scholarly journals The diatomPhaeodactylum tricornutumadjusts nonphotochemical fluorescence quenching capacity in response to dynamic light via fine-tuned Lhcx and xanthophyll cycle pigment synthesis

2016 ◽  
Vol 214 (1) ◽  
pp. 205-218 ◽  
Author(s):  
Bernard Lepetit ◽  
Gautier Gélin ◽  
Mariana Lepetit ◽  
Sabine Sturm ◽  
Sascha Vugrinec ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Xanthophyll Cycle ◽  
Pigment Synthesis ◽  
Xanthophyll Cycle Pigment

scholarly journals Autumn Warming Delays the Downregulation of Photosynthesis and Does Not Increase the Risk of Freezing Damage in Interior and Coastal Douglas-fir

2021 ◽  
Vol 4 ◽  
Author(s):  
Devin Noordermeer ◽  
Vera Marjorie Elauria Velasco ◽  
Ingo Ensminger
Keyword(s):  
Cold Acclimation ◽  
Freezing Tolerance ◽  
Xanthophyll Cycle ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Photosynthetic Activity ◽  
Elevated Temperatures ◽  
Douglas Fir ◽  
The Impact ◽  
Xanthophyll Cycle Pigment

During autumn, evergreen conifers utilize the decrease in daylength and temperature as environmental signals to trigger cold acclimation, a process that involves the downregulation of photosynthesis, upregulation of photoprotection, and development of cold hardiness. Global warming will delay the occurrence of autumn low temperatures while daylength remains unaffected. The impact of autumn warming on cold acclimation and the length of the carbon uptake period of species with ranges that encompass diverse climates, such as Douglas-fir (Pseudotsuga menziesii), remains unclear. Our study investigated intraspecific variation in the effects of autumn warming on photosynthetic activity, photosynthetic pigments, and freezing tolerance in two interior (var. glauca) and two coastal (var. menziesii) Douglas-fir provenances. Following growth under simulated summer conditions with long days (16 h photoperiod) and summer temperatures (22/13°C day/night), Douglas-fir seedlings were acclimated to simulated autumn conditions with short days (8 h photoperiod) and either low temperatures (cool autumn, CA; 4/−4°C day/night) or elevated temperatures (warm autumn, WA; 19/11°C day/night). Exposure to low temperatures in the CA treatment induced the downregulation of photosynthetic carbon assimilation and photosystem II efficiency, increased the size and de-epoxidation of the xanthophyll cycle pigment pool, and caused the development of sustained nonphotochemical quenching (NPQ). Seedlings in the WA treatment exhibited no downregulation of photosynthesis, no change in xanthophyll cycle pigment de-epoxidation, and no development of sustained NPQ. Albeit these changes, freezing tolerance was not impaired under WA conditions compared with CA conditions. Interior Douglas-fir seedlings developed greater freezing tolerance than coastal seedlings. Our findings suggest that autumn warming, i.e., short photoperiod alone, does not induce the downregulation of photosynthesis in Douglas-fir. Although autumn warming delays the downregulation of photosynthesis, the prolonged period of photosynthetic activity does not bear a trade-off of impaired freezing tolerance.

Autumn warming delays downregulation of photosynthesis and does not increase risk of freezing damage in interior and coastal Douglas-fir seedlings

2020 ◽  
Author(s):  
Devin Noordermeer ◽  
Vera Velasco ◽  
Ingo Ensminger
Keyword(s):  
Low Temperature ◽  
Freezing Tolerance ◽  
Xanthophyll Cycle ◽  
Photosynthetic Activity ◽  
Nonphotochemical Quenching ◽  
Douglas Fir ◽  
Cold Hardening ◽  
Freezing Damage ◽  
Increase Risk ◽  
Xanthophyll Cycle Pigment

<p>In the next several decades, warming in the northern hemisphere will result in asynchronous phasing between the temperature and photoperiod signals that evergreen conifers rely upon for cold hardening during autumn. Our study investigated intraspecific variation in photosynthetic and photoprotective mechanisms in Douglas-fir (Pseudotsuga menziesii) originating from contrasting climates during simulated summer and autumn conditions, as well as how autumn warming affects downregulation of photosynthesis and development of cold hardening. Following growth under long days and summer temperature (LD/ST; 16 h photoperiod; 22 °C/13 °C day/night), Douglas-fir seedlings from two interior and two coastal provenances were acclimated to simulated autumn conditions with short days and either low temperature (SD/LT; 8 h photoperiod; 4 °C/-4 °C day/night) or high temperature (SD/HT; 8 h photoperiod; 19 °C/11 °C day/night). Exposure to low temperature induced increase in size and de-epoxidation of the xanthophyll cycle pigment pool, development of sustained nonphotochemical quenching, and downregulation of photosynthetic activity. SD/HT seedlings exhibited no downregulation of photosynthesis, corresponding with no change in xanthophyll cycle pigment de-epoxidation and no development of sustained nonphotochemical quenching. However, freezing tolerance development for all provenances was not impaired under SD/HT relative to SD/LT. Interior Douglas-fir provenances developed greater freezing tolerance relative to coastal provenances under both temperature treatments. Our findings suggest that short photoperiod alone is insufficient to induce downregulation of photosynthesis in autumn for Douglas-fir. However, this prolonged period of photosynthetic activity does not appear to bear a trade-off of impaired freezing tolerance.</p>

Sign in / Sign up

Export Citation Format

Share Document