Mechanisms of photoprotection in overwintering evergreen conifers: Sustained quenching of chlorophyll fluorescence

Liu, Mingyu; Wang, Yu; Zhang, Huihui; Hao, Yuanqin; Wu, Haibo; Shen, Hailong; Zhang, Peng

doi:10.1016/j.plaphy.2024.108638

Cited by 4 publications

(1 citation statement)

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“…developed various survival mechanisms to endure adverse climatic conditions such as drought, cold temperatures, and nutrient scarcity, ensuring continuous photosynthesis throughout the year(Wyka and Oleksyn 2014;Liu et al 2024;Verhoeven and Kornkven 2024). Our research reveals that ageing needles maintain high PSII efficiency, dynamically adjust the Chla/Chlb ratio and Car/Chltot ratio to effectively capture light in changing light environments, and manage their energetic budget to compromise photosynthetic capacity with varying light conditions and energy partitioning among different photosynthetic processes and losses.Oleksyn et al (2020) demonstrated that across a 1000 km transect in Scots pine forests in Sweden, plants in modern conditions (circa 2015), growing in 1°C warmer climates, have longer needles and shorter needle lifespans compared to plants a century ago (circa 1915).…”

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confidence: 88%

Adaptive significance of age- and light-related variation in needle structure, photochemistry, and pigments in evergreen coniferous trees

Oluborode,

Chadzinikolau,

Formela-Luboińska

et al. 2024

Preprint

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Evergreen conifers thrive in challenging environments by maintaining multiple sets of needles, optimizing photosynthesis even under harsh conditions. This study aimed to investigate the relationships between needle structure, photosynthetic parameters, and age along the light gradient in the crowns of Abies alba, Taxus baccata, and Picea abies. We hypothesized that: (1) Needle structure, photochemical parameters, and photosynthetic pigment content would correlate with needle age and light levels in tree crowns. (2) The photosynthetic capacity of ageing needles would decline and adjust to the increasing self-shading of branches. Our results revealed a non-linear increase in the leaf mass-to-area ratio. The maximum quantum yield of photosystem II photochemistry decreased linearly with needle age without reaching levels indicative of photoinhibition. Decreased maximum electron transport rates (ETRmax) were linked to declining values of saturation photosynthetic photon flux and increasing non-photochemical quenching of fluorescence (NPQ), indicating energy losses as heat. The chlorophyll a to chlorophyll b ratio linearly decreased, suggesting older needles sustain high light capture efficiency. These findings offer new insights into the combined effects of needle ageing and self-shading on photochemistry and pigment content. This functional needle balance highlights the trade-off between the costs of long-term needle retention and the benefits of efficient resource utilization. In environments where air temperature is less of a constraint on photosynthesis due to climate warming, evergreen coniferous trees could sustain or enhance their photosynthetic capacity. They can achieve this by shortening needle lifespan and retaining fewer cohorts of needles with higher ETRmax and lower NPQ compared to older needles.

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confidence: 88%