Withstanding heat waves: proteomic analysis of adaptive thermotolerance in Eucalyptus grandis seedlings

Heat wave events have been implicated in an increasing number of large scale die-off events in eucalypt-dominated forest throughout Australia. Being sedentary, plants in part rely on the expression of a specific set of proteins for heat acclimation and survival. However, the specific patterns of protein expression that underlie variability in important ecological traits like thermotolerance are rarely investigated in native plant species. This study tested the capacity of six provenances of Eucalyptus grandis (Flooded Gum) arrayed along a strong temperature gradient to respond to experimental manipulations of heat shock. Recently sequenced, E. grandis is a dominant species in forests along the east coast of Australia and a key species in forestry plantings. A comparative proteomic approach was used to characterise types and abundances of proteins involved in the heat shock response between seedlings grown from different provenances. We focused on seedlings as they are most vulnerable to intense heat conditions at the soil surface and to have limited access to soil moisture due to shallow root systems. Synthesis: Seedlings from southern provenances that experience more frequent heat stress, demonstrated higher levels of acquired thermotolerance and may have greater adaptive capacity to cope with increased heat waves under climate change.