Protein mobilisation and proteolytic activities in root tubers of Asphodelus aestivus

Abstract

IntroductionKnowledge of plant traits is necessary for understanding the ecosystem responses to natural and human-induced environmental changes (Hüseyinova et al., 2013). Geophytes are important life forms among plants with specialised structures in specialised environments. Their regenerating buds are on underground storage organs, and their life cycle includes a dormant period that can extend from a few weeks to most of the year, as defined by Raunkiaer (1934). Geophytes are widespread in the Mediterranean part of the world because they can survive the summer drought (Dafni, 1996;Debussche et al., 2004).The Mediterranean geophytes are of 2 types: springflowering species that display leaves and flowers simultaneously (synanthous geophytes), and autumnalflowering species that develop flowers before leaves and leaves after the flowering (hysteranthous geophytes) (Dafni et al., 1981a). The synanthous geophytes have periods of growth, storage, flowering, and dormancy, whereas the hysteranthous geophytes go dormant after storing the food reserves such that vegetative and reproductive stages do not occur at the same time (Dafni et al., 1981a(Dafni et al., , 1981b.According to Pantis (1993), Asphodelus aestivus Brot. could be categorised as intermediate; it is synanthous, but its reproduction depends partly on stored reserves and partly on annual production. Asphodelus aestivus is one of the important geophytes growing in degraded areas of the Mediterranean environment (Pantis et al., 1994). When it covers the degraded parts of the eastern Mediterranean basin, these types of ecosystems appear like deserts, and they are called asphodel geophyte-deserts or asphodel semideserts (Naveh, 1973;Ayyad and Hilmy, 1974;Le Houerou, 1981).Asphodelus aestivus is a competitive ruderal stresstolerant strategist species, which can be found on agricultural slopes, near roads, and in calcareous soils in pastures (Pantis et al., 1994). Asphodelus aestivus is an important plant and it has become the dominant life form in some degraded Mediterranean ecosystems, including those resulting from excessive grazing and fire (Ayyad and Hilmy, 1974;Le Houerou, 1981;Pantis and Margaris, 1988). Pantis and Margaris (1988) reported that the dominance of Asphodelus aestivus in degraded areas reflects both its capacity to face the peculiarities of the Mediterranean climate and its resistance to the most common disturbances in habitat.Geophytes mainly store one or more storage compounds in their underground storage organs. They generally accumulate carbohydrates, starch, soluble sugars, glucomannans, and fructans (

Adaptive Mechanisms of Asphodelus aestivus Brot. to Withstand Drought Stress: Metabolic Constituents and Activity of Antioxidant Enzymes.

“…This may be due to growing buds and leaves which are large recipients of water during the storage period (dormancy) under drought stress (Kamenetsky and Okubo, 2013).Water content in tubers, which has been transferred to the buds can play an important role in the complete development of flowers in winter. These values were in accordance with the climatic conditions of the study area, which is characterized as a Mediterranean climate (Kirmizi et al, 2014).…”