Journal
NEW PHYTOLOGIST
Volume 187, Issue 1, Pages 145-158Publisher
WILEY-BLACKWELL
DOI: 10.1111/j.1469-8137.2010.03241.x
Keywords
Beta vulgaris (sugar beet); CO2 mesophyll conductance; CO2 stomatal conductance; photosynthesis limitations; zinc (Zn) excess
Categories
Funding
- Spanish Ministry of Science and Innovation [AGL2007-61948, BFU2008-01072/BFI]
- I3P-CSIC
Ask authors/readers for more resources
P>The effects of zinc (Zn) toxicity on photosynthesis and respiration were investigated in sugar beet (Beta vulgaris) plants grown hydroponically with 1.2, 100 and 300 mu M Zn. A photosynthesis limitation analysis was used to assess the stomatal, mesophyll, photochemical and biochemical contributions to the reduced photosynthesis observed under Zn toxicity. The main limitation to photosynthesis was attributable to stomata, with stomatal conductances decreasing by 76% under Zn excess and stomata being unable to respond to physiological and chemical stimuli. The effects of excess Zn on photochemistry were minor. Scanning electron microscopy showed morphological changes in stomata and mesophyll tissue. Stomatal size and density were smaller, and stomatal slits were sealed in plants grown under high Zn. Moreover, the mesophyll conductance to CO2 decreased by 48% under Zn excess, despite a marked increase in carbonic anhydrase activity. Respiration, including that through both cytochrome and alternative pathways, was doubled by high Zn. It can be concluded that, in sugar beet plants grown in the presence of excess Zn, photosynthesis is impaired due to a depletion of CO2 at the Rubisco carboxylation site, as a consequence of major decreases in stomatal and mesophyll conductances to CO2.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available