Changes in chlorophyll a fluorescence, photosynthetic CO 2 assimilation and xanthophyll cycle interconversions during dehydration in desiccation-tolerant and intolerant liverworts

Deltoro, Vicente I.; Calatayud, Ángeles; Gimeno, Cristina; Abadı́a, Anunciación; Barreno, Eva

doi:10.1007/s004250050476

Cited by 86 publications

(53 citation statements)

References 24 publications

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“…Carotenoids and other compounds, such as abietane diterpenes, have received little attention despite their capacity to scavenge singlet oxygen and lipid peroxy-radicals, as well as to inhibit lipid peroxidation and superoxide generation under dehydrative forces (Deltoro et al, 1998). The transcript of some of the antioxidant genes such as glutathione reductase or ascorbate peroxidase was higher during recovery from a water deficit period and appeared to play a role in the protection of cellular machinery against damage by reactive oxygen species (Ratnayaka et al, 2003).…”

Section: Antioxidant Defensementioning

confidence: 99%

Plant Drought Stress: Effects, Mechanisms and Management

Farooq

Wahid²,

Kobayashi³

et al. 2009

Sustainable Agriculture

1,345

1,169

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-Scarcity of water is a severe environmental constraint to plant productivity. Drought-induced loss in crop yield probably exceeds losses from all other causes, since both the severity and duration of the stress are critical. Here, we have reviewed the effects of drought stress on the growth, phenology, water and nutrient relations, photosynthesis, assimilate partitioning, and respiration in plants. This article also describes the mechanism of drought resistance in plants on a morphological, physiological and molecular basis. Various management strategies have been proposed to cope with drought stress. Drought stress reduces leaf size, stem extension and root proliferation, disturbs plant water relations and reduces water-use efficiency. Plants display a variety of physiological and biochemical responses at cellular and whole-organism levels towards prevailing drought stress, thus making it a complex phenomenon. CO 2 assimilation by leaves is reduced mainly by stomatal closure, membrane damage and disturbed activity of various enzymes, especially those of CO 2 fixation and adenosine triphosphate synthesis. Enhanced metabolite flux through the photorespiratory pathway increases the oxidative load on the tissues as both processes generate reactive oxygen species. Injury caused by reactive oxygen species to biological macromolecules under drought stress is among the major deterrents to growth. Plants display a range of mechanisms to withstand drought stress. The major mechanisms include curtailed water loss by increased diffusive resistance, enhanced water uptake with prolific and deep root systems and its efficient use, and smaller and succulent leaves to reduce the transpirational loss. Among the nutrients, potassium ions help in osmotic adjustment; silicon increases root endodermal silicification and improves the cell water balance. Low-molecular-weight osmolytes, including glycinebetaine, proline and other amino acids, organic acids, and polyols, are crucial to sustain cellular functions under drought. Plant growth substances such as salicylic acid, auxins, gibberrellins, cytokinin and abscisic acid modulate the plant responses towards drought. Polyamines, citrulline and several enzymes act as antioxidants and reduce the adverse effects of water deficit. At molecular levels several drought-responsive genes and transcription factors have been identified, such as the dehydration-responsive element-binding gene, aquaporin, late embryogenesis abundant proteins and dehydrins. Plant drought tolerance can be managed by adopting strategies such as mass screening and breeding, marker-assisted selection and exogenous application of hormones and osmoprotectants to seed or growing plants, as well as engineering for drought resistance. drought response / stomatal oscillation / osmoprotectants / hormones / stress proteins / drought management / CO 2

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Section: Antioxidant Defensementioning

confidence: 99%

Plant Drought Stress: Effects, Mechanisms and Management

Farooq

Wahid²,

Kobayashi³

et al. 2009

Sustainable Agriculture

1,345

1,169

View full text Add to dashboard Cite

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“…Individual sample correlations with  PSII were again generally stronger than when all the samples were pooled (r D 0Ð47, p < 0Ð0001), although when the samples of S. pulchrum and S. capillifolium were removed from the group the correlation increased (r D 0Ð77, p < 0Ð0001) indicating a broadly similar trend amongst the remaining samples (Figure 3). Variable relationships between the PRI and measures of photosynthetic activity are likely to be driven by species-specific differences in the regulation of photosynthetic and photoprotective processes, in response to water loss (Deltoro et al, 1998). However, further complexity may be added to the correct interpretation of PRI/ PSII relationships if samples experience differing in situ antecedent environmental conditions.…”

Section: Spectral Reflectance and Sphagnum  Psiimentioning

confidence: 99%

“…Under environmental stresses, such as progressive drought, plants must therefore employ specific mechanisms to safely dissipate this excess energy. The exact physiological processes that occur in mosses, which enable energy dissipation, are poorly understood (Deltoro et al, 1998), although it is widely accepted that plants dissipate excess energy either as heat or re-emit the energy as light, a process known as chlorophyll fluorescence Adams, 1992, 2006). Heat dissipation (or non-photochemical quenching) is commonly thought to occur via conversion of xanthophyll cycle pigments into their photoprotective state (Demmig-Adams and Adams, 1992;Horton et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Spectral reflectance and photosynthetic properties of Sphagnum mosses exposed to progressive drought

