CAM variations in the leaf-succulent Delosperma tradescantioides (Mesembryanthemaceae), native to southern Africa

Herppich, Werner B.; Midgley, Guy F.; Willert, D. J. von; Veste, Maik

doi:10.1034/j.1399-3054.1996.980308.x

Cited by 1 publication

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“…This has been demonstrated in other storage succulents via intermediate isotopic values (e.g. Mooney et al , 1977 ; Rundel et al , 1999 ) and by more direct measures of CAM activity ( Herppich et al , 1996 ; Veste et al , 2001 ). CAM-idling has been shown to be important for enduring drought and, subsequent to stomatal closure, the ability to capture and release respiratory CO 2 allows continued light reaction activity that protects the photosynthetic apparatus from photoinhibition ( Ting, 1985 ; Adams et al , 1987 ; Griffiths et al , 1989 ; Herrera, 2009 ).…”

Section: Introductionmentioning

confidence: 78%

“…Such rapid gas exchange responses to water inputs have been demonstrated in various leaf succulents including Ruschia caroli (Aizoaceae; Midgley and van der Heyden, 1999 ), Mesembryanthemum pellitum (Aizoaceae), and Othonna optima (Asteraceae; Eller et al , 1993 ). The maintenance of photochemical integrity may be aided by CAM-idling, or drought-induced low-level CAM, which has been demonstrated in D. tradescantioides (Aizoaceae; Herppich et al , 1996 ). CAM-idling does not contribute to overall carbon assimilation and hence does not result in discernible CAM δ 13 C signal ( Winter and Holtum, 2002 ).…”

Section: Discussionmentioning

confidence: 99%

“…For example, Delosperma tradescantioides can rapidly switch between C 3 and CAM (Herppich et al , 1996). This has been demonstrated in other storage succulents via intermediate isotopic values (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…This does not imply that species that develop leaf succulence via a central achlorophyllous hydrenchyma are precluded from having CAM or being facultatively CAM. For example, Delosperma tradescantioides can rapidly switch between C 3 and CAM ( Herppich et al , 1996 ). This has been demonstrated in other storage succulents via intermediate isotopic values (e.g.…”

Section: Introductionmentioning

confidence: 99%

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How succulent leaves of Aizoaceae avoid mesophyll conductance limitations of photosynthesis and survive drought

Ripley

Abraham

Klak

et al. 2013

Journal of Experimental Botany

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In several taxa, increasing leaf succulence has been associated with decreasing mesophyll conductance (g M) and an increasing dependence on Crassulacean acid metabolism (CAM). However, in succulent Aizoaceae, the photosynthetic tissues are adjacent to the leaf surfaces with an internal achlorophyllous hydrenchyma. It was hypothesized that this arrangement increases g M, obviating a strong dependence on CAM, while the hydrenchyma stores water and nutrients, both of which would only be sporadically available in highly episodic environments. These predictions were tested with species from the Aizoaceae with a 5-fold variation in leaf succulence. It was shown that g M values, derived from the response of photosynthesis to intercellular CO2 concentration (A:C i), were independent of succulence, and that foliar photosynthate δ13C values were typical of C3, but not CAM photosynthesis. Under water stress, the degree of leaf succulence was positively correlated with an increasing ability to buffer photosynthetic capacity over several hours and to maintain light reaction integrity over several days. This was associated with decreased rates of water loss, rather than tolerance of lower leaf water contents. Additionally, the hydrenchyma contained ~26% of the leaf nitrogen content, possibly providing a nutrient reservoir. Thus the intermittent use of C3 photosynthesis interspersed with periods of no positive carbon assimilation is an alternative strategy to CAM for succulent taxa (Crassulaceae and Aizoaceae) which occur sympatrically in the Cape Floristic Region of South Africa.

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