Expression of low molecular weight heat‐shock proteins and total antioxidant activity in the Mediterranean tree Quercus ilex L. in relation to seasonal and diurnal changes in physiological parameters

Abstract

The total antioxidant activity (TAA) and the accumulation of small heat shock proteins (sHsps) were analysed under field conditions in Quercus ilex with regard to organ ontogeny and the physiological state of the plant. The results point toward the participation of sHsps and an increase of TAA in the general adaptation syndrome (GAS) of woody Mediterranean evergreens. In leaves and stems, there was a definite TAA seasonal pattern but no effect from diurnal variations or from the current stage of organ ontogeny. TAA was about twice as large in summer as in spring and winter and the hydrophilic antioxidant content was about 16 times greater than that of lipophilic antioxidants. The accumulation of sHsps in leaves also showed a seasonal pattern, but no effect from diurnal variations or from leaf ontogeny. In summer days, the sHsps content remained invariable even during the daylight hours in which the leaves were physiologically recovered. However, the accumulation of sHsps in stems did vary in relation to organ ontogeny. Old stems had a high accumulation of sHsps throughout the year, whereas in young stems, accumulation of sHsps was detected only in summer. This is probably due to a higher quantity of lignified and suberized tissues in the older stems. Using two-dimensional immunodetection for leaves and stems, two sets of Hs protein species (17 and 10 kDa regions) were observed. In stems, there was an increase in 10 kDa proteins from winter to summer. These results are discussed and the possible role of the two types of polypeptides in the face of environmental and endogenous oxidative stress are considered.

A molecular approach to drought‐induced reduction in leaf CO2 exchange in drought‐resistant Quercus ilex

“…Our data showed primary metabolic adjustments to (1) maintain photosynthetic carbon uptake at mild drought stress, and (2) to protect leaves from oxidative damage at more severe levels of drought stress. Additional adjustments involving the production of small heat shock proteins (Verdaguer et al ), peroxidases (Echevarría‐Zomeño et al ) and terpenes (Peñuelas and Llusià , Blanch et al ) have been observed in Q. ilex leaves under high temperatures and low water availability. These adjustments also act against oxidative stress by increasing thermotolerance, ROS scavenging or cell repairing.…”

Leaf flavonoid content in Quercus ilex L. resprouts and its seasonal variation

“…Other mechanisms account for the photoprotective defence in the winter in Q. ilex, increased activity of total hydrophilic antioxidants (Verdaguer et al 2003), increased ascorbate content (García-Plazaola et al 1999), and increases in the polyamine, putrescine (Pintó-Marijuan et al 2006. The flavonol-hexosides detected in highest amount in this season might also contribute to photoprotection (Winkel-Shirley 2002).…”

Constitutive Expression of a Tomato Small Heat Shock Protein Gene LeHSP21 Improves Tolerance to High-Temperature Stress by Enhancing Antioxidation Capacity in Tobacco

“…Gene expression of some sHSPs has been detected in all plant tissues under different conditions (Almoguera et al 1993;Coca et al 1996;Sun et al 2001;Verdaguer et al 2003;Swindell 2006;Swindell et al 2007;Qin et al 2008;Siddique et al 2008;Waters et al 2008;Sarkar et al 2009;Weston et al 2011;Haq et al 2013;Merino et al 2014;Park et al 2015). In rice, the Oshsp26 gene was induced by heat stress: the transcript level was the highest when rice leaves were treated at 42°C for 2 h. It was also found that Oshsp26 gene was expressed following oxidative stress even in the absence of heat stress (Lee et al 2000).…”