Seasonal, Sex- and Plant Size-Related Effects on Photoinhibition and Photoprotection in the Dioecious Mediterranean Dwarf Palm, Chamaerops humilis

Abstract

In Mediterranean-type ecosystems plants are exposed to several adverse environmental conditions throughout the year, ranging from drought stress during the warm and dry summers to chilling stress due to the typical drop in temperatures during winters. Here we evaluated the ecophysiological response, in terms of photoinhibition and photoprotection, of the dioecious Mediterranean palm, Chamaerops humilis to seasonal variations in environmental conditions. Furthermore, we considered as well the influence of plant size, maturity, and sexual dimorphism. Results showed evidence of winter photoinhibition, with a marked decrease of the Fv/Fm ratio below 0.7 between January and March, which was coincident with the lowest temperatures. During this period, the de-epoxidation state of the xanthophyll cycle and zeaxanthin levels increased, which might serve as a photoprotection mechanism, owing the full recovery from winter photoinhibition during spring. Furthermore, mature plants showed lower chlorophyll levels and higher β-carotene levels per unit of chlorophyll than juvenile plants, and females displayed lower leaf water contents and higher photoinhibition than males during summer, probably due to increased reproductive effort of females. However, neither low temperatures during winter nor reproductive events in females during the summer led to irreversible damage to the photosynthetic apparatus. We conclude that (i) the Mediterranean dwarf palm, C. humilis, suffers from photoinhibition during winter, but this is transient and does not lead to irreversible damage, and (ii) females from this plant species are more sensitive than males to photoinhibition during reproductive events.

Photochemistry and Antioxidative Capacity of Female and Male Taxus baccata L. Acclimated to Different Nutritional Environments

“…Contrary to our first hypothesis, higher F v /F m in needles of female individuals indicates that they had a potentially higher capacity of light absorption, but it also means that they had been adapted to the low light environment and were thus more threatened by photoinhibition when exposed to high light compared with males (Maxwell and Johnson, 2000 ; Wyka et al, 2007 ). Our results are in agreement with the earlier findings of Xu et al ( 2008 ) and Morales et al ( 2016 ) suggesting that females are generally more sensitive to photoinhibition than males.…”

Ecophysiological differentiation between two invasive species ofCarpobrotuscompeting under different nutrient conditions

“…A decrease in the F v / F m values below 0.8 has been considered symptomatic of stress‐dependent photoinhibition (Björkman and Demmig, ; Kalaji et al., ). In this regard, winter photoinhibition is a recognized phenomenon in some Mediterranean species, as a consequence of the low temperatures, short photoperiods, and clear days with elevated irradiance (Oliveira and Peñuelas, ; Morales et al., ). Our findings suggest a negative effect of low temperature on the photochemical performance of both taxa, particularly on the efficiency of capture of the excitation energy by open PSII reaction centers (Krause and Weis, ; Mohammed et al., ).…”

Gender dimorphism in Corema album across its biogeographical area and implications under a scenario of extreme drought events

“…Yet, we found no signs of gender dimorphism in the photosynthetic response. Other studies have found signs of higher photoinhibition in female plants of dioecious species, associated to the reproductive period and drought stress, as it has been reported in the dwarf palm Chamaerops humilis (Morales et al, 2016) and in the subdioecious species Honckenya peploides (Sánchez-Vilas and Retuerto, 2011). Or what is more, when comparing reproductive and non-reproductive shoots of female Pistacia lentiscus, higher photoinhibition was observed in reproductive shoots (Juvany et al, 2014).…”

“…On the other hand, in order to produce pollen, male plants should need more nitrogen supply than females, which may lead to different resource demands (Barrett and Hough, 2013); these differences should be more important in wind-pollinated plants during the flowering period, generating a trade-off in the investment of growth and reproduction (Obeso, 2002;Zunzunegui et al, 2006). In relation to these ideas, in the literature there are many studies on gender distribution, morphology, growth and survival in dioecious plants (Allen and Antos, 1993;Álvarez-Cansino et al, 2010a;Diaz-Barradas and Correia, 1999;Herrera, 1988;Morales et al, 2016;Nicotra, 1999;Obeso, 1997;Zunzunegui et al, 2006). Yet, studies on genderspecific physiology in dioecious species are limited (Álvarez-Cansino et al, 2012;Álvarez-Cansino et al, 2010b;Correia and Díaz Barradas, 2000;Dawson et al, 2004;Dawson and Ehleringer, 1993;Juvany et al, 2014;Juvany and Munné-Bosch, 2015;Sánchez-Vilas and Retuerto, 2009).…”