Drought resistance and recovery of photosystem II activity in a Mediterranean semi-deciduous shrub at the seedling stage

Abstract

Phlomis fruticosa is one of the main species of post-fire Mediterranean communities, occupying areas with post-fire grazing or altered precipitation pattern and consequently water stress imposed on seedlings of co-occurring species. Seedlings of woody perennials often differ from their mature individuals regarding their resistance of photosynthetic performance to environmental stresses. Such differences have been reported for tree species but there is a lack of information regarding shrub species. In the present study, we tried to detect changes in (PSII) activity imposed by water stress in P. fruticosa seedlings as well as its capability for recovery after rehydration. Maximum PSII photochemical efficiency decreased only under severe water stress exactly as in mature plants in the field. However, leaf chlorophyll (Chl) content was almost stable regardless of leaf relative water content (RWC). We assume that the photoprotective chlorophyll loss process, reported for many mature Mediterranean species (including P. fruticosa), has not yet been developed at the seedling stage. On the other hand, photoprotection through an increase of the relative amount of non-Q B -reducing centers was found during dehydration. Non-photochemical quenching (NPQ) contributed to protection from photodamage until moderate water stress but was significantly suppressed under severe water stress. Both processes were reversed after rehydration. The above characteristics enabled seedlings not only to survive during aggravating drought but also to maintain a considerable part of their effective quantum yield and perform significant electron transport even at extremely low relative water content (RWC). This was confirmed with measurements in a semi-natural environment (pots) and under real steady state conditions regarding adaptation of the photosynthetic machinery to prevailing light intensities.

Mechanism of xanthophyll-cycle-mediated photoprotection in Cerasus humilis seedlings under water stress and subsequent recovery

“…But the reduction was not sustained after rewatering and up to control levels by the end of 7-d recovery. An analogous transient drop during water deficit and recovery was detected in seedlings of Phlomis fruticosa (Petsas and Grammatikopoulos 2009). We can assume that it was probably due to higher drought resistance of these species.…”

Detection of Photosynthetic Performance of Stipa bungeana Seedlings under Climatic Change using Chlorophyll Fluorescence Imaging

“…The limitation on CO 2 assimilation may damage the balance between photochemical activity in photosystem II (PSII) and electron requirement for photosynthesis, resulting in the photodamage of PSII centers. Although plant photosynthetic apparatus appears to be highly resistant to water deficit (Giardi et al, 1996 ; Petsas and Grammatikopoulos, 2009 ; Zivcak et al, 2014 ), temperature rising can change the response of photosynthesis to water stress (Chaves et al, 2002 ). Among all plant physiological activities, photosynthesis has been proved to be most sensitive to high temperature and can be inhibited entirely by heat stress before other plant physiological symptoms occur (Berry and Bjorkman, 1980 ).…”

Vegetative growth, compatible solute accumulation, ion partitioning and chlorophyll fluorescence of 'Malas-e-Saveh' and 'Shishe-Kab' pomegranates in response to salinity stress

“…Chlorophyll (Chl) fluorescence yield can show stress or damage to the photosynthetic apparatus (Glynn et al 2003). Various reports focus on Chl fluorescence parameters in plants subjected to drought (Petsas andGrammatikopoulos 2009, Khaleghi et al 2012), freezing (Percival and Fraser 2001), ozone (Meinander et al 1996), and salinity (Ranjbarfordoei et al 2006, García-Sánchez and Syvertsen 2006, Kalaji et al 2011. Jain and Dass (1988) and Patil and Waghmare (1982) reported that plant height, number of leaves, and stem diameter of pomegranate plants decreased significantly with increasing soil salinity.…”