LOCALIZATION OF A NUCLEAR-PROTEIN (QP47) IN EMBRYONIC MERISTEMS DURING SEED MATURATION AND GERMINATION AND ITS DISTRIBUTION AMONG CROP PLANTS

We report a desiccation-associated protein (QP47) which appears to be localized in the nucleoplasm of embryonic meristems during seed maturation and seed germination. The variations of nuclear localization shown by this protein during seed maturation and germination might depend upon the nuclear and nucleolar rearrangement following variations in moisture content in the seed tissues. The nucleolus is the compartment where the most obvious changes in chromatin organization take place. It is suggested that this protein has a role in the protection of the nucleus from desiccation. QP47 is present in nuclei of legumes, but not in cereals or recalcitrant seeds. In cereals, other nuclear proteins with a putative function similar to QP47 have been identified. The fact that the quantitative variations of QP47 seem to be unique to an embryonic stage of plant development suggests that this protein may act as an atypical desiccation protein with an additional function in storage. Such an additional storage function would also explain the restricted occurrence of QP47 to members of the Leguminosae.