Changes in the Electrophoretic Patterns of the Soluble Proteins of Winter Wheat and Rye following Cold Acclimation and Desiccation Stress

Abstract

The degrees of freezing tolerance acquired by winter wheat (Triticum aestivium L.) and rye (Secake cereale L. cv Puma) were similar following a 4-week cold conditioning and a 24-hour desiccation stress. Soluble proteins were extracted from shoots of cold-conditioned or desiccation-stressed seedlings and electrophoresed on sodium dodecyl sulfate-polyacrylamide gels. Quantitative changes in the electrophoretic patterns of the soluble proteins of the different cultivars grown in different environments were detected, but the changes were not equivalent following cold conditioning and desiccation stress. The abundance of two polypeptide bands showed a significant increase correlated to the degree of freezing tolerance and, hence, the polypeptides in these bands may play a role in the development of freezing tolerance.The plasma membrane has been suggested as the primary site of frost and plasmolysis dehydration injury of plant cells (7,16,18,19). The mechanism by which the membrane of hardy cells tolerates more freezing and dehydration is not fully known but could be related to the general observation that metabolites accumulate in plant cells during hardening (17), a condition called augmentation of protoplasm (16).The amount of soluble proteins increases in cold and desiccation-hardened plants (2,4,15) and soluble proteins during cold hardening also undergo changes in electrophoretic mobility (1,5,6,(9)(10)(11)(12)14). Soluble protein fractions with apparent mol wt of 240,000 and 115,000 in wheat (14) NaOCl for 3 min and imbibed at 21 or at 2'C (cold conditioned) for 6 h. Seeds were germinated on moist fiter paper in the dark for 2.0 to 2.5 d at 24°C or for 4 weeks at 2°C (cold-conditioned). Seedlings were desiccation stressed by placing them for 24 h at 21°C over H2SO4 solution of 40% RH (3) and were reimbibed by immersion in aerated tap water for 24 h at 9°C.Evaluation of Freezing Tolerance. Water was removed from the surface of seedlings by blotting with filter paper. Seedlings were frozen in groups of 25 in Petri dishes. Cooling rates were 1°C/h from 0 to -21°C and 3°C/h from -21 to -30°C. Some of the seedlings were further cooled to -40°C for 1 h and put on Dry Ice for 1 h additional. Samples were seeded with ice crystals at -3°C to avoid supercooling. Frozen samples were thawed at 2°C for 1 h. Survival of excised epicotyls was assessed by the method we described in a previous paper (3).Soluble Protein Extraction and Determination. For each preparation of soluble proteins, 20 shoots were cut from fresh seedlings and weighed. Proteins were extracted by homogenization of the tissues in 0.1 M Tris-HCl (pH 7.0) at 0°C with a Polytron homogenizer and determined according to Siminovitch et al. (16).Electrophoresis and Calculation of Relative Abundance of Polypeptides. TCA-precipitated soluble proteins were solubilized in the final sample buffer of Laemmli (13) and electrophoresed on 1% SDS-10% polyacrylamide discs (13). Gels were stained with Coomassie blue (8) and gel scans were done at 570 nm on a compute...

The Effects of Salt on the Pattern of Protein Synthesis in Barley Roots

“…A similar response in the pattern of protein synthesis has been observed for excision shock (32). For other environmental stresses the response is not as dramatic; however, water stress (2,7,18,31), osmotic shock (13), wounding (8,29,30), cold acclimation (5,17,33,34), and salt stress (12, 31) result in an increase in the net synthesis of some proteins and a decrease in the synthesis of others, with or without a concomitant induction of unique stress proteins.We have initiated studies to analyze the influence of salt stress on the pattern of protein synthesis in barley roots. Barley is the most salt tolerant grain of major agricultural importance and has been grown in fields salted-out by previous irrigation practices (1 1, 25).…”

Protein Synthesis in Bromegrass (Bromus inermis Leyss) Cultured Cells during the Induction of Frost Tolerance by Abscisic Acid or Low Temperature

“…However, little is understood about the effects of low temperature or ABA on protein synthesis or gene expression. Electrophoretic analysis ofproteins synthesized during cold hardening of winter wheat, rye (7,23), rape (13,17), and mulberry trees (28) has shown increased or decreased synthesis of certain proteins in hardier varieties. The relationship of most of these proteins to freezing resistance in plants is probably equivocal, since other complicating processes such as vernalization, dormancy, adjustment to low temperature growth and development occur concomitantly.…”

Drought-Induced Changes in Protein Patterns of Brassica napus var. oleifera Roots

“…Newly synthesized proteins (13) and quantitative changes in protein patterns have already been mentioned in response to osmotic shock (3) or nonphysiological desiccation stress (5). However, changes under progressive dehydration have been reported only one other time, in the leaves ofXerophyta villosa, a desiccation tolerant Angiosperm, but the qualitative or quantitative nature of these modifications remains unclear (26).…”