Dennis Konnerup1, Louis Moir-Barnetson2, Ole Pedersen3, Erik J Veneklaas2, Timothy D Colmer2. 1. School of Plant Biology and Institute of Advances Studies, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia and Freshwater Biological Laboratory, Institute of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark dennis.konnerup@uwa.edu.au. 2. School of Plant Biology and Institute of Advances Studies, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia and Freshwater Biological Laboratory, Institute of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark. 3. School of Plant Biology and Institute of Advances Studies, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia and Freshwater Biological Laboratory, Institute of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark School of Plant Biology and Institute of Advances Studies, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia and Freshwater Biological Laboratory, Institute of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark School of Plant Biology and Institute of Advances Studies, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia and Freshwater Biological Laboratory, Institute of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark.
Abstract
BACKGROUND AND AIMS: Many stem-succulent halophytes experience regular or episodic flooding events, which may compromise gas exchange and reduce survival rates. This study assesses submergence tolerance, gas exchange and tissue oxygen (O2) status of two stem-succulent halophytes with different stem diameters and from different elevations of an inland marsh. METHODS: Responses to complete submergence in terms of stem internal O2 dynamics, photosynthesis and respiration were studied for the two halophytic stem-succulents Tecticornia auriculata and T. medusa. Plants were submerged in a glasshouse experiment for 3, 6 and 12 d and O2 levels within stems were measured with microelectrodes. Photosynthesis by stems in air after de-submergence was also measured. KEY RESULTS: Tecticornia medusa showed 100 % survival in all submergence durations whereas T. auriculata did not survive longer than 6 d of submergence. O2 profiles and time traces showed that when submerged in water at air-equilibrium, the thicker stems of T. medusa were severely hypoxic (close to anoxic) when in darkness, whereas the smaller diameter stems of T. auriculata were moderately hypoxic. During light periods, underwater photosynthesis increased the internal O2 concentrations in the succulent stems of both species. Stems of T. auriculata temporally retained a gas film when first submerged, whereas T. medusa did not. The lower O2 in T. medusa than in T. auriculata when submerged in darkness was largely attributed to a less permeable epidermis. The submergence sensitivity of T. auriculata was associated with swelling and rupturing of the succulent stem tissues, which did not occur in T. medusa. CONCLUSIONS: The higher submergence tolerance of T. medusa was not associated with better internal aeration of stems. Rather, this species has poor internal aeration of the succulent stems due to its less permeable epidermis; the low epidermal permeability might be related to resistance to swelling of succulent stem tissues when submerged.
BACKGROUND AND AIMS: Many stem-succulent halophytes experience regular or episodic flooding events, which may compromise gas exchange and reduce survival rates. This study assesses submergence tolerance, gas exchange and tissue oxygen (O2) status of two stem-succulent halophytes with different stem diameters and from different elevations of an inland marsh. METHODS: Responses to complete submergence in terms of stem internal O2 dynamics, photosynthesis and respiration were studied for the two halophytic stem-succulents Tecticornia auriculata and T. medusa. Plants were submerged in a glasshouse experiment for 3, 6 and 12 d and O2 levels within stems were measured with microelectrodes. Photosynthesis by stems in air after de-submergence was also measured. KEY RESULTS:Tecticornia medusa showed 100 % survival in all submergence durations whereas T. auriculata did not survive longer than 6 d of submergence. O2 profiles and time traces showed that when submerged in water at air-equilibrium, the thicker stems of T. medusa were severely hypoxic (close to anoxic) when in darkness, whereas the smaller diameter stems of T. auriculata were moderately hypoxic. During light periods, underwater photosynthesis increased the internal O2 concentrations in the succulent stems of both species. Stems of T. auriculata temporally retained a gas film when first submerged, whereas T. medusa did not. The lower O2 in T. medusa than in T. auriculata when submerged in darkness was largely attributed to a less permeable epidermis. The submergence sensitivity of T. auriculata was associated with swelling and rupturing of the succulent stem tissues, which did not occur in T. medusa. CONCLUSIONS: The higher submergence tolerance of T. medusa was not associated with better internal aeration of stems. Rather, this species has poor internal aeration of the succulent stems due to its less permeable epidermis; the low epidermal permeability might be related to resistance to swelling of succulent stem tissues when submerged.
Authors: Ole Pedersen; Sarah Meghan Rich; Cristina Pulido; Gregory Robert Cawthray; Timothy David Colmer Journal: New Phytol Date: 2010-11-09 Impact factor: 10.151
Authors: Pieter Verboven; Ole Pedersen; Quang Tri Ho; Bart M Nicolai; Timothy D Colmer Journal: Plant Cell Environ Date: 2014-03-20 Impact factor: 7.228