Aje. Bettany, STRESS RESPONSES IN CELL-CULTURES OF LOLIUM-TEMULENTUM .2. INDUCTION OF THERMOTOLERANCE AND ASSOCIATED CHANGES IN GENE-EXPRESSION, Journal of plant physiology, 146(1-2), 1995, pp. 183-189
The induction and longevity of thermotolerance has been assessed in ce
ll cultures of Lolium temulentum and changes in gene expression associ
ated with thermotolerance determined. More than 15 minutes at 37 degre
es C was required to induce thermotolerance in these cell cultures, wi
th the highest levels of thermotolerance being obtained with a one hou
r, 37 degrees C conditioning heat shock treatment. Increasing the cond
itioning heat shock to two hours at 37 degrees C resulted in a fall in
the level of induced thermotolerance. Thermotolerance could not devel
op at 37 degrees C but required a recovery period at 25 degrees C for
more than one hour before the non-permissive heat shock. Short incubat
ions at 45 degrees C were incapable of rendering the cells thermotoler
ant, even with a recovery period. Thermotolerance persisted for at lea
st 24 hours, but had disappeared by 48 hours. Replicate cultures which
were, or were not, thermotolerant were analysed by in vitro translati
on of isolated RNAs. The major differences were a decrease in the leve
ls of a number of hsp mRNAs, and a more rapid return to pre-heat shock
levels of control mRNAs in thermotolerant cells.