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SUMMARY:Effect of elevated inorganic carbon on cytosolic anion homeostasis
 : nitrate efflux in seagrasses - Prof.  Lourdes Rubio\, University of Mala
 ga
DTSTART:20191219T130000Z
DTEND:20191219T140000Z
UID:TALK136114@talks.cam.ac.uk
CONTACT:81370
DESCRIPTION:Seagrasses are the only group of flowering plants to colonize 
 the sea. These plants occupy a relatively stable environment\, characteris
 ed by high salinity (0.5 M NaCl)\, alkaline pH (8.2) and low availability 
 of essential nutrients such as nitrate or phosphate (below 10 µM). Furthe
 rmore\, one of the major challenges that face marine angiosperms is the ac
 quisition of dissolved inorganic carbon for photosynthesis. Those conditio
 ns suggest that these plants have developed special physiological mechanis
 ms for adaptation to the marine environment\, which should be firmly fixed
  in their genome. As vascular plants\, these species conserve the proton A
 TPase as the primary pump to energize plasma membrane. Using electrophysio
 logy\, mainly ion-selective microelectrodes\, we have shown that the proto
 n economy is used to maintain cytosolic sodium homeostasis and to drive th
 e direct uptake of bicarbonate in Posidonia oceanica\, a Mediterranean sea
 grass endemism. However\, as we also reported for Zostera marina\, sodium 
 dependent mechanisms are used for the high-affinity uptake of nitrate or P
 i. In the context of climate change\, seagrasses face two major consequenc
 es\; the rise of dissolved inorganic carbon species (CO2 and bicarbonate) 
 and seawater acidification. Most seagrasses show non-saturated C3 photosyn
 thesis and are able to use bicarbonate as an inorganic carbon source. In t
 he case of P. oceanica\, bicarbonate use has an important side effect on c
 ytosolic chloride\, probably by the opening the S-type anion channels\, wh
 ich also mediate nitrate efflux. Consequently\, bicarbonate enrichment of 
 natural seawater also evokes the on-going decrease of cytosolic nitrate in
  P. oceanica mesophyll leaf cells. Thus\, the chronic diminution of cytoso
 lic nitrate could impair nitrogen assimilation and would contribute to the
  N biomass dilution expected under elevated inorganic carbon. 
LOCATION:Tom ap Rees\, Department of Plant Sciences
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