Physiological and molecular responses to drought in Petunia: The importance of stress severity

Jongyun Kim, Anish Malladi, Marc W. Van Iersel

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


Plant responses to drought stress vary depending on the severity of stress and the stage of drought progression. To improve the understanding of such responses, the leaf physiology, abscisic acid (ABA) concentration, and expression of genes associated with ABA metabolism and signalling were investigated in Petunia × hybrida. Plants were exposed to different specific substrate water contents (θ = 0.10, 0.20, 0.30, or 0.40 m 3·m-3) to induce varying levels of drought stress. Plant responses were investigated both during the drying period (θ decreased to the θ thresholds) and while those threshold θ were maintained. Stomatal conductance (gs) and net photosynthesis (A) decreased with decreasing midday leaf water potential (Ψleaf). Leaf ABA concentration increased with decreasing midday Ψleaf and was negatively correlated with gs (r = -0.92). Despite the increase in leaf ABA concentration under drought, no significant effects on the expression of ABA biosynthesis genes were observed. However, the ABA catabolism-related gene CYP707A2 was downregulated, primarily in plants under severe drought (θ = 0.10 m3·m-3), suggesting a decrease in ABA catabolism under severe drought. Expression of phospholipase Dα (PLDα), involved in regulating stomatal responses to ABA, was enhanced under drought during the drying phase, but there was no relationship between PLDα expression and midday Ψleaf after the θ thresholds had been reached. The results show that drought response of plants depends on the severity of drought stress and the phase of drought progression.

Original languageEnglish
Pages (from-to)6335-6345
Number of pages11
JournalJournal of experimental botany
Issue number18
Publication statusPublished - 2012 Nov
Externally publishedYes


  • abscisic acid
  • acclimation
  • automated irrigation
  • soil moisture sensor
  • stomatal conductance
  • substrate water content

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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