Physiological acclimation of two psammophytes to repeated soil drought and rewatering

Abstract

To understand physiological acclimation of psammophyte to repeated soil drought and rewatering, two psammophytes (Setaria viridis and Digitaria ciliaris) were subjected to three cycles of soil drought and rewatering. The response process of leaf relative water content (RWC), membrane permeability, lipid peroxidation, gas exchange characteristics, antioxidant enzymes, soluble protein, and free proline was examined. Leaf RWC, the net photosynthesis rate, stomatal conductance, and water use efficiency decreased, while membrane permeability, lipid peroxidation, intercellular CO 2 concentration, soluble protein, and free proline increased during three soil drought periods for both psammophytes. These physiological characteristics were recovered to the control levels following rewatering for 4 days. However, activities of SOD, CAT, and POD were induced continuously under soil drought conditions, and remained higher than those in the control throughout the whole experiment period, which agrees with our hypothesis that drought hardening activates defensive systems of both psammophytes continuously. Decreasing level of leaf RWC and increasing levels of leaf membrane permeability and lipid peroxidation were suppressed with increasing the number of drought cycles, suggesting that drought hardening alleviates damages of both psammophytes and improves their drought tolerance and acclimation to soil drought conditions in the future. Additionally, the photosynthesis decreased more slowly in the subsequent drought cycles than in the first cycle, allowing both psammophytes to maximize assimilation in response to repeated soil drought conditions. Thus, both psammophytes acclimatize themselves to repeated soil drought.

Proline Accumulation in Leaves of Periploca sepium via Both Biosynthesis Up-Regulation and Transport during Recovery from Severe Drought

“…Under mild drought conditions, similar to many other reports [31], [32], Pro biosynthesis was up-regulated under drought and down-regulated during recovery period (Figure 2). As Pro did not accumulate highly enough to explain its contribution to osmotic adjustment, Pro mainly functions as a stabilizer of subcellular structures or a redox-buffering agent [10].…”

Do successive climate extremes weaken the resistance of plant communities? An experimental study using plant assemblages

“…For example, pre-treatment with heat often brings greater tolerance to subsequent heat (Wahid et al, 2007;Xu et al, 2006). Several plant species have also been found to acclimate to multiple drought cycles (Gallé et al, 2011;Luo et al, 2011) even when the aboveground parts were harvested before the following drought period (Walter et al, 2011). Drought preconditioning is sometimes applied to improve the drought resistance of seedlings or young plants used for restoration or plantations (Guarnaschelli et al, 2006;Ruiz-Sánchez et al, 2000;Vilagrosa et al, 2003;Villar-Salvador et al, 2004).…”

Differential growth, physiological and biochemical responses of niger (Guizotia abyssinica Cass.) cultivars to water-deficit (drought) stress

“…5a-c). Similarly, many workers have reported the increased accumulation of osmolytes (proline, glycine betaine and soluble sugars) in tolerant cultivars in comparison to sensitive cultivars under waterdeficit conditions and suggested its co-ordinated action with the presence of superior osmo-protectant mechanism in tolerant cultivars (Bacelar et al 2009;Chaitanya et al 2010;Srivastava et al 2010;Koskeroglu and Tuna 2010;Luo et al 2011;Zhang et al 2011).…”