The putative existence of Crassulacean acid metabolism was investigated in three succulent species of the C 4 genus Portulaca: P. grandiflora (a widely cultivated species), P. oleracea (a cosmopolitan weed), and P. mundula (found on rock outcrops throughout the southwestern United States). Patterns of diurnal conductance and C0 2 exchange, as well as diurnal tissue malic acid fluctuations, were measured in plants under well-watered and drought-stressed conditions. Net C0 2 uptake in both treatments occurred only during the day, although small amounts of nighttime C0 2 uptake occurred in a few individuals. Stomatal conductances in well-watered and drought-stressed P. mundula and droughtstressed P. oleracea were higher during the night than during the day, though these higher conductances were generally not accompanied by net CO, assimilation. No significant diurnal malic acid fluctuations occurred under well-watered conditions in any species; however, under drought stress, significant diurnal malic acid fluctuations occurred in the three species. The primary source of carbon for nocturnal malic acid production is presumed to be respiratory C0 2 , as occurs in C 3 plants that undergo CAM-cycling. This study confirms past reports of CAM acid fluctuations in P. grandiflora and P. oleracea and marks the first report of CAM activity in P. mundula.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.