Enhanced expression of the proline synthesis gene P5CSA in relation to seed osmopriming improvement of Brassica napus germination under salinity stress

Abstract

Osmopriming is a pre-sowing treatment that enhances germination performance and stress tolerance of germinating seeds. Brassica napus seeds showed osmopriming-improved germination and seedling growth under salinity stress. To understand the molecular and biochemical mechanisms of osmopriming-induced salinity tolerance, the accumulation of proline, gene expression and activity of enzymes involved in proline metabolism and the level of endogenous hydrogen peroxide were investigated in rape seeds during osmopriming and post-priming germination under control (H2O) and stress conditions (100 mM NaCl). The relationship between gene expression and enzymatic activity of pyrroline-5-carboxylate synthetase (P5CS), ornithine-δ-aminotransferase (OAT) and proline dehydrogenase (PDH) was determined. The improved germination performance of osmoprimed seeds was accompanied by a significant increase in proline content. The accumulation of proline during priming and post-priming germination was associated with strong up-regulation of the P5CSA gene, down-regulation of the PDH gene and accumulation of hydrogen peroxide. The up-regulated transcript level of P5CSA was consistent with the increase in P5CS activity. This study shows, for the first time, the role of priming-induced modulation of activities of particular genes and enzymes of proline turnover, and its relationship with higher content of hydrogen peroxide, in improving seed germination under salinity stress. Following initial stress-exposure, the primed seeds acquired stronger salinity stress tolerance during post-priming germination, a feature likely linked to a 'priming memory'.

Metabolic Processes During Seed Germination

“…These processes are followed by ROS (mostly H 2 O 2 ) accumulation as a result of a pronounced increase in the intracellular and extracellular production during early stages [97,98].…”

Influence of priming on Eucalyptus spp seeds' tolerance to salt stress

“…This controlled imbibition may induce mechanisms of protection and repair in seeds, resulting in a possible acclimatization that would allow seeds to tolerate a future stress (Kubala et al, 2015).…”

Arabidopsis thaliana egy2 mutants display altered expression level of genes encoding crucial photosystem II proteins

“…Isoelectrofocusing was carried out using the gel strips forming an immobilized pH gradient from 3 to 10 (Bio-Rad, Hercules, CA, USA). Strips were rehydrated overnight at room temperature and the isolectrofocusing was performed at 18°C in the Protean i12 IEF Cell (Bio-Rad, Singapore) for 90 min at 300 V, 90 min at 3500 V, 20000 VHr at 5500 V. After IEF strips were equilibrated according to Kubala et al (2015) and the separation of proteins according to their molecular mass was performed using denatured electrophoresis in the 12 % (w/v) acrylamide gels with addition of 6 M urea. After electrophoresis the gels were stained with Coomasie Brilliant Blue (CBB) G-250 and photographed with the use of ChemiDoc ™ MP Imaging System (Bio-Rad, Hercules, CA, USA).…”

“…Four images representing two independent biological replicates for each A. thaliana lines (WT, egy2-3 and egy2-5 ) were used. The differentially accumulated proteins (P < 0.05) between the WT and both mutant plant lines with a ratio at least 2.0 in absolute value of protein abundance were excised manually under sterile condition and analyzed by liquid chromatography coupled to the mass spectrometer in the Laboratory of Mass Spectrometry, Institute of Biochemistry and Biophysics, Polish Academy of Science (Warsaw, Poland) as previously described Kubala et al (2015). The raw data were processed using the Mascot Distiller software (ver.…”