0000000000022390
AUTHOR
Rowan F. 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…
Phylogeny of Sesuvioideae (Aizoaceae) – Biogeography, leaf anatomy and the evolution of C4 photosynthesis
Abstract Sesuvioideae (Aizoaceae) form a small subfamily of drought-tolerant plants exhibiting leaf succulence, halophytic ecology, and the C4 photosynthetic pathway. Sesuvioideae are sister to the species-rich subfamilies Ruschioideae, Mesembryanthemoideae and Aizooideae that contain many CAM lineages. This close relationship of CAM and C4 taxa identifies the Sesuvioideae as an important clade to address hypotheses of photosynthetic pathway evolution. This study presents a molecular phylogeny of Sesuvioideae based on five markers (atpB-rbcL spacer, rps16 intron, trnL-trnF spacer, petB-petD spacer, ITS) and 51 accessions representing all genera and 37 species. We determined carbon isotope d…
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 …