Intermittent low temperatures constrain spring recovery of photosynthesis in boreal Scots pine forests

作者：Ingo Ensminger, Dmitry Sveshnikov, Douglas A. Campbell, Christiane Funk, Stefan Jansson, Jon Lloyd, Olga Shibistova, Gunnar Öquist · 发表于：Global Change Biology · 年份：2004 · DOI：10.1111/j.1365-2486.2004.00781.x · 被引用次数：247 · 研究领域：Photosynthetic Processes and Mechanisms、Plant responses to elevated CO2、Plant Water Relations and Carbon Dynamics

Abstract During winter and early spring, evergreen boreal conifers are severely stressed because light energy cannot be used when photosynthesis is pre‐empted by low ambient temperatures. To study photosynthetic performance dynamics in a severe boreal climate, seasonal changes in photosynthetic pigments, chloroplast proteins and photochemical efficiency were studied in a Scots pine forest near Zotino, Central Siberia. In winter, downregulation of photosynthesis involved loss of chlorophylls, a twofold increase in xanthophyll cycle pigments and sustained high levels of the light stress‐induced zeaxanthin pigment. The highest levels of xanthophylls and zeaxanthin did not occur during the coldest winter period, but rather in April when light was increasing, indicating an increased capacity for thermal dissipation of excitation energy at that time. Concomitantly, in early spring the D1 protein of the photosystem II (PSII) reaction centre and the light‐harvesting complex of PSII dropped to their lowest annual levels. In April and May, recovery of PSII activity, chloroplast protein synthesis and rearrangements of pigments were observed as air temperatures increased above 0°C. Nevertheless, severe intermittent low‐temperature episodes during this period not only halted but actually reversed the physiological recovery. During these spring low‐temperature episodes, protective processes involved a complementary function of the PsbS and early light‐induced protein thylakoid proteins. Fu...