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

ABSTRACT: 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 (? = 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 (? decreased to the ? thresholds) and while those threshold ? were maintained. Stomatal conductance (g(s)) and net photosynthesis (A) decreased with decreasing midday leaf water potential (?(leaf)). Leaf ABA concentration increased with decreasing midday ?(leaf) and was negatively correlated with g(s) (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 (? = 0.10 m(3)•m(-3)), suggesting a decrease in ABA catabolism under severe drought. Expression of phospholipase D? (PLD?), involved in regulating stomatal responses to ABA, was enhanced under drought during the drying phase, but there was no relationship between PLD? expression and midday ?(leaf) after the ? 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.

SUBMITTER: Kim J

PROVIDER: S-EPMC3504489 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

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

Kim Jongyun J Malladi Anish A van Iersel Marc W MW

Journal of experimental botany 20121017 18

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 wer ...[more]

PMID: 23077204

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Project description:Tomato is a major crop in the Mediterranean basin, where the cultivation in the open field is often vulnerable to drought. In order to adapt and survive to naturally occurring cycles of drought stress and recovery, plants employ a coordinated array of physiological, biochemical, and molecular responses. Transcriptomic studies on tomato responses to drought and subsequent recovery are few in number. As the search for novel traits to improve the genetic tolerance to drought increases, a better understanding of these responses is required. To address this need we designed a study in which we induced two cycles of prolonged drought stress and a single recovery by rewatering in tomato. In order to dissect the complexity of plant responses to drought, we analyzed the physiological responses (stomatal conductance, CO2 assimilation, and chlorophyll fluorescence), abscisic acid (ABA), and proline contents. In addition to the physiological and metabolite assays, we generated transcriptomes for multiple points during the stress and recovery cycles. Cluster analysis of differentially expressed genes (DEGs) between the conditions has revealed potential novel components in stress response. The observed reduction in leaf gas exchanges and efficiency of the photosystem PSII was concomitant with a general down-regulation of genes belonging to the photosynthesis, light harvesting, and photosystem I and II category induced by drought stress. Gene ontology (GO) categories such as cell proliferation and cell cycle were also significantly enriched in the down-regulated fraction of genes upon drought stress, which may contribute to explain the observed growth reduction. Several histone variants were also repressed during drought stress, indicating that chromatin associated processes are also affected by drought. As expected, ABA accumulated after prolonged water deficit, driving the observed enrichment of stress related GOs in the up-regulated gene fractions, which included transcripts putatively involved in stomatal movements. This transcriptomic study has yielded promising candidate genes that merit further functional studies to confirm their involvement in drought tolerance and recovery. Together, our results contribute to a better understanding of the coordinated responses taking place under drought stress and recovery in adult plants of tomato.

Dataset Information

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

Publications

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

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