehydrin group of proteins . The Parab21 mRNA is expressed during late embryogenesis and is also induc ible by water deficit and ABA treatment in vegetative tissues. Southern blo tting and mapping data are consistent with a single Parab21 gene in the alm ond genome although other immunologically-related proteins have been detect ed suggesting that a complex family of RAB/dehydrin-related genes will be i nvolved in desiccation tolerance in almonds. (C) 2000 Editions scientifique s et medicales Elsevier SAS.