Harris

2008

Ecohydrology

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This article explores the utility of spectral reflectance signals to assess changes in the photosynthetic efficiency ( PSII ) of Sphagnum mosses exposed to reductions in water availability. Reflectance was measured in parallel to moisture content and chlorophyll fluorescence in five species of Sphagnum exposed to progressive drought. Decreases in moisture availability caused a significant reduction in  PSII for all samples tested. An objective was to ascertain whether Sphagnum  PSII was better correlated with (i) spectral indices directly related to photosynthetic processes through association with xanthophyll cycle pigmentation (the photochemical reflectance index; PRI), or (ii) indices indirectly correlated with photosynthetic activity but able to detect changes in canopy morphology (the normalized difference vegetation index; NDVI), chlorophyll stability (the structure insensitive pigment index; SIPI), or canopy moisture content (the floating water band index; fWBI). Strongest correlations were found between  PSII and indices which were indirectly related to  PSII . Both the SIPI and the NDVI exhibited linear correlations although these relationships were sometimes sample-specific. The fWBI was the index least affected by sample-specific relationships and showed a strong curvilinear correlation with  PSII . Photosynthetic efficiency was correlated with the PRI but relationships were much weaker than for the other indices used, and in some cases negative. The NDVI and the fWBI show the most potential for monitoring Sphagnum photosynthetic activity at the ecosystem scale. The results from this study will help to monitor and understand the responses of these key species to hydrological disturbances.

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“…Therefore, survival of drought-resistant organisms under extreme light conditions suggests highly eective mechanisms of photoprotection. Indeed, Deltoro et al (1998) have shown that a desiccationtolerant liverwort had a higher non-radiative dissipation of light energy than a desiccation-sensitive counterpart.…”

Section: Introductionmentioning

confidence: 99%

Phototolerance of lichens, mosses and higher plants in an alpine environment: analysis of photoreactions

Heber

Bilger²,

Bligny

et al. 2000

Planta

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Adaptation to excessive light is one of the requirements of survival in an alpine environment particularly for poikilohydric organisms which in contrast to the leaves of higher plants tolerate full dehydration. Changes in modulated chlorophyll fluorescence and 820-nm absorption were investigated in the lichens Xanthoria elegans (Link) Th. Fr. and Rhizocarpon geographicum (L.) DC, in the moss Grimmia alpestris Limpr. and the higher plants Geum montanum L., Gentiana lutea L. and Pisum sativum L., all collected at altitudes higher than 2000 m above sea level. In the dehydrated state, chlorophyll fluorescence was very low in the lichens and the moss, but high in the higher plants. It increased on rehydration in the lichens and the moss, but decreased in the higher plants. Light-induced charge separation in photosystem II was indicated by pulse-induced fluorescence increases only in dried leaves, not in the dry moss and dry lichens. Strong illumination caused photodamage in the dried leaves, but not in the dry moss and dry lichens. Light-dependent increases in 820-nm absorption revealed formation of potential quenchers of chlorophyll fluorescence in all dehydrated plants, but energy transfer to quenchers decreased chlorophyll fluorescence only in the moss and the lichens, not in the higher plants. In hydrated systems, coupled cyclic electron transport is suggested to occur concurrently with linear electron transport under strong actinic illumination particularly in the lichens because far more electrons became available after actinic illumination for the reduction of photo-oxidized P700 than were available in the pool of electron carriers between photosystems II and I. In the moss Grimmia, but not in the lichens or in leaves, light-dependent quenching of chlorophyll fluorescence was extensive even under nitrogen, indicating anaerobic thylakoid acidification by persistent cyclic electron transport. In the absence of actinic illumination, acidification by ca. 8% CO2 in air quenched the initial chlorophyll fluorescence yield Fo only in the hydrated moss and the lichens, not in leaves of the higher plants. Under the same conditions, 8% CO2 reduced the maximal fluorescence yield Fm strongly in the poikilohydric organisms, but only weakly or not at all in leaves. The data indicate the existence of deactivation pathways which enable poikilohydric organisms to avoid photodamage not only in the hydrated but also in the dehydrated state. In the hydrated state, strong nonphotochemical quenching of chlorophyll fluorescence indicated highly sensitive responses to excess light which facilitated the harmless dissipation of absorbed excitation energy into heat. Protonation-dependent fluorescence quenching by cyclic electron transport, P700 oxidation and, possibly, excitation transfer between the photosystems were effectively combined to produce phototolerance.

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Changes in chlorophyll a fluorescence, photosynthetic CO 2 assimilation and xanthophyll cycle interconversions during dehydration in desiccation-tolerant and intolerant liverworts

Cited by 86 publications

References 24 publications

Plant Drought Stress: Effects, Mechanisms and Management

Plant Drought Stress: Effects, Mechanisms and Management

Spectral reflectance and photosynthetic properties of Sphagnum mosses exposed to progressive drought

Phototolerance of lichens, mosses and higher plants in an alpine environment: analysis of photoreactions

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