Abstract
BackgroundMicroalgae and nanoparticles are currently considered promising tools for numerous agricultural and biotechnological applications. The green microalga Chlorella sp. MF1 and its biosynthesized silver nanoparticles (AgNPs) were used in this study as biofortification agents to enhance glucosinolate and kaempferol levels in Eruca sativa. UV–visible spectroscopy, XRD, FTIR and TEM were comprehensively used for characterizing Chlorella-based AgNPs.ResultsThe biosynthesized AgNPs were found to be spherical in shape, with size ranging from 1.45 to 5.08 nm. According to FTIR measurements, silver ions were reduced to AgNPs by functional groups such as amide, hydroxyl and carboxylate. Different experimental treatments were conducted, including either soaking seeds of E. sativa or foliar spray with various concentrations of Chlorella suspension (1, 2, 3 and 4 g L−1) and AgNPs (5, 10, 20 and 40 mg L−1). Expression levels of five key genes in the biosynthetic pathway of glucosinolates (MAM1, SUR1, MYB34 and MYB51) and kaempferol (CHS) were assessed using qRT-PCR. The results indicated an upregulation in the gene expression levels in all treatments compared to control, recording the highest level at 40 mg L−1 AgNPs and 4 g L−1Chlorella suspension. In addition, high glucosinolates and kaempferol content was detected in plants whose leaves were sprayed with AgNPs and Chlorella suspension (40 mg L−1 and 4 g L−1) based on HPLC analysis. Sequence analysis of amplified CHS fragments from E. sativa plants treated with AgNPs (40 mg L−1) showed high sequence similarity to A. thaliana CHS gene. However, there were several CHS regions with sequence polymorphism (SNPs and Indels) in foliar sprayed plants.ConclusionsResults of this study evidenced that the application of AgNPs and Chlorella suspension increased glucosinolates and kaempferol content in E. sativa through upregulation of key genes in their biosynthetic pathway.
Highlights
Microalgae and nanoparticles are currently considered promising tools for numerous agricultural and biotechnological applications
The results revealed that the key genes (CHS, Methylthioalkylmalate synthase 1 (MAM1), myeloblastosis transcription factor 34 (MYB34), myeloblastosis transcription factor 51 (MYB51) and SUPERROOT 1 (SUR1)) responded differently to various treatments of Silver nanoparticles (AgNPs) and Chlorella sp. suspension and their expression levels were significantly different from control plants, exhibiting the highest expression level of
The multiple sequence alignment (MSA) analysis indicated that there are several single nucleotide polymorphisms (SNPs) and Insertions and deletions (Indels) variations mainly in the chalcone synthase (CHS) fragment sequence of E. sativa plants sprayed with AgNPs (40 mg L−1) compared with control, AgNPs (40 mg L−1)-soaked E. sativa plants and Arabidopsis CHS gene sequences
Summary
Microalgae and nanoparticles are currently considered promising tools for numerous agricultural and biotechnological applications. MF1 and its biosynthesized silver nanoparticles (AgNPs) were used in this study as biofortification agents to enhance glucosinolate and kaempferol levels in Eruca sativa. UV–visible spectroscopy, XRD, FTIR and TEM were comprehensively used for characterizing Chlorella-based AgNPs. The interest in the bioavailability and biological effects of secondary metabolites in plants has been increased in the past two decades [78, 102]. The interest in the bioavailability and biological effects of secondary metabolites in plants has been increased in the past two decades [78, 102] These are identified by their direct free radical-scavenging and antioxidant activities.
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