How the metabolism of Populus deltoides reacts to drought depends on what kind of drought it is, say Tschaplinkski and colleagues in Annals of Botany. “The differential adaptive metabolite responses in cyclic versus acute drought suggest that stress acclimation occurs via primary metabolism in response to cyclic drought, whereas expanded metabolic plasticity occurs via secondary metabolism following severe, acute drought.” Understanding how poplar reacts to drought may help breed more tolerant varieties.
The team have published their findings as two experiments. The first experiment was into cyclical drought with waterings six days apart. The second experiment, with the plants left eight days before sampling. The authors then examined the leaves of the plants to see how the drought affected metabolites.
“The nature of drought, frequency of drought and the severity of drought dictated the degree of osmotic adjustment and the nature of the organic solutes that accumulated,” said Tschaplinkski and colleagues. “Acute onset of prolonged, severe drought induced the greatest accumulation of foliar metabolites observed. Cyclic drought induced the largest responses in primary carbon metabolism (sugars and organic acids). Acute drought induced the largest responses in secondary carbon metabolism, especially conjugates of hydroxycinnamates with salicin, leading to the accumulation of populosides.”
The shift in metabolites lowers osmotic potential, increasing the dehydration tolerance of the plant.