Cellular Concentrations and Uniformity of Cell-Type Accumulation of Two Lea Proteins in Cotton Embryos.

Abstract

The levels and cell-type distribution of late embryogenesis abundant (Lea) proteins D-7 and 0-113 have been determined in mature cotton embryos by immunochemical methods. The two proteins were expressed in and purified from Escherichia coli and utilized for antibody production in rabbits. The antiserum to each protein was found to interact with all members of each protein family in cotton extracts by protein gel blotting. Using these antibodies in quantitative "rocket" immunoelectrophoreses, D-7 proteins were found to accumulate to -8 x 1015 molecules per embryo, which is equivalent to mlO9 molecules per "average cell." D-113 proteins accumulate to ~1 0~6 molecules per embryo, which equates to 4 . 3 x 109 molecules per average cell. These values calculate to concentrations of about 226 and 283 pM, respectively, in the cell aqueous phase immediately prior to seed desiccation. In immunocytochemical studies using the fluorophor rhodamine linked to the secondary antibody, both proteins appeared to be evenly present in the cytosol of all cell types present in the embryo, including both cotyledon and axis epidermal cells. Thus, their function does not appear related to unique functions of specific cell or tissue types. The very high molar concentrations of the two proteins, coupled with their unusual predicted structure and their cytosol location, would seem to reduce the number of their conceivable functions.

Cloning and characterization of differentially expressed genes in imbibed dormant and afterripened Avena fatua embryos

“…This is consistent with the previous findings [18,31]. It has been hypothesized that LEA proteins may have a protective role during water loss [8,9,34]. Considering the universal occurrence of LEA proteins in higher plants the differential expression of LEA genes in dormant and afterripened embryos may be a result of germination.…”

Expression, tissue distribution and subcellular localization of dehydrin TAS14 in salt-stressed tomato plants

“…The distinct pattern of tissue distribution of TAS 14 in salt-stressed plants contrasts with the more uniform distribution reported for maize Rabl7 [16] and other unrelated Lea proteins in embryos [36]. This fact, together with the agedependent organ specificity discussed above, indicates a progressive restriction of the expression of these genes upon germination and further development that may reflect a phase shift from embryonic to vegetative gene expression programmes.…”

Transformation of tomato cultivar ‘Pusa Ruby’ with bspA gene from Populus tremula for drought tolerance

“…They are involved in protection of enzymes against desiccation and structural proteins by protein-protein interactions. These interactions prevent the irreversible structural changes that occur in many proteins during water stress (Dure, 1993;Roberts et al, 1993). Such proteins function as water binding proteins, preventing complete water loss from membranes, and in sequestering excess ions, which accumulate in desiccated cells (Ingram and Bartels, 1996;Caruso et al, 2002).…”