Developmental and biochemical analyses of in vitro drought stress response in ornamental European Bluestar (Amsonia orientalis Decne.)

Abstract

This study aimed to investigate the effects of drought stress on Amsonia orientalis, an endangered ornamental plant with a limited natural distribution in Europe. Effects of polyethylene glycol (PEG)-mediated drought stress (-0.15, -0.49, -1.03 and -1.76 MPa osmotic potentials) were tested on in vitro cultures. In general, root lengths and numbers, total protein, chlorophyll a and carotenoid contents were negatively influenced at elevated levels of the stress factor. The successive decrease in the tested osmotic potentials resulted in gradually higher H2O2, malondialdehyde (MDA) and proline contents. Activities of the antioxidant enzymes, peroxidase (POD) and catalase (CAT), were found to be enhanced in response to the decreasing osmotic potential tested, whereas increased superoxide dismutase (SOD) activity was observed at the -0.15 MPa osmotic potential. Strong activation of POD enzymes under drought stress suggests that POD enzymes might have a major role in regulating the H2O2 content, while CAT has only a supplementary role in A. orientalis. These results indicated that although A. orientalis is susceptible to long-term drought, the species may survive during mild drought stress because the development of the plant was not totally inhibited but only limited. Nevertheless, the species should be introduced to well-irrigated lands, after evaluation of the soil’s water status, in order to ensure the continuation of its generations.

Response of Thymus lotocephalus In Vitro Cultures to Drought Stress and Role of Green Extracts in Cosmetics

“…The highest PEG concentration (7%) caused the biggest decrease in shoot length (11.5 ± 0.43 mm), which was statistically different from that of the control (48.3 ± 2.68 mm) and the PEG concentration 2% ( Table 1 ). Similar results were obtained in in vitro cultures of Thymus vulgaris [ 4 ], Thymus citriodorus [ 7 ], Salvia leriifolia [ 46 ], Stevia rebaudiana [ 3 ], and Amsonia orientalis [ 47 ], under drought stress. When plants are subjected to drought stress, the water movement through the xylem decreases, and to maintain turgor status plant cells have to reduce their osmotic potential [ 47 ].…”

“…Similar results were obtained in in vitro cultures of Thymus vulgaris [ 4 ], Thymus citriodorus [ 7 ], Salvia leriifolia [ 46 ], Stevia rebaudiana [ 3 ], and Amsonia orientalis [ 47 ], under drought stress. When plants are subjected to drought stress, the water movement through the xylem decreases, and to maintain turgor status plant cells have to reduce their osmotic potential [ 47 ]. The decrease in shoot length could be explained by the restricted water absorption and the turgescence pressure for cell enlargement, which disrupt cell division and elongation [ 46 ].…”

“…The highest contents were observed in the control, and the increasing drought stress progressively reduced total chlorophylls and carotenoid contents, with 7% PEG inducing a reduction of 51.35% and 56.25%, respectively. A decline in photosynthetic pigment levels under PEG stress was also observed in other species [ 4 , 46 , 47 , 51 , 53 ]. MeJA caused a reversion of the 7% PEG effects on the levels of total chlorophylls (from 0.38 ± 0.02 to 0.51 ± 0.03 mg/g FW ).…”

Effects of zinc and molybdenum on European Bluestar (Amsonia orientalis): An in vitro study

“…Increasing POD activity was also reported in Glycine max (50) and Triticum aestivum (51) after Mo and Zn treatments, respectively. In a recent study on A. orientalis, it was shown that elevated POD activity and nearly unchanged CAT activity catalyzed the transformation of H 2 O 2 to H 2 O and protected the plant against drought stress (5). The increases in POD and CAT activities after Zn/Mo exposure were more pronounced than was found following salt and drought stresses in A. orientalis (4).…”

“…The decrease in its habitat may be related to anthropogenic and/or environmental abiotic factors. To investigate the effects of salt and drought stress on the growth and physiology of A. orientalis, several studies have been conducted (4,5). However, the effects of heavy metal contamination, which is a major global environmental problem, on A.…”