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Strategies of light energy utilisation, dissipation and attenuation in six co-occurring alpine heath species in Tasmania

journal contribution
posted on 2023-05-16, 14:20 authored by Williams, EL, Mark HovendenMark Hovenden, Dugald CloseDugald Close
Alpine environments are characterised by low temperatures and high light intensities. This combination leads to high light stress owing to the imbalance between light energy harvesting and its use in photochemistry. In extreme cases, high light stress can lead to the level of photo-oxidative damage exceeding the rate of repair to the photosynthetic apparatus. Plant species may vary in the mechanisms they use to prevent photodamage, but most comparisons are of geographically and ecologically distinct species. Differences in leaf colouration suggested that photoprotective strategies might differ among Tasmanian evergreen alpine shrub species. We compared chlorophyll fluorescence and leaf pigment composition in six co-occurring alpine shrub species on the summit of Mt Wellington, southern Tasmania, Australia, during spring and autumn. We found marked differences among species in light energy utilisation, attenuation and dissipation. Ozothamnus ledifolius maintained a large capacity for photosynthetic light utilisation and thus, had a low requirement for light dissipation. All five of the other species relied on xanthophyll-cycle- dependent thermal energy dissipation. In addition Epacris serpyllifolia, Richea sprengelioides and Leptospermum rupestre had foliar anthocyanins that would attenuate photosynthetically active light in the leaf. During spring, all species retained de-epoxidised xanthophylls through the night and the pre-dawn concentration of antheraxanthin and zeaxanthin was significantly correlated with reductions in pre-dawn F v/F m. We propose that these species use three photoprotective strategies to cope with the combination of high light and low temperature.

History

Publication title

Functional Plant Biology

Volume

30

Issue

12

Pagination

1205-1218

ISSN

1445-4408

Department/School

School of Natural Sciences

Publisher

CSIRO Publishing

Place of publication

Australia

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the environmental sciences

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