, Volume 35, Issue 2, pp 273–277

Diel Acid Fluctuations in C4 Amphibious Grasses

  • J.E. Keeley

DOI: 10.1023/A:1006927327013

Cite this article as:
Keeley, J. Photosynthetica (1998) 35: 273. doi:10.1023/A:1006927327013


Orcuttieae is a small tribe of C4 grasses endemic to seasonal pools in the southwestern U.S., comprising the basal genus Neostapfia, Tuctoria, and the most derived group, Orcuttia. Growth is initiated underwater, and when pools dry, species undergo a metamorphosis replacing aquatic foliage with terrestrial foliage. O. californica and O. viscida exhibit CAM-like diel fluctuations in acidity in the aquatic foliage. Pulse-chase studies showed that although CO2 was fixed into malic acid in the dark, an overnight chase in the dark revealed that most label was not retained in organic acids, indicating a role other than CAM. Terrestrial foliage exhibited a very different diel fluctuation; acids accumulated during the day, and diminished overnight. Malic acid predominated and was secreted on the surface of the leaf in a manner similar to another arid land species. This terrestrial daytime acid accumulation may not be related to photosynthetic pathway but may play an anti-herbivore function. No acid fluctuations were observed in either N. colusana or T. greenei.

aquatic and terrestrial leaves 14C labelling chlorophyll malic acid Neostapfia colusana Orcuttia californica and O. viscida titratable acidity Tuctoria greenie 

Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • J.E. Keeley
    • 1
  1. 1.Department of BiologyOccidental CollegeLos AngelesU.S.A

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