Role of Secondary Metabolites of Medicago sativa in Antiviral Management and Biofertilizer Efficacy

Abstract

Medicago sativa commonly known as alfalfa, is a highly cultivated forage crop that produces many secondary metabolites (SMs) such as saponins, alkaloids and phenolic compounds. These metabolites play a fundamental role in plant defense mechanisms against biotic stresses, particularly viral infections. Alfalfa is vulnerable to various DNA and RNA viruses that compromise its production. SMs act as an antiviral agent by preventing viral entry, prohibiting their replication and movement in plant cells. These also improve plant's immunity and confer systemic acquired resistance. The biosynthesis of SMs in alfalfa is controlled by several metabolic pathways and transcription factors such as WRKY, MYB, bHLH, bZIP, AP2/ERF, and NAC. Additionally, SMs enhance the efficacy of biofertilizers by developing favorable microbial environment within the rhizosphere. Metabolic engineering techniques such as overexpression of targeted pathways, prevention of rate-limiting steps, and hindering competing pathways can optimize the production and efficiency of these SMs. Research should focus on exploiting the potential of SMs in sustainable agriculture to boost crop yield, resilience and reduce reliance on chemical-based fertilizers.