Improving water deficit tolerance of Salvia officinalis L. using putrescine

Harvest time explains substantially more variance in yield, essential oil and quality performances of Salvia officinalis than irrigation and putrescine application

Elicitors, irrigation regimes and harvest times influence the content, yield and compound of the essential oil (EO) in Salvia officinalis (sage), through changes in biomass dynamics and biosynthetic pathways. A two-year field experiment was conducted to determine if foliar application of putrescine under optimum and deficit stress conditions would favorably affect EO yield, content and profile of sage harvested in spring and summer. The response of dry weight, EO yield and content, myrcene and borneol concentrations to irrigation regime and putrescine concentration can be expressed by a quadratic model. The maximum dry weight (182.63 g m-2) and EO yield (1.68 g m-2) were predicted under irrigation regimes of 9.06% and 27.75% available soil water depletion (ASWD), respectively. The highest EO content (1.05%) was predicted under 3.04 mM of putrescine. Based on results obtained from GC/MS analyses, 25 compounds (mostly monoterpenes) were identified in the EO of sage. Among EO compounds, α-thujone (54.08%), 1, 8-cineole (17.87%), pinocarvone (14.30%), β-thujone (7.97%) and camphor (8.76%) in turn were the most abundant. The concentration of myrcene was higher in spring than summer under the irrigation regimes of 60% and 80% ASWD. The myrcene concentration reached its maximum (4.53%) under the irrigation regime of 86.5% ASWD. The irrigation regimes of 48.03% and 45.6% ASWD caused the highest borneol concentrations of 1.47% and 1.41% by application of 1.5 mM and 2.25 mM putrescine, respectively. All treatments tested on sage, particularly harvest time, can play an important role in the improvement of EO quality and quantity. Averaged over both years, the irrigation regime of nearly 30% ASWD resulted in the highest EO yield harvested with greater quantity and better quality in summer. The EO content and quality changed slightly with the application of putrescine, without significant effect on yield.

Effect of Phytosynthesized Selenium and Cerium Oxide Nanoparticles on Wheat (Triticum aestivum L.) against Stripe Rust Disease

In this study, selenium nanoparticles (SeNPs) and cerium oxide nanoparticles (CeONPs) were synthesized by using the extract of Melia azedarach leaves, and Acorus calamusas rhizomes, respectively, and investigated for the biological and sustainable control of yellow, or stripe rust, disease in wheat. The green synthesized NPs were characterized by UV-Visible spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD). The SeNPs and CeONPs, with different concentrations (i.e., 10, 20, 30, and 40 mg/L), were exogenously applied to wheat infected with Puccinia striformis. SeNPs and CeONPs, at a concentration of 30 mg/L, were found to be the most suitable concentrations, which reduced the disease severity and enhanced the morphological (plant height, root length, shoot length, leaf length, and ear length), physiological (chlorophyll and membrane stability index), biochemical (proline, phenolics and flavonoids) and antioxidant (SOD and POD) parameters. The antioxidant activity of SeNPs and CeONPs was also measured. For this purpose, different concentrations (50, 100, 150, 200 and 400 ppm) of both SeNPs and CeONPs were used. The concentration of 400 ppm most promoted the DPPH, ABTS and reducing power activity of both SeNPs and CeONPs. This study is considered the first biocompatible approach to evaluate the potential of green synthesized SeNPs and CeONPs to improve the health of yellow, or stripe rust, infected wheat plants and to provide an effective management strategy to inhibit the growth of Puccinia striformis.

Putrescine: A Key Metabolite Involved in Plant Development, Tolerance and Resistance Responses to Stress

Putrescine (Put) is the starting point of the polyamines (PAs) pathway and the most common PA in higher plants. It is synthesized by two main pathways (from ornithine and arginine), but recently a third pathway from citrulline was reported in sesame plants. There is strong evidence that Put may play a crucial role not only in plant growth and development but also in the tolerance responses to the major stresses affecting crop production. The main strategies to investigate the involvement of PA in plant systems are based on the application of competitive inhibitors, exogenous PAs treatments, and the most efficient approaches based on mutant and transgenic plants. Thus, in this article, the recent advances in understanding the role of this metabolite in plant growth promotion and protection against abiotic and biotic stresses will be discussed to provide an overview for future research.