plants possessing multiple stress tolerance. We examined here the expression and function of DcHsp17.7 under oxidative and osmotic stress conditions, which are abiotic stresses that frequently accompany heat stress ( Vandenbroucke et al., 2008 ). In
Sameh Sassi-Aydi, Samir Aydi, and Chedly Abdelly
). Several authors have addressed the inhibitory effect of osmotic stress on root nodule activity in legumes ( King and Purcell, 2001 , 2005 ; Marino et al., 2006 ; Serraj and Sinclair, 1997 ) including common bean ( Phaseolus vulgaris L.) ( Sassi et al
Tingting Sun, Tingting Pei, Zhijun Zhang, Mingjun Li, Linlin Huang, Cuiying Li, Xueyan Shi, Minghui Zhan, Xiaoyu Cao, Fengwang Ma, and Changhai Liu
). This indicates that PHTs are involved not only in low P but also in drought resistance. Polyethylene glycol 6000 (PEG6000) is frequently used in experiments to simulate osmotic stress ( Bhargava and Paranjpe, 2004 ; Radhouane, 2007 ). With a
Takashi Ikeda, Yukihiro Fujime, Satoshi Terabayashi, and Shuichi Date
Garlic (Allium sativum L.) calli in vitro were evaluated over a range of salt concentrations and by adding mannitol to culture medium with reduced salt to provide equivalent osmoticum. The water potential of the medium ranged from -0.27 to -0.73 MPa under the various salt and osmotic stress conditions. The percent increase in calli was highest in standard Murashige & Skoog (MS) medium and was reduced when MS salts were reduced but the water potential of medium was adjusted to that of standard MS medium by addition of mannitol. The water potential of callus tissue was similar to that of tissue culture media over a 20-fold range (10% to 200%) of MS concentrations. Turgor of callus tissue was not influenced by any stress conditions. These results indicate that the optimum concentration of salt and water status of medium for formation of garlic calli was provided by standard MS medium.
Suejin Park, Youyoun Moon, and Nicole L. Waterland
al., 2003 ; Zhang et al., 2006 ). However, a pre-exposure to osmotic stress has not been studied for enhancing tolerance to water deficit stress. Calcium is well-known as a secondary messenger involved in various physiological and biochemical
William L. Berndt
‘SeaDwarf’, which could negatively affect important turf characteristics such as rate of spread hence recuperative capacity. The effect salinity had on quality parameters may have been related to development of osmotic stress producing physiological
William R. Graves and Lorna C. Wilkins
Growth of honey locust (Gleditsia triacanthos var. inermis Willd.) seedlings was studied during exposure to reduced osmotic potential (ψπ) and high temperature in the root zone. Half-sib plants were cultured in solution. Root-zone temperature was increased from ambient (23C) to 35C for 0, 6, 12, or 24 hours·day -l. Within each temperature treatment, solution ψπ of -0.05, – 0.10, and – 0.20 MPa were maintained by additions of polyethylene glycol (PEG) 8000. Root and shoot dry weights decreased with increasing exposure to 35C among seedlings in -0.05-MPa solution and decreased for seedlings in - 0.10- and - 0.20-MPa solutions in all temperature regimes. Growth of epicotyls displayed similar trends, but epicotyls of plants in -0.20-MPa solution were longest with 6 hours·day-l at 35C. Significant interactions between effects of temperature and osmotic regimes indicated that water-stressed honey locust seedlings are relatively insensitive to elevated root-zone temperatures. However, related studies showed that PEG caused reductions in growth that could not be explained by decreases in ψπ and suggested that responses of honey locust to PEG differed from those when drought was imposed by withholding irrigation in an aggregate medium.
Rida Shibli, L. Art Spomer, and Mary Ann Lila Smith
Osmotic adjustment in response to decreasing media water availability was observed for in vitro Chrysanthemum morifolium Ramat. cultivars Bright Golden Anne, Deep Luv, and Lucido. Water stress was induced by increasing sorbitol (0, 0.1, 0.2, 0.3, 0.4 M), mannitol (0, 0.1, 0.2, 0.3, 0.4 M), and sucrose (30, 45, 60, 75, 90 g·l-1) concentrations in modified MS media (2 mg·l-1 BA and 0.1 mg·l-1 NAA). Osmotic adjustment was evidenced by a significant reduction in measured cell sap osmotic potential (R2 = 0.78, 0.96, 0.91 for sucrose, sorbitol, and mannitol respectively) in all cultivars. Shoot length, weighted density (apparent mass), and proliferation were significantly reduced by sorbitol and mannitol treatments. Sucrose reduced shoot proliferation, increased length, and had an inconsistent effect on weighted density. Cultures grown on media without hormones showed tremendous increase in root number up to 60 g·l-1 sucrose. Sorbitol had a negligible effect on rooting at 0.1 M but no roots developed at higher sorbitol concentrations or in any mannitol treatments. Plants transferred to a non-water-stress media after they had experienced in vitro water stress exhibited no change in osmotic properties from the stress treatments.
W. Roland Leatherwood, D. Mason Pharr, Lisa O. Dean, and John D. Williamson
mechanisms to protect against specific ion effects and osmotic stresses imposed by saline soils. These mechanisms include increases in proteins involved in water transport (i.e., aquaporins), ion sequestration and secretion ( Baiges et al., 2002 ; Figueras
Sanalkumar Krishnan and Emily B. Merewitz
stress is a combined stress since it can cause osmotic stress to plants as well as direct toxicity to plants due to Na + toxicity ( Parida and Das, 2005 ). We have evaluated salt ion concentrations, physiological responses, and hormone analysis to