Effects of Irradiance on Crassulacean Acid Metabolism in the Epiphyte <i>Tillandsia usneoides</i> L. (Bromeliaceae)

Martin, Craig E.; Eades, Carol A.; Pitner, Renee A.

doi:10.1104/pp.80.1.23

Cited by 38 publications

(22 citation statements)

References 13 publications

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“…Thus, the results of the current study, coupled with those of the authors' past findings, illustrate great flexibility in the concentration of chlorophyll in the H. carnosa leaves depending upon growth light levels, such that thinner shade leaves contain greater amounts of chlorophyll, even when expressed per area of leaf, than do the thicker sun leaves. Although such high chlorophyll concentrations in shade tissues are classically accompanied by lower chlorophyll a/b ratios (Boardman 1977;Björkman 1981), such is not always the case (Martin et al 1986) and was generally not true for H. carnosa in the current study. An increase in chlorophyll concentration without a concomitant decrease in chlorophyll a/b ratio during acclimation/adaptation of photosynthetic tissue to lower light levels will occur if there is an increase in the number, but not size, of the ''photosynthetic units'' (PSU) in the tissue, as increases in PSU size in response to lower light levels typically reflect, in particular, an increase in the light-harvesting portions of the photosynthetic pigment/protein complex in both photosystems.…”

Section: Resultscontrasting

confidence: 51%

“…In contrast, a less exhaustive investigation of the ecophysiology of H. carnosa plants in dense and sparse tree canopies in subtropical northeastern Taiwan provided some evidence that plants performed better in more exposed microhabitats than in shaded ones (Hsu et al 2006). The contrasting results of these studies, coupled with the widespread general interest in sun/shade adaptations in CAM epiphytes Griffiths et al 1989;Martin et al 1985Martin et al , 1986Martin et al , 1989Martin et al , 1999Winter et al 1986;Skillman and Winter 1997), as well as the potential influence of the unusual epiphytic vine growth form of H. carnosa on its ability to acclimate to sun or shade, provide ample justification for further investigation into the ability of H. carnosa to acclimate/ adapt to a wide range of light levels, such as it frequently encounters in its natural environment. Furthermore, knowledge of sun/shade adaptations in H. carnosa might provide additional information relevant to consideration of the evolution of CAM in this epiphytic vine, as well as other epiphytic CAM plants found in rain forests characterized by exceptionally high levels of precipitation.…”

Section: Introductionmentioning

confidence: 99%

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Sun/shade adaptations of the photosynthetic apparatus of Hoya carnosa, an epiphytic CAM vine, in a subtropical rain forest in northeastern Taiwan

2009

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Most past work on the ecophysiology of the Crassulacean acid metabolism (CAM) plant, Hoya carnosa, in the lab and in situ in Australia indicates that this epiphytic vine is better adapted to shaded, not exposed, locations, although a recent study of this species in Taiwan presents findings that run counter to this conclusion. Thus, photosynthetic characteristics of shaded and exposed individuals of H. carnosa were compared in situ in a subtropical rain forest in northeastern Taiwan in order to determine whether this CAM epiphyte is better adapted to the shade or the sun. Although leaves of shade plants had much greater chlorophyll concentrations than did those of sun plants, chlorophyll a/b ratios did not differ between the two groups of plants. Fluorescence measurements revealed some ability of leaves to acclimate to both shade and sun, although some evidence for photoinhibition (photoprotection) was observed in more exposed plants. Despite the latter, both exposed and shaded plants exhibited CAM, measured as diel fluctuations in leaf acidity, and CAM was more consistently found in the exposed plants. Furthermore, some evidence for more CAM at higher light availabilities was found. Overall, the results of this investigation reveal that H. carnosa in this subtropical rain forest in Taiwan exhibits adaptations to both high and low light levels, which should prove adaptive for an epiphytic vine with leaves on the same individual exposed to a wide range of exposure and shade in the host tree canopy.

