Early and late heat shock proteins in wheats and other cereal species.

Coleoptiles and roots of 3-day-old seedlings from five cereal species (Triticum aestivum L., T. durum Desf., Hordeum vulgare L., Secale cereale L., and Triticale) respond to heat shock at 40 degrees C by synthesizing a new set of 13 strong bands (as revealed by one-dimensional sodium dodecyl sulfate gel electrophoresis) as well as some 20 degrees C proteins. Heat shock proteins (HSPs) belong to three different size groups: high molecular mass HSPs in the 103 to 70 kilodalton range, intermediate molecular mass HSPs in the 62 to 32 kilodalton range, and low molecular mass HSPs about 17 to 16 kilodalton in size. At the beginning of the heat shock coleoptiles show a reduced ability to synthesize intermediate molecular mass HSPs but after 4 hours at 40 degrees C they exhibit fully developed HSP patterns identical to that found in roots. Synthesis of early HSPs declines after 7 hours of treatment followed by the appearance of a new set of 12 protein bands (late HSPs) in the ranges 99 to 83, 69 to 35, and 15 to 14 kilodaltons. After 12 hours at 40 degrees C, three other late HSPs of 89, 45, and 38 kilodalton are induced. The induction of late HSPs after 7 hours at 40 degrees C appears to be associated with an enhancement of radioactive methionine incorporation into proteins.