Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene

Abstract

a b s t r a c tRecently our findings have shown that the integration of the gene coding for the rat gluco-corticoid receptor (GR receptor) in Nicotiana langsdorffii plants induced morphophysiological effects in transgenic plants through the modification of their hormonal pattern. Phytohormones play a key role in plant responses to many different biotic and abiotic stresses since a modified hormonal profile up-regulates the activation of secondary metabolites involved in the response to stress. In this work transgenic GR plants and isogenic wild type genotypes were exposed to metal stress by treating them with 30 ppm cadmium(II) or 50 ppm chromium(VI). Hormonal patterns along with changes in key response related metabolites were then monitored and compared. Heavy metal up-take was found to be lower in the GR plants. The transgenic plants exhibited higher values of S-abscisic acid (S-ABA) and 3-indole acetic acid (IAA), salicylic acid and total polyphenols, chlorogenic acid and antiradical activity, compared to the untransformed wild type plants. Both Cd and Cr treatments led to an increase in hormone concentrations and secondary metabolites only in wild type plants. Analysis of the results suggests that the stress responses due to changes in the plant's hormonal system may derive from the interaction between the GR receptor and phytosteroids, which are known to play a key role in plant physiology and development.

Meloydogine incognita (Nematoda) reproduction affected by plants overexpressing a steroid inducible gene-expression system

“…In fact, GUS fluorescence signals were gained only at higher doses of exogenous steroids. On the other hand, altered contents of several phyto-hormones have been already quantitatively reported by other authors in different Nicotiana species expressing exactly the same GR sequence [33,34]. Moreover, this data reported also a full restoration of the roots growth in transGR þ by the addition of high doses of auxin (NAA), thus also revealing a possible auxins and phytosteroids interconnection.…”

“…The dwarf phenotype affecting transGR þ resembled mostly those associated to the hormonal imbalance reported by others [19,34,43,44] or due to overexpression of certain regulatory domains [19,20,45]. The hypothesis of a sort of hormonal disturbance generated by transgene overexpression was tested by assaying the sensitivities of transGR þ to exogenously applied phyto-hormones.…”

“…Successively, other authors have hormonally characterized some transgenic Nicotiana spp. by gas chromatography and mass spectrometry [33,34]. Here in it is shown that the tobacco plants overexpressing a GR-system appear morphologically affected at hypocotyls and roots development, either in vitro or in vivo.…”

Metabolomic analysis of wild and transgenic Nicotiana langsdorffii plants exposed to abiotic stresses: unraveling metabolic responses

“…The procedure for obtaining these genetic modifications is extensively described by Giannarelli et al [7] and Fuoco et al [13]. The expression of the transgenes was screened, as previously described [13].…”

“…The Nicotiana genus (family of Solanaceae) includes small, well-characterized plants, traditionally used as biological models for genetic and physiological studies [12]; the genetic rol C and GR modifications of N. Langsdorffii and Nicotiana glauca plants were previously investigated, yielding interesting results for the production of plants resistant to different stresses [7,11,13].…”