Temperature-stress response in maize: a comparison of several cultivars

Abstract

The protein synthetic response to a heat (28–41 °C) and a cold (28–4 °C) shock was studied in seedlings from 10 cultivars of maize with varying levels of cold tolerance. This response was compared by fluorography of one-dimensional polyacrylamide gels and immunoblot analysis. We utilized polyclonal antibodies against the 18 000 dalton (Da) heat-shock protein and the 73 000–89 000 Da heat-shock protein complex from Oh43 maize seedlings to ascertain antigenic similarity of these polypeptides. The heat-shock response varied in the numbers and relative molecular masses of the heat-shock proteins. Only three polypeptides appeared to be conserved across cultivars: a 93 000, 71 000, and 18 000 Da polypeptide. The cold-shock response varied from none to a dramatically altered pattern in a few cultivars. Thus, the heat- and cold-shock responses in these cultivars of corn differ in the types of polypeptides that are induced. All cultivars showed varying degrees of cross-reactivity when probed with the anti 18 000 Da heat-shock protein antibody. The inbred lines appeared to respond more to a cold shock than the hybrid lines but there was little relationship between the cold tolerance and the induction of a cold-shock response. Two of the cultivars demonstrated unique binding to a higher molecular weight polypeptide under control (28 °C) conditions. These data suggest that within species variation in both number and relative molecular weight of thermal stress polypeptides (heat and cold) is a function of genotype.Key words: heat shock, cold shock, cold tolerance, maize, gene expression.