HEAT-SHOCK RESPONSE OF PINUS AND PICEA SEEDLINGS

The effect of a short period of elevated temperature, or heat shock, o n protein synthesis was investigated in 2-day-old seedlings of jack pi ne (Pinus banksiana Lamb.), loblolly pine (P. taeda L.), lodgepole pin e (P. contorta Dougl.), black spruce (Picea mariana (Mill.) BSP), and white spruce (P. glauca (Moench) Voss). In all species, heat shock led to increased [S-35]methionine incorporation into heat-shock proteins (hsp's) with molecular masses of 83 and 72 kDa. Heat shock also induce d synthesis of several low molecular weight proteins that were absent from control seedlings. The low molecular weight hsp's produced by pin e seedlings had molecular masses of 27, 24.6, 20.5 and 17.5 kDa, where as those produced by spruce seedlings had molecular masses of 27.2, 19 .8, 18.4, 17.2 and 16.0 kDa. All of the low molecular weight hsp's sho wed isoelectric variants. Heat shock led to increased [S-35]methionine incorporation into a group of low molecular weight hsp's that were al so present in control seedlings.