Acclimatization of micropropagated plantlets induces an antioxidative burst: a case study with Ulmus minor Mill.

Abstract

In this article, the effects of increased light intensities on antioxidant metabolism during ex vitro establishment of Ulmus minor micropropagated plants are investigated. Three month old in vitro plants were acclimatized to ex vitro conditions in a climate chamber with two different light intensities, 200 µmol m -2 s -1 (high light, HL) and 100 µmol m -2 s -1 (low light, LL) during 40 days. Immediately after ex vitro transfer, the increase of both malondialdehyde (MDA) and electrolyte leakage in persistent leaves is indicative of oxidative stress. As the acclimatization continues, an upregulation of the superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) enzyme activities were also observed. Simultaneously, MDA content and membrane permeability stabilized, suggesting that the antioxidant enzymes decrease the deleterious effects of reactive oxygen species (ROS) generation. Unexpectedly, newly formed leaves presented a different pattern of antioxidative profile, with high levels of MDA and membrane leakage and low antioxidant enzyme activity. Despite these differences, both leaf types looked healthy (e.g. greenish, with no necrotic spots) during the whole acclimatization period. The results indicate that micropropagated U. minor plantlets develop an antioxidant enzyme system after ex vitro transfer and that, in general, LL treatment leads to lower oxidative stress. Moreover, new leaves tolerate higher levels of ROS without the need to activate the antioxidative pathway, which suggests that the environment at which leaves are exposed during its formation determinate their ability to tolerate ROS.

Physiological and biochemical parameters influencing ex vitro establishment of the in vitro regenerants of Albizia lebbeck (L.) Benth.: an important soil reclaiming plantation tree

“…Likewise, transfer of A. lebbeck plantlets under threefold (150 PPFD) light intensity than in vitro condition (50 PPFD) favours proper acclimatization of the plantlets as proved by the enhanced levels of photosynthetic parameters. Similar results have been reported in Gardenia jasmiinoides by Serret et al (2001) and Ulmus minor by Dias et al (2013). While, an increase in carotenoids level particularly signifies that plants sustained the light stress as play a key role in protecting of chlorophyll pigments under stress conditions (Ali et al 2005).…”

Exogenous salicylic acid alleviates cold damage by regulating antioxidative system in two barley (Hordeum vulgareL.) cultivars

“…Certain researchers also reported that cold stress increased the generation of ROS, including H 2 O 2 in plants, and as a result of this the MDA content could be also increased (Senaratna et al 2000;Kang et al 2003). In addition, it has been suggested that this effect of cold stress can disrupt the permeability of the cell membrane structure of the plant (Dias et al 2011). In the plants applied SA and then exposed to cold (SA + cold treatment), the MDA content was determined significantly to be decreased at all days (10, 17, 24 and 31) in comparison to respective cold values (Figure 1).…”

“…Because, similar to other stresses, reactive oxygen species (ROS) such as superoxide anion (O − 2 ), CONTACT Salih Mutlu salihmutlu@yahoo.com H 2 O 2 and hydroxyl radicals ( · OH) are produced during response to cold stress (Mutlu et al 2009a(Mutlu et al , 2009bHu et al 2010). Toxic levels of ROS can impair membrane permeability (Dias et al 2011) by inducing lipid peroxidation (Mutlu et al 2011;Esim et al 2014), cause damage to DNA and proteins (Bertrand et al 2011;Kekec et al 2013) and ultimately lead to programmed cell death. These symptoms during cold stress have been evaluated as oxidative damage (Wang et al 2009a).…”

“…Recently, some researchers carried out on winter wheat (Tasgin et al 2006) and watermelon (Yang et al 2008) demonstrated that exogenous SA treatment could be involved in cold tolerance by regulating the activities of antioxidant enzymes. The action mode of exogenous SA on the antioxidative system during response to cold and the time-dependent effect of SA when it was applied to a plant before cold exposure are still unclear although recent studies provide intensive data about the role of exogenous SA in the regulation of environmental stress response, including cold stress (Korkmaz, 2005;Shi et al 2006;Guo et al 2009;Mutlu et al 2009a;Xia et al 2009;Hu et al 2010;Dias et al 2011;Zhang et al 2011b;Luo et al 2012). On the other hand, there are inadequate and conflicting results in the literature about the effects of exogenous SA applied to a plant before cold stress treatment on the enzymatic antioxidative system.…”

Review of Literature

“…Under high irradiance, significant changes in the activity of the antioxidant enzymatic system were observed in micropropagated plants of Calathea (Dias et al 2011). …”