Beltrán et al. 2013 (Article) Guzmania, Werauhia

Juvenile tank-bromeliads lacking tanks: do they engagein CAM photosynthesis?

Author(s):—J. Beltrán, E. Lasso, S. Madriñán, A. Virgo & K. Winter

Corresponding email:—winterk@si.edu

Publication:—Photosynthetica 51 (1): 55-62. (2013) — DOI

Abstract:—In the epiphytic tillandsioids, Guzmania monostachia, Werauhia sanguinolenta , and Guzmania lingulata (Bromeliaceae), juvenile plants exhibit an atmospheric habit, whereas in adult plants the leaf bases overlap and form water-holding tanks.CO 2 gas-exchange measurements of the whole, intact plants and 13 C values of mature leaves demonstrated that C 3 photosynthesis was the principal pathway of CO 2 assimilation in juveniles and adults of all three species. Nonetheless,irrespective of plant size, all three species were able to display features of facultative CAM when exposed to droughtstress. The capacity for CAM was the greatest in G. monostachia , allowing drought-stressed juvenile and adult plants toexhibit net CO2 uptake at night. CAM expression was markedly lower in W. sanguinolenta , and minimal in G . lingulata .In both species, low-level CAM merely sufficed to reduce nocturnal respiratory net loss of CO2. 13 C values weregenerally less negative in juveniles than in adult plants, probably indicating increased diffusional limitation of CO 2 uptake in juveniles.

Keywords:—bromeliads; CO 2 exchange; carbon isotope discrimination; crassulacean acid metabolism; drought stress; Guzmania ; heteroblasty; photosynthesis; Werauhia