Subcellular Effects of Drought Stress in Rosmarinus officinalis

Abstract

The use of Rosmarinus officinalis, and other wild plant species, in the Mediterranean area is an interesting solution in order to avoid the desertification and rapid soil erosion, because of their good resistance to environmental conditions. Previous articles have described experiments designed to determine the impact of water stress at the plant level in this species, but more knowledge is required at the subcellular and ultrastructural levels. An anatomic and ultrastructural study of the leaves was conducted on Rosmarinus officinalis plants growing under different water treatments. In the leaves of water-stressed plants, the leaf water potential and turgor decreased, and leaf osmotic potential became more negative with respect to control plants. The anatomic investigations showed that both the mesophyll intercellular spaces and the epidermal cell size were reduced significantly under the more intense drought stress conditions. At the subcellular level, chloroplasts accumulated plastoglobuli and lipid bodies, and cuticle thickness was increased under water stress. In our experiment, the anatomic and ultrastructural modifications of Rosmarinus officinalis could be considered an additional adaptation to drought stress together with physiological and biochemical modifications as antioxidant accumulation.

Anatomical adaptations of Astragalus gombiformis Pomel. under drought stress

“…It affects both elongation and expansion growth [11]. Results from this study indicate that that A. gombiformis maintain its maximum growth potential for low water deficit (10 days).…”

“…Knowledge of anatomical root modifications is essential for the explication of plants growth and hydraulic changes induced by water stress and therefore to understand the mechanisms used to confront drought conditions [11]. In our view, there is insufficient information about the changes in root anatomical as reaction to water deficit [27].…”

“…Thus, plant tissues responses to drought depend on the anatomic characteristics that regulate the transmission of the water stress effect to the cells [10]. Roots can be compared to sensors that detect water status changes in the soil through tissue dehydration and play an important role in plant resistance to water deficit [11]. However, fewer works on the anatomical modifications induced by drought stress were interested to changes in the anatomy of root and stem tissue.…”

“…Leaf tissues exposed to drought shows various responses. Thus, in many species such as, Ctenanthe setosa and Triticum aestivum, the entire lamina and mesophyll thickness were reduced under drought stress [2][3][4][5][6][7][8][9][10][11][12][13][14], while it was unaffected by water stress in salvia spendens and Glycine max [13][14][15][16]. Bussotti et al [17] found that limited soil moisture caused a major thickening of the mesophyll, especially in the leaf cuticle and spongy parenchyma of the beech plant, Fagus sylvatica.…”

“…Multiple characteristics of vascular structure have been investigated, such as modifications of the vascular bundle number and area and alteration of xylem/ phloem ratio, which are thought to be involved in the resistance of the plant to environmental stresses [18]. Several studies have shown that xylem and/or phloem vessel diameter was reduced in Ctenanthe setosa and Triticum aestivum plants subjected to drought stress [2][3][4][5][6][7][8][9][10][11][12][13][14]. Thus, xylem with narrow vessels is physiologically better protected against cavitation [19].…”