PARENT SESSION
Poster Session 1: Photosynthesis and Water Relations
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Photosynthesis in C3-C4 intermediate species of Heliotropium.

Vogan, Patrick^*,1, Sage, Rowan¹, ¹ University of Toronto, Toronto, Ontario, Canada

ABSTRACT- Anatomical traits characteristic of C₃-C₄ intermediacy have been identified in the genus Heliotropium, section Orthostachys. To date, the strength of intermediacy in terms of photosynthetic performance remains uncharacterized. Here we examine photosynthesis vs. CO₂ response of six C₃, C₃-C₄ and C₄ species in Heliotropium. C₃ and C₄ species exhibited CO₂ compensation points, initial slope values, and ¹³C values typical of their respective photosynthetic pathways. C₃-C₄ intermediate species exhibit modest reductions in the CO₂ compensation points, but initial slope and ¹³C values were otherwise typical of this pathway. We conclude that C₃-C₄ intermediacy is weakly developed in these Heliotropium species, and may be representative of a photorespiratory C₄ pump rather than true C₃-C₄ intermediacy.

Key words: C4 photosynthesis, C3-C4 intermediate, Heliotropium