Effect of cobalt nanoparticles and cobalt ions on alkaloids production and expression of CrMPK3 gene in Catharanthus roseus suspension cultures

Abstract

The capabilities of cobalt ions (Co 2+) and cobalt nanoparticles (CoNPs) in enhancing alkaloids accumulation in Catharanthus roseus suspension cultures were evaluated in relation to the expression of CrMPK3 gene. Four concentrations (5, 10, 15 and 20 mg/L) of each cobalt form were utilized in addition to control. Both forms induced oxidative stress that was more pronounced for Co 2+ treatments. A positive correlation was observed between cobalt concentration and expression of CrMPK3 gene. However, a characteristic temporal expression profile was recorded for each cobalt form. Also, positive correlations were detected between both cobalt concentration and expression of CrMPK3 gene on one hand and the activities of antioxidant enzymes (SOD and APX) and alkaloids content on the other hand. Such correlations suggest CrMPK3 gene as a common player in cobalt-induced stress signaling; regardless of cobalt form. Results revealed the higher capability of Co 2+ , compared with CoNPs, in enhancing alkaloids accumulation. However, results supported CoNPs as a novel tool in manipulating cobaltinduced alkaloids production in C. roseus.

Effects of cobalt ions and cobalt nanoparticles on transient expression of gus gene in catharanthus roseus suspension cultures

“…Such an explanation may be logical observing the slower and smaller enhancements in the expression of plant defense genes in presence of CoNPs, compared with expression levels in presence of cobalt ions. The attenuated defense response in C. roseus suspension cultures following exposure to CoNPs, compared with cobalt ion treatments was documented in our previous publication Fouad and Hafez (2018a) and ascribed to PVP that may reduce Co2 + leaching from CoNPs. Similar effects for PVP were recorded with silver nanoparticles (Fouad & Hafez, 2018;Nymark et al, 2013).…”

“…CoNPs employed in this study were provided from Nanotech, Cairo, Egypt, as polyvinylpyrrolidone (PVP)coated particles suspended in deionized water (DW). As confirmed with aid of the transmission electron microscopy (TEM) in our previous work (Fouad & Hafez, 2018a), particles were almost spherical with an average diameter of 20-50 nm. A stock solution (1 g/L) in DW was diluted and sonicated at 100 W and 30 kHz for 30 min to prepare experimental concentrations just before use.…”

“…However, the utilization of such heavy metal should be optimized to reach the desired effects without oxidative stress symptoms associated with phytotoxic doses. Besides concentration and treatment duration, the unique characteristics of substances at the nano-scale provide a novel tool for dose optimization (Fouad & Hafez, 2018a). Little attention is paid to the applications of cobalt nanoparticles in biotechnology (Fouad & Hafez, 2018a;Ghasemi et al, 2015).…”

Effect of Salt and Osmotic Stresses on the Activity of Some Antioxidant Enzymes and Biochemical Traits in Catharanthus roseus

“…These characteristics make the alkaloids of a great importance goal for production by biotechnological tools. C. roseus plants are repeatedly exposed to abiotic stresses such as low temperatures, heat, salinity, water deficit, oxidative stress, and nano-metal toxicity and UV radiation (9)(10)(11), which produce free radicals like Reactive Oxygen Species (ROS) in plant tissues, which are toxic for membrane system and biological macromolecules. Water and salt stress are major production-limiting factors of agricultural crops throughout the world, which often lead to a remarkable decline in plants growth and productivity (12).…”

“…From the technological point of view, it was revealed that C. roseus plant cells can be successfully cultured to produce the required alkaloids in quite enormous amounts (22). Large scale production could be achieved via either manipulation of in vitro cultures, to improve the selection efficiency and development of high producing cell lines and optimization of culture conditions (23), or through genetic alteration, which includes the overexpression of some step-limiting enzymes in alkaloid biosynthesis pathways (11). Several results demonstrated that inducing agents (NaCl and PEG-6000), have fruitfully been applied to enhance alkaloid production.…”