Effects of Temperature and Nutrient Supply on Resource Allocation, Photosynthetic Strategy, and Metabolic Rates of Synechococcus sp.

Abstract

Temperature and nutrient supply are key factors that control phytoplankton ecophysiology, but their role is commonly investigated in isolation. Their combined effect on resource allocation, photosynthetic strategy, and metabolism remains poorly understood. To characterize the photosynthetic strategy and resource allocation under different conditions, we analyzed the responses of a marine cyanobacterium (Synechococcus PCC 7002) to multiple combinations of temperature and nutrient supply. We measured the abundance of proteins involved in the dark (RuBisCO, rbcL) and light (Photosystem II, psbA) photosynthetic reactions, the content of chlorophyll a, carbon and nitrogen, and the rates of photosynthesis, respiration, and growth. We found that rbcL and psbA abundance increased with nutrient supply, whereas a temperature‐induced increase in psbA occurred only in nutrient‐replete treatments. Low temperature and abundant nutrients caused increased RuBisCO abundance, a pattern we observed also in natural phytoplankton assemblages across a wide latitudinal range. Photosynthesis and respiration increased with temperature only under nutrient‐sufficient conditions. These results suggest that nutrient supply exerts a stronger effect than temperature upon both photosynthetic protein abundance and metabolic rates in Synechococcus sp. and that the temperature effect on photosynthetic physiology and metabolism is nutrient dependent. The preferential resource allocation into the light instead of the dark reactions of photosynthesis as temperature rises is likely related to the different temperature dependence of dark‐reaction enzymatic rates versus photochemistry. These findings contribute to our understanding of the strategies for photosynthetic energy allocation in phytoplankton inhabiting contrasting environments.

Cyanobacterial growth and morphology are influenced by carboxysome positioning and temperature

“…It has recently been 375 found that low temperature growth (18 to 22 o C) results in increased RuBisCO levels in the 376 marine cyanobacterium Synechococcus PCC 7002, compared to growth at 26 o C or 30 o C (44).This trend was also observed in natural phytoplankton assemblages across a wide latitudinal range(35). Consistently, we found here that the RbcS-mTQ signal within carboxysome foci, and within the entire cell, inversely correlated with decreasing growth temperatures.Previous studies have also shown positive relationships between growth rate and RuBisCO abundance(35,(44)(45)(46)(47)(48). Elevated carbon fixation rates during blooms in polar regions have been shown to be associated with several-fold increases in RuBisCO.…”

Rising nutrient nitrogen reverses the impact of temperature on photosynthesis and respiration of a macroalga Caulerpa lentillifera (Ulvophyceae, Caulerpaceae)

“…6). Available nitrogen is necessary for buildup of cellular materials (Li et al 2015); therefore, the increase of nutrient nitrogen is understandable to increase cellular N-contained matters, especially the N-rich proteins or nucleic acids (Davison 1991;Menéndez 2005;Fernandez-Gonzalez et al 2020). Algal maximal Nutilization ability often differs with varying temperatures, with a wider accepted range of N contents at lower temperature (Yu and Yang 2008;Ye et al 2013), as indicated by the alleviation of temperature dependency of photosynthetic capacity and Fig.…”

Development of photosynthetic carbon fixation model using multi-excitation wavelength fast repetition rate fluorometry in Lake Biwa

“…Furthermore, increasing temperature may lead to a state of chronic photoinhibition through photodamage [100], as well as changes in species composition of the community [40]. Although we did not examine the interaction among all explanatory variables, temperature may have affected Ф e,C vis-à-vis interaction with the other factors such as nutrient stoichiometry [101].…”