The effect of colloidal silver nanoparticles on the level of lignification and hyperhydricity syndrome in Thymus daenensis vitro shoots: a possible involvement of bonded polyamines

Abstract

Hyperhydricity syndrome (HHS) occurs when plants are stressed resulting in sharp changes in the ethylene concentration in the in vitro culture. One of the characteristics of HHS is the reduction of cell wall lignification. The aim of this study was to examine the effects of silver nanoparticles (AgNPs) on HHS in micropropagated Thymus daenensis shoots. AgNPs (0, 1, 2.5, or 5 mg L −1 ) were mixed with Murashige and Skoog (MS) culture medium and the antioxidant response and variations in lignin content were measured on micropropagated shoots derived from seedlings cultured with AgNPs. In addition, the different forms of microshoot polyamines (PAs) were investigated through High Performance Thin Layer Chromatography (HPTLC). The results indicated that seedling pretreatment with AgNPs at concentrations of 1 and 2.5 mg L −1 led to a decrease in the activity of the microshoot antioxidant system resulting in an increase of H 2 O 2 . Furthermore, the increased lignin content in response to the 2.5 mg L −1 AgNPs treatment was accompanied by an increase in the concentration of the bonded form of putrescine (Put) and spermine (Spm). There was a direct correlation between the lignin content and the concentration of bonded PAs. We hypothesize that the higher level of bonded PAs reduced the concentration of the free forms, leading to increased lignification. This may have led to the decreased HHS observed in shoot cultures.

Effect of cytokinins on in vitro multiplication, volatiles composition and rosmarinic acid content of Thymus leucotrichus Hal. shoots

“…However, in our study, only higher TDZ supplement caused hyperhydricity. A new technique has been recently introduced to prevent hyperhydricity involving incorporating colloidal silver nanoparticles (AgNPs) into MS basal medium (Bernard et al 2015).…”

Conservation of Thymus pallidus Cosson ex Batt. by shoot tip and axillary bud in vitro culture

“…This technique facilitates the rapid establishment of a large number of mother plants with minimal impact on endangered wild plants (Abdallah et al 2017). Subsequently, several studies have focused on the in vitro propagation of different species of the genus Thymus (Bernard et al 2015;Macro-Medina and Casas 2015;Mirshekar et al 2014; and, the present study is the first to establish a micropropagation protocol for T. pallidus Coss., through the evaluation of the effect of different compositions of culture media, to determine the best ones for good growth of vitro-plants.…”

“…Actually, MS basal medium was the most used for Thymus in vitro culture (Bakhtiar et al 2014;Bernard et al 2015;Coelho et al 2012;Costa et al 2012;Hassannejad et al 2012;Macro-Medina and Casas 2015;Mendes et al 2013;Mirshekar et al 2014;, but less concentrated media were used in other studies (Fraternale et al 2003;Furmanowa and Olszowska 1992;Kirillov et al 2014;Pérez-Tortosa et al 2012;Sáez et al 1994) or MS with reduced levels of macronutrients The data represent the mean ± SE of replicates (n = 3). Values in the same rows carrying different letters are significantly different between treatments and compared by Duncan's multiple range tests at p ≤ 0.05.…”

Effect of Macronutrients, Cytokinins and Auxins, on <i>in Vitro</i> Organogenesis of <i>Thymus vulgaris</i> L.

“…Results obtained concerning the effect of macronutrients on the micropropagation of Thymus vulgaris allowed us to choose MS macronutrients for the rest of our experiments, since they ensure a good regeneration of the aerial part, especially in terms of elongation, with complete absence of hyperhydricity. [26] and for species of the genus Thymus in general [27]- [36]. However, less concentrated media were opted in some studies, namely 1/2 MS for Thymus satureioides Coss.…”