0000000000522762
AUTHOR
Tammy L. Sage
Gisekia(Gisekiaceae): Phylogenetic relationships, biogeography, and ecophysiology of a poorly known C4lineage in the Caryophyllales
• Premise of the study: Gisekiaceae are a monogeneric family of the core Caryophyllales distributed in arid regions of Africa and Asia. The only widespread species of the genus, Gisekia pharnaceoides, performs C4 photosynthesis based on CO2 compensation point measurements. This study investigates the C4 syndrome and its evolution in Gisekia. The infrageneric relationships, distribution and bioclimatic preferences of Gisekia are also investigated.• Methods: Leaf gas exchange characteristics, activity of Rubisco and major C4 cycle enzymes, and ultrastructural characteristics of mesophyll and bundle sheath cells are studied for Gisekia pharnaceoides. δ13C values and leaf anatomy are analyzed f…
Variation in leaf anatomical traits relates to the evolution of C4 photosynthesis in Tribuloideae (Zygophyllaceae)
Abstract Tribuloideae (Zygophyllaceae, Zygophyllales) is a warm-climate clade of mostly creeping herbs with an uncertain number of C4 species from at least two genera, raising the possibility of multiple C4 origins within this lineage. To delineate C3 and C4 distributions within Tribuloideae, we conducted a phylogenetic analysis using four genetic markers from 78 accessions of Tribuloideae. δ13C values from 68 Tribuloideae members detected 42 C4 species in the genera Kallstroemia, Tribulopis and Tribulus, and no C4 in Balanites, Neoluederitzia, and Sisyndite. All Kallstroemia are C4, while Tribulopis and Tribulus include C3 species. Two independent C4 origins are supported, one in Tribulus …