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Section: Resultscontrasting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Sun/shade adaptations of the photosynthetic apparatus of Hoya carnosa, an epiphytic CAM vine, in a subtropical rain forest in northeastern Taiwan

2009

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“…The gas exchange system and chamber were identical to that used in MARTIN et al (1986). Chamber environmental conditions were 1,000-1,800 fxmol m~2s _1 PPFD (range across chamber interior) for 12 h, 25/20 C day/night air temperatures, and a constant dew point of 15.5 C. A clump of T. usneoides was fully soaked, surface-dried, then sealed into the gas exchange chamber on day 0.…”

Section: Desiccation Effects On C0 2 Exchangementioning

confidence: 99%

Unusual Water Relations in the CAM Atmospheric Epiphyte Tillandsia usneoides L. (Bromeliaceae)

Martin¹,

Schmitt²

1989

Botanical Gazette

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Past studies have reported two unusual aspects of the water relations of the atmospheric CAM epiphyte Tillandsia usneoides L. (Bromeliaceae): a drought stimulation of nocturnal C0 2 uptake, and nocturnal absorption of water vapor. Contrary to past reports, a 10-d drought did not stimulate nocturnal C0 2 uptake in this species. On the other hand, previous reports of nocturnal water vapor absorption were confirmed in situ throughout a year, although tissue hydration from this source was insufficient to offset daytime water loss. Deposition of dew on the plants was never observed in the field. It is hypothesized that the unusual nature of the water relations of T. usneoides is attributable to the interactions between two "pools" of water and the external atmosphere. The dense indumentum of trichomes obscuring the surface of this epiphyte comprises one pool and is most likely responsible for rapid hydration early in the night and dehydration early in the day. In addition, stomata control water loss from the living mesophyll cells, the second pool, for the remainder of the night. The high rates of water loss observed throughout the day when stomata are closed probably result from leakage through the trichomes.

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“…Martin et al . () evaluated a few individual Spanish moss plants from sunny and shady locations in South Carolina with different irradiance levels. Their research showed that these plants respond physiologically to various irradiance levels, suggesting that Spanish moss adjusts physiologically to the microclimates it inhabits, posing still more difficulty in generalizing physiological responses from a few populations to entire distributions.…”

Section: Discussionmentioning

confidence: 99%

“…Martin et al . (, ) assessed North Carolina Spanish moss populations with respect to the effects of irradiance on morphology and physiology, finding that Spanish moss responds to irradiance by adjusting physiology more than morphology. Studying Spanish moss populations from Newton, GA, USA, Garth () showed that, without periodic rain, Spanish moss cannot survive, even when water is supplied externally; he found that Spanish moss has optimal performance with 15 or fewer consecutive rainless days, and Martin et al .…”

Section: Methodsmentioning

confidence: 99%

The role of physiological optima in shaping the geographic distribution of Spanish moss

Barve

Martin

Brunsell

et al. 2014

Global Ecology and Biogeography

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Aim Ecological niche modelling is being widely applied to help us understand the geographic distributions of species, despite challenges regarding the estimation of fundamental niches that limit model transferability over time and space. Mechanistic models are an alternative, but they can be difficult to implement owing to the detailed knowledge that they require about the organism for full parameterization. In this paper we explore the geographic projection of physiological measurements of optimal temperature, precipitation and relative humidity requirements, as measured under controlled conditions using a climate dataset with high temporal resolution, as a case study for Spanish moss (Tillandsia usneoides), and compare scaling effects with correlative niche models calibrated in Maxent. Location The Americas. Methods We used climate data with a high temporal resolution to understand how often and where populations of Spanish moss occur under optimal and suboptimal conditions with respect to different environmental variables across their geographic range. We used weather station data for the United States with higher spatial resolution to provide a finer‐grained view. We also developed an ecological niche model to show how averaged climate data can present inaccurate views of physiological thresholds for the species. Results Few populations of Spanish moss are located at sites that present suboptimal conditions for more than two environmental parameters. The northern distributional limit of Spanish moss is set by minimum temperature requirements, whereas maximum temperatures are less limiting. However, when the same occurrences are analysed with respect to averaged climate data, 95% of populations appear to fall within the optimal physiological intervals. Main conclusions Our analyses revealed that most populations of Spanish moss do not experience optimal ecophysiological conditions for all environmental variables, even over long time‐scales. Physiological data may be of limited utility in delimiting suitable areas for populations of species, but they offer unique perspectives on the causes of range limitation.

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Effects of Irradiance on Crassulacean Acid Metabolism in the Epiphyte Tillandsia usneoides L. (Bromeliaceae)

Cited by 38 publications

References 13 publications

Sun/shade adaptations of the photosynthetic apparatus of Hoya carnosa, an epiphytic CAM vine, in a subtropical rain forest in northeastern Taiwan

Sun/shade adaptations of the photosynthetic apparatus of Hoya carnosa, an epiphytic CAM vine, in a subtropical rain forest in northeastern Taiwan

Unusual Water Relations in the CAM Atmospheric Epiphyte Tillandsia usneoides L. (Bromeliaceae)

The role of physiological optima in shaping the geographic distribution of Spanish moss

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