Changes in Protein Synthesis in Rapeseed (Brassica napus) Seedlings during a Low Temperature Treatment

Abstract

ABSTRACI?Changes induced by cold treatment in young rapeseed (Brassica napus) seedlings were investigated at the molecular level. Following germination at 18°C for 48 hours, one half of the seedlings was transferred to 0°C for another 48 hour period, the other half being kept at 18°C as a control. Newly synthesized proteins were labeled for the last 6 hours of incubation with I35Simethionine. The different polypeptides were separated by twodimensional electrophoresis in polyacrylamide gels. Newly synthesized proteins were revealed by fluorography. Protein synthesis clearly continues at 0°C and some polypeptides preferentially accumulate at this temperature. On the other hand, synthesis of several others is repressed while many are insensitive to cold treatment. Similar changes are also observed when mRNA is prepared from cold treated seedlings, translated in vitro in a reticulocyte cell free system and compared with the products of mRNA extracted from control samples. Among the genes which are repressed we identified the small subunit of ribulose 1,6-bisphosphate carboxylase. These changes are also detectable after shorter treatments.During the last few years, it has been demonstrated that higher plants are able to respond to various environmental changes by inducing the synthesis of specific proteins. The best known examples are the induction of heat shock proteins (10,11,17) and anaerobic proteins (4,19,22

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

“…Recently, Meza-Basso et al (17) observed similar changes during low temperature treatment of winter rapeseed seedlings. The 23 kD subunit of ribulose 1,5-bisP carboxylase was found to be reduced by cold treatment ( 17).…”

“…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.…”

Modifications to Thylakoid Composition during Development of Maize Leaves at Low Growth Temperatures

“…However, chilling maize leaves at low light results in a large decrease in the quantum yield of carbon assimilation, the basis of which is as yet unresolved, in the absence of any damage to PSII (25). Recently, severe impairment of the synthesis of some chloroplast proteins has been observed at chilling temperatures in rice ( 11) and rape (20), and on rewarming after chilling in tomato (5). Also, the accumulation of a 3 l-kD polypeptide in the thylakoids has been observed on chilling maize leaves; this polypeptide is considered to be an unprocessed precursor of the 29-kD apoprotein of the Chl-protein CP29 and its appearance is probably associated with an inhibition of its processing peptidase at low temperatures ( 12).…”

The Use of Callus Cultures for Searching Proteins Associated with Increased Freezing Tolerance During Cold Acclimation in Lonicera caerulea.

“…Many investigations have tried to elucidate the physiological and molecular events that take place during cold-acclimation (Levitt, 1980;Sakai and Larcher, 1987), and one approach has been to seek out proteins involved in increasing the freezing tolerance of the cells. It has been reported that low, nonfreezing temperatures induce the exclusive accumulation of some proteins in leaves and stems in plants such as Arabidopsis thaliana (Kurkela and Franck, 1990;Nordin et al, 1991;Gilmour et al, 1992), alfalfa (Mohapatra et al,1989), spinach , Brassica (Meza-Basso et al, 1986;Weretilnyk et al, 1993) and wheat (Perras and Sarhan, 1989). In woody plants grown in fields, the proteins that showed a specific increase in response to chilling treatment were found in the floral buds of blueberry (Muthalif and Rowland, 1994) and in the bark and xylem tissues of peach (Arora et al, 1992).…”