Sulfate Transport Processes Under Drought Stress: Interaction with Mycorrhization and Elevated pCO2 in Young Pedunculate Oak (Quercus robur L.) Trees

Seegmüller, S.; Rennenberg, Heinz

doi:10.1007/978-94-007-4450-9_31

Cited by 1 publication

(1 citation statement)

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“…Malcheska et al (2013) suggested that sulfate in the xylem sap can originate from sulfate uptake by roots or by sulfate release from xylem parenchyma and pith ray cells of the wood. Lateral roots of Quercus robur seedlings, however, showed sulfate uptake rates being independent of predrawn shoot water potential, but xylem loading strongly declined with decreasing leaf water potential (Seegmüller and Rennenberg, 2012). This effect should not increase (as found in this study), but instead decrease sulfate in the xylem sap upon drought.…”

Section: Discussionsupporting

confidence: 55%

Drought-Enhanced Xylem Sap Sulfate Closes Stomata by Affecting ALMT12 and Guard Cell ABA Synthesis

Ahmad²,

et al. 2017

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Water limitation of plants causes stomatal closure to prevent water loss by transpiration. For this purpose, progressing soil water deficit is communicated from roots to shoots. Abscisic acid (ABA) is the key signal in stress-induced stomatal closure, but ABA as an early xylem-delivered signal is still a matter of debate. In this study, poplar plants () were exposed to water stress to investigate xylem sap sulfate and ABA, stomatal conductance, and sulfate transporter () expression. In addition, stomatal behavior and expression of ABA receptors, drought-responsive genes, transcription factors, and were studied after feeding sulfate and ABA to detached poplar leaves and epidermal peels of Arabidopsis (). The results show that increased xylem sap sulfate is achieved upon drought by reduced xylem unloading by PtaSULTR3;3a and PtaSULTR1;1, and by enhanced loading from parenchyma cells into the xylem via PtaALMT3b. Sulfate application caused stomatal closure in excised leaves and peeled epidermis. In the loss of sulfate-channel function mutant, At, sulfate-triggered stomatal closure was impaired. The QUAC1/ALMT12 anion channel heterologous expressed in oocytes was gated open by extracellular sulfate. Sulfate up-regulated the expression of , a key step of ABA synthesis, in guard cells. In conclusion, xylem-derived sulfate seems to be a chemical signal of drought that induces stomatal closure via QUAC1/ALMT12 and/or guard cell ABA synthesis.

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Section: Discussionsupporting

confidence: 55%