Depressed heat shock responses in low vigor seed lots of Triticum Aesitivum L. during early germination

The authors are testing the hypothesis that heat shock proteins (hsp's) are important in conferring seed vigor by promoting survival of environmental stresses at early times of inhibition. They are comparing the production of seven hsp's produced in embryos isolated from high (N83 and W83) and low (N80 and W80) vigor seedlots of wheat. Seed vigor was determined by the accelerated aging test. Following 1.5 or 12 hrs of inhibition, 6 embryos from each lot were simultaneously labeled with 35S Methionine and subjected to a 420C heat shock for 90 min, then homogenized in a solubilizing buffer, boiled, and cleared by centrifugation. The activity of the samples was determined and proteins from aliquots of equal activity were separated by SDS-PAGE. Labeled proteins were then detected and quantified by autoradiography and densitometry, respectively. Relative heat shock responses (rhsr), defined as the total area of hsp's 97, 94, 83, 70, 68, and a 17-18 Kd doublet divided by the total area detected on a given lane, were compared between high and low vigor lots for both inhibition times. At 1.5 hr. of inhibition, N80 showed a 22.8% decline in rhsr compared to N83, and W80 showed a decline of 22.9% of rhsr compared to W83. At 12 hrs of inhibition, N80 had a 13.8% lower rhsr than N83 and W80 had a rhsr 15.7% lower than that of W83. These data represent 2-4 replications. The results support the hypothesis that hsl's play an important role in seed vigor