Solar UV Upregulates Photoprotection but Slows Photosynthesis in Subalpine Australian Plants

Salter, William T.; Turnbull, Tarryn L.; Rennenberg, Heinz; Adams, Mark A.

doi:10.1657/aaar0017-024

Cited by 3 publications

(1 citation statement)

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“…(2) excess light energy, causing reaction centres to close, is dissipated through xanthophyll-cycle pigments (carotenoids) zeaxanthin and antheraxanthin in a process regulated by the pH the thylakoid lumen (Adams et al 2004;Murchie and Lawson 2013); (3) additionally antioxidants such as phenolic compounds are accumulated to quench reactive oxygen species (ROS) (Agati et al 2013;Hideg et al 2013;Salter et al 2017). It is reasonable to assume that the pressure on these mechanisms is increased when a plant is subject to both fluctuating temperatures and irradiances above the snowpack rather than the more stable conditions offered under snow (Loik et al 2004;Preece and Phoenix, 2013).…”

Section: Introductionmentioning

confidence: 99%

UV-screening and springtime recovery of photosynthetic capacity in leaves of Vaccinium vitis-idaea above and below the snow pack

Solanki¹,

Aphalo²,

Neimane³

et al. 2019

Plant Physiology and Biochemistry

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Evergreen plants in boreal biomes undergo seasonal hardening and dehardening adjusting their photosynthetic capacity and photoprotection; acclimating to seasonal changes in temperature and irradiance. Leaf epidermal ultraviolet (UV)-screening by flavonols responds to solar radiation, perceived in part through increased ultraviolet-B (UV-B) radiation, and is a candidate trait to provide cross-photoprotection. At Hyytiälä Forestry Station, central Finland, we examined whether the accumulation of flavonols was higher in leaves of Vaccinium vitis-idaea L. growing above the snowpack compared with those below the snowpack. We found that leaves exposed to colder temperatures and higher solar radiation towards the top of hummocks suffered greater photoinhibition than those at the base of hummocks. Epidermal UV-screening was highest in upper-hummock leaves, particularly during winter when lower leaves were beneath the snowpack. There was also a negative relationship between indices of flavonols and anthocyanins across all leaves suggesting fine-tuning of flavonoid composition for screening vs. antioxidant activity in response to temperature and irradiance. However, the positive correlation between the maximum quantum yield of photosystem II photochemistry (F/F) and flavonol accumulation in upper hummock leaves during dehardening did not confer on them any greater cross-protection than would be expected from the general relationship of F/F with temperature and irradiance (throughout the hummocks). Irrespective of timing of snow-melt, photosynthesis fully recovered in all leaves, suggesting that V. vitis-idaea has the potential to exploit the continuing trend for longer growing seasons in central Finland without incurring significant impairment from reduced duration of snow cover.

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