Heat Shock Proteins in Germinating Pollen of Nicotiana tabacum Before and After Heat Shock

Abstract

The common response of cells to (heat) stress is an increased synthesis of a specific group of proteins known as HSP's, concomitant with a reduction in the synthesis of the normal proteins. HSP's are believed to play a role in the survival of the organism to (heat) stress. The protein synthesis in pollen of Nicotiana tabacum, incuba- ted in vitro, is affected by a heat shock of 30 min applied after germination. The production of HSP's could be established but a concomitant change in the synthesis of the normal proteins was not present. Pollen of tobacco not only synthesizes high molecular weight HSP's but also low molecular weight HSP's. Some HSP's are already present before heat shock, indicating that transcriptionally control- led synthesis of HSP-mRNA's also occurs during normal pollen tube growth. The HSP's in pollen of tobacco are compared with the set of classical HSP's normally found in other cells. INTRODUCTION