Heat shock protein 101 plays a crucial role in thermotolerance in arabidopsis

Plants are sessile organisms, and their ability to adapt to stress is cruci al for survival in natural environments. Many observations suggest a relati onship between stress tolerance and heat shock proteins (HSPs) in plants, b ut the roles of individual HSPs are poorly characterized. We report that tr ansgenic Arabidopsis plants expressing less than usual amounts of HSP101, a result of either antisense inhibition or cosuppression, grew at normal rat es but had a severely diminished capacity to acquire heat tolerance after m ild conditioning pretreatments. The naturally high tolerance of germinating seeds, which express HSP101 as a result of developmental regulation, was a lso profoundly decreased. Conversely, plants constitutively expressing HSP1 01 tolerated sudden shifts to extreme temperatures better than did vector c ontrols. We conclude that HSP101 plays a pivotal role in heat tolerance in Arabidopsis. Given the high evolutionary conservation of this protein and t he fact that altering HSP101 expression had no detrimental effects on norma l growth or development, one should be able to manipulate the stress tolera nce of other plants by altering the expression of this protein.