Guard cell malic acid metabolism during stomatal movements


THE mechanism by which stomata open and close has long been a puzzle, but only now are we beginning to make major advances in our understanding of their metabolism. It has been concluded that guard cells can fix CO2 and incorporate it into starch1–3. It has been shown that the bulk of, if not all, the CO2 fixed by guard cells is converted to oxaloacetic acid (OAA) by phosphoenolpyruvate carboxylase and the OAA, in turn, is reduced to malic acid3,4. Some amination of OAA producing aspartate has also been detected4. Although there is indirect evidence suggesting that aspartate and/or malate can provide carbon for starch synthesis in the guard cells4 direct evidence for this is lacking. We have investigated some characteristics of guard cell CO2 fixation which directly results in organic acid formation and we also have direct evidence that malic acid is a precursor of starch formation.

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  1. 1

    Shaw, M. & Maclachlan, G. A. Can. J. Bot. 32, 784–794 (1954).

    CAS  Article  Google Scholar 

  2. 2

    Nishida, K. Physiologia Pl. 16, 281–298 (1963).

    CAS  Article  Google Scholar 

  3. 3

    Willmer, C. M., Pallas, J. E., Jr & Black, C. C., Jr. Pl. Physiol. 52, 448–452 (1973).

    CAS  Article  Google Scholar 

  4. 4

    Willmer, C. M. & Dittrich, P. Planta 117, 123–132 (1974).

    CAS  Article  Google Scholar 

  5. 5

    Allaway, W. G. Planta 110, 63–70 (1973).

    CAS  Article  Google Scholar 

  6. 6

    Meidner, H. & Mansfield, T. A. Physiology of Stomata 141–145 (McGraw-Hill, New York, 1968).

    Google Scholar 

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WILLMER, C., RUTTER, J. Guard cell malic acid metabolism during stomatal movements. Nature 269, 327–328 (1977).

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