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Global agricultural systems are under unprecedented pressures due to climate change. Advanced nano-engineering can help increase crop yields while ensuring sustainability. Nanotechnology improves agricultural productivity by boosting input efficiency and reducing waste. Alkaloids as one of the numerous secondary metabolites that serve variety of cellular functions essential for physiological processes. This study tests the competence of silver nanoparticles (AgNPs) in boosting alkaloids accumulation in Catharanthus roseus suspension cultures in relation to the expression of C. roseus Mitogen Activated Protein Kinase 3 (CrMPK3) and Strictosidine Synthase (STR) genes. Five concentrations (5, 10, 15, 20 and 25 mg·L-1) of AgNPs were utilized in addition to deionized water as control. Results reflected binary positive correlations among AgNPs concentration, oxidative stress indicated with increase in hydrogen peroxide and malondialdehyde contents, activities of ascorbate peroxidase and superoxide dismutase, expression of the regulatory gene CrMPK3 and the alkaloid biosynthetic gene STR as well as alkaloids accumulation. These correlations add to the growing evidence that AgNPs can trigger the accumulation of alkaloids in plant cells through a signaling pathway that involves hydrogen peroxide and MAPKs, leading to up-regulation of the biosynthetic genes, including STR gene.
RESUMO
BACKGROUND: Sweet sorghum is an emerging biofuel candidate crop with multiple benefits as a source of biomass energy. Increase of biomass and sugar productivity and quality is a central goal in its improvement. Target region amplified polymorphism (TRAP) is a polymerase chain reaction (PCR) based functional marker system that can detect genetic diversity in the functional region of target genes. Thirty sweet sorghum genotypes were used to study the potential of 24 pairs of TRAP marker system in assessing genetic diversity with regard to three lignin and three sucrose biosynthesis genes. RESULTS: A total of 1638 bands were produced out of which 1161 (70.88%) were polymorphic at least at one locus. The average polymorphic information content (PIC), resolving power (RP), marker index (MI), Shannon's diversity index (H), and gene diversity values were 0.32, 8.86, 1.74, 3.25, and 0.329, respectively. Analysis of molecular variance (AMOVA) revealed a highly significant genetic variation both within and among accessions studied (P = 0.01). However, the variation within the population was higher than among the populations (accessions). Bootstrap analysis showed that the number of loci amplified using this marker system is sufficient to estimate the available genetic diversity. The thirty genotypes were categorized into five clusters using a similarity matrix at 0.72 coefficient of similarity. The genotypes were also grouped mostly according to their geographic origin where the Ethiopian and Egyptian genotypes tend to fall in specific clusters. Moreover, the genotypes reflected the same pattern of distribution when ordinated using principal coordinate analysis. CONCLUSIONS: In conclusion, TRAP marker can be used as a powerful tool to study genetic diversity in sweet sorghum.
