Previous reports on temperature stress responses in maize examined the alterations in the pattern of polypeptide synthesis in tissues of 5- to 6-day-old maize seedlings (Baszczynski et al., 1982, 1983). A similar response has now been observed in leaf tissue from entire plants at the 6-8 leaf stage subjected to a brief shift in growing temperature.
Seeds (Oh43) were germinated in flats. Seedlings were transplanted to large pots and grown outside. Leaf samples were taken and labeled at 25 C (100 uCi/ml, 35S-methionine, 2 h). The plants were then placed in an incubator at 45 C. After one hour, leaf samples were labeled at 45 C (100 uCi/ml, 35S-methionine, 2 h). Protein extracts from these leaf samples were subjected to two-dimensional IEF-SDS PAGE followed by fluorography.
Examination of the patterns of polypeptide synthesis revealed enhanced synthesis of seven classes of polypeptides after temperature shift: 108, 89, 84, 76, 73, 23, 18 kilodaltons (kD). Enhanced synthesis of six classes of polypeptides (excluding the 23 kD class) was revealed in plumules and radicles of 5- to 6-day-old seedlings subjected to a one-hour temperature shift (27 C to 41 C) (Baszczynski et al., 1982). Enhanced synthesis of the 23 kD polypeptide class may represent a leaf specific response or a response specific to the temperature shift used in this experiment. Work by others in our laboratory has demonstrated enhanced synthesis of a polypeptide of similar size (23 kD) after a temperature shift from 30 C to 42 C in plumules of 5-day-old maize seedlings (see previous contributions in this Newsletter).
Carol A. Rees-Farrell and D. B. Walden
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