Dynamics of Tissue Heat Tolerance and Thermotolerance of PS II in Alpine Plants

Neuner, Gilbert; Buchner, Othmar

doi:10.1007/978-3-7091-0136-0_6

Cited by 30 publications

(49 citation statements)

References 54 publications

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“…Natural cooling rates below 0°C in leaves of alpine plants did not exceed -2K.h -1 (mean rate: -0.3 K.h -1 ; Neuner and Buchner, 2012). Exceptionally more rapid cooling rates, however, cannot be fully excluded, as reported by Körner (2012).…”

Section: Plant Minimum Temperaturesmentioning

confidence: 87%

Frost resistance in alpine woody plants

Neuner

2014

Front. Plant Sci.

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101

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This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone.

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Section: Plant Minimum Temperaturesmentioning

confidence: 87%

Frost resistance in alpine woody plants

Neuner

2014

Front. Plant Sci.

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101

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“…Since the temperature optimum of photosynthesis is usually close to mean growing season temperature (Fryer and Ledig, 1972;Lambers et al, 2008), thermal coupling seems to be a good strategy to maintain optimal conditions for carbon assimilation. Moreover, coupling may prevent overheating during sunny days since initial heat damage in alpine plants can develop within only one hour after the critical temperature threshold of about 30 °C is surpassed (Neuner and Buchner, 2012). Reduced daily air temperature fluctuations on the humid and cooler eastern side provide a distinctly narrower thermal envelope.…”

Section: Discussionmentioning

confidence: 99%

Fine-Scale Patterns of Soil and Plant Surface Temperatures in an Alpine Fellfield Habitat, White Mountains, California

Graham

Rundel

Kaiser

et al. 2012

Arctic, Antarctic, and Alpine Research

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“…Many heat tolerance data have been collected during the last centuries using laboratory based test procedures e.g. [14-19], however, ecologically significant data on heat tolerance of plants obtained in in situ measurements on plants at their specific growing site are widely missing and mechanisms of recuperation and repair appear severely understudied.…”

Section: Introductionmentioning

confidence: 99%

A novel system for in situ determination of heat tolerance of plants: first results on alpine dwarf shrubs

et al. 2013

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BackgroundHeat stress and heat damage to plants gain globally increasing importance for crop production and plant survival in endangered habitats. Therefore the knowledge of heat tolerance of plants is of great interest. As many heat tolerance measurement procedures require detachment of plants and protocols expose samples to various heat temperatures in darkness, the ecological relevance of such results may be doubted. To overcome these constraints we designed a novel field compatible Heat Tolerance Testing System (HTTS) that opens the opportunity to induce controlled heat stress on plants in situ under full natural solar irradiation. Subsequently, heat tolerance can be evaluated by a variety of standard viability assays like the electrolyte leakage test, chlorophyll fluorescence measurements and visual assessment methods. Furthermore, recuperation can be studied under natural environmental conditions which is impossible when detached plant material is used. First results obtained on three alpine dwarf - shrubs are presented.ResultsWhen heat tolerance of Vaccinium gaultherioides Bigelow was tested with the HTTS in situ, the visual assessment of leaves showed 50% heat injury (LT50) at 48.3°C, while on detached leaves where heat exposure took place in small heat chambers this already happened at 45.8°C. Natural solar irradiation being applied during heat exposure in the HTTS had significantly protective effects: In Loiseleuria procumbens L. (Desv.), if heat exposure (in situ) took place in darkness, leaf heat tolerance was 50.6°C. In contrast, when heat exposure was conducted under full natural solar irradiation heat tolerance was increased to 53.1°C. In Rhododendron ferrugineum L. heat tolerance of leaves was 42.5°C if the exposure took place ex situ and in darkness, while it was significantly increased to 45.8°C when this happened in situ under natural solar irradiation.ConclusionsThe results obtained with the HTTS tested in the field indicate a mitigating effect of natural solar irradiation during heat exposure. Commonly used laboratory based measurement procedures expose samples in darkness and seem to underestimate leaf heat tolerance. Avoidance of detachment by the use of the HTTS allows studying heat tolerance and recuperation processes in the presence of interacting external abiotic, biotic and genetic factors under field conditions. The investigation of combined effects of heat exposure under full solar irradiation, of recuperation and repair processes but also of possible damage amplification into the results with the HTTS appears to be particularly useful as it allows determining heat tolerance of plants with a considerably high ecological significance.

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Dynamics of Tissue Heat Tolerance and Thermotolerance of PS II in Alpine Plants

Cited by 30 publications

References 54 publications

Frost resistance in alpine woody plants

Frost resistance in alpine woody plants

Fine-Scale Patterns of Soil and Plant Surface Temperatures in an Alpine Fellfield Habitat, White Mountains, California

A novel system for in situ determination of heat tolerance of plants: first results on alpine dwarf shrubs

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