Overexpression of Osmyb4 enhances compatible solute accumulation and increases stress tolerance of Arabidopsis thaliana

Abstract

In this paper, we report the metabolic and molecular changes in response to cold and drought induced in Osmyb4 transgenic Arabidopsis thaliana compared with the wildtype (WT). The rice Osmyb4 gene codes for a transcription factor (Myb4) induced by cold treatment and, in Arabidopsis transgenic plants, improves cold and freezing tolerance [Vannini C, Locatelli F, Bracale M, Magnani E, Marsoni M, Osnato M, Mattana M, Baldoni E, Coraggio I (2004) Plant J 37: 115-127].Here, we report the ability of Myb4 to induce also drought tolerance in Arabidopsis transgenic plants. By the use of nuclear magnetic resonance (NMR) and enzymatic assays, we showed that several compatible solutes (glucose, fructose, sucrose, proline, glycine betaine and sinapoyl malate) accumulate in higher amount in Osmyb4-overexpressing plants with respect to the WT, both under normal and stress conditions. Considering proline, we also found that in transgenic plants the levels of the mRNAs coding for D 1 -pyrroline-5-carboxylate synthase (EC not assigned) and for D 1 -pyrroline-5-carboxylate dehydrogenase (EC 1.5.1.12) were higher and lower, respectively. The constitutive activation of several stress-inducible pathways and different kinetics in the accumulation of several metabolites, in Myb4 transgenic plants, may represent an advantage to prepare plants to face the stress condition. Moreover, these results taken together suggest that Myb4 integrates the activation of multiple components of stress response.Abbreviations -LC-NMR, liquid chromatography-NMR; NMR, nuclear magnetic resonance; PAL, phenylalanine ammonia lyase; P5CDH, D 1 -pyrroline-5-carboxylate dehydrogenase; P5CS, D 1 -pyrroline-5-carboxylate synthase.

Plant Metabolomics: A Characterisation of Plant Responses to Abiotic Stresses

“…Moreover, the Osmyb4-overexpressing plants showed an improved tolerance phenotype towards drought stress (Pasquali et al, 2008). A common characteristic displayed by all of the Myb4-transgenic plants under cold treatment was the increase in the proline content, whereas wt plants showed an increase in free amino acids (Laura et al, 2010;Mattana et al, 2005a;Pasquali et al, 2008). This result underlined the importance of proline accumulation during the stress, in agreement with the several roles proposed for this amino acid during abiotic stress (Verbruggen & Hermans, 2008).…”

“…They correlated the better tolerance of transgenic plants to a higher content of several metabolites (proline, sucrose, glucose, fructose, glycine betaine, alanine and sinapoyl malate) that were present in the transgenics prior to the stress treatment and that may prepare plants to face the stress. Moreover, during cold treatment, the degree of tolerance of the transformed plants further increased; the amount of the abovementioned metabolites raised in both wt and transgenic plants, but it was always higher in the transgenic lines than in wt during the time course of the experiment (Mattana et al, 2005a). Furthermore, the increased metabolic contents in transformed plants were consistent with the global changes observed in the mRNA population (Mattana et al, 2005a;Vannini et al, 2004Vannini et al, , 2006.…”

“…Moreover, during cold treatment, the degree of tolerance of the transformed plants further increased; the amount of the abovementioned metabolites raised in both wt and transgenic plants, but it was always higher in the transgenic lines than in wt during the time course of the experiment (Mattana et al, 2005a). Furthermore, the increased metabolic contents in transformed plants were consistent with the global changes observed in the mRNA population (Mattana et al, 2005a;Vannini et al, 2004Vannini et al, , 2006. Kaplan et al (2004), in a time course experiment, found that the amount of 311 out of the 497 low-M r polar compounds that were detected was affected by cold exposure.…”

“…The non-acclimated OsMyb4-transgenic plants exhibited a degree of tolerance to both chilling and freezing comparable to that developed by wt plants after cold acclimation. Subsequently, through both targeted and profiling analyses, Mattana et al (2005a) compared the changes in the metabolic content of wt and OsMyb4-transgenic plants during a ten-day-long cold experiment. They correlated the better tolerance of transgenic plants to a higher content of several metabolites (proline, sucrose, glucose, fructose, glycine betaine, alanine and sinapoyl malate) that were present in the transgenics prior to the stress treatment and that may prepare plants to face the stress.…”

Responses of rice to Rhizoctonia solani and its toxic metabolite in relation to expression of Osmyb4 transcription factor

“…Homologous as well as heterologous overex-pression of osmyb4 in monocot and dicot plants have been reported to improve stress tolerance through direct or indirect activation/repression of several downstream genes. This includes expression in crops and plants like rice (Park et al 2010), barley (Soltesz et al 2012), arabidopsis (Vannini et al 2004(Vannini et al , 2006Mattana et al 2005), tomato (Vannini et al 2007), apple (Pasquali et al 2008), and osteospermum ecklonis (Laura et al 2010). Docimo et al (2013) performed an ectopic expression of osmyb4 in tobacco and Salvia sclarea plants to produce specific bioactive compounds, the objective of which was different from the aforesaid studies on other plants.…”