Recent advancements in valorisation of Pongamia pinnata, a versatile legume tree for bioenergy and biofuel applications

Pongamia pinnata, a multipurpose leguminous tree, has risen to eminence as a sustainable supply of bioenergy and biofuel due to its oil content, tolerance to abiotic stress and marginal land adaptability. The advancements in omics technologies in the recent past have played a considerable role towards the genetic enhancement and holistic exploitation of Pongamia. Genomic and transcriptomic analyses have revealed important genes and regulatory systems in lipid metabolism, growth and responses to various stresses. Profiling of the differential gene expression under stress conditions has helped to understand the tolerance mechanisms that can be used to develop varieties that are resistant to the climatic conditions. Proteomic and metabolomic studies have resolved the functions of proteins and metabolic pathways that are keys in the biosynthesis of oil and accumulation of biomass. New epigenomic research is stressing the importance of heritable variation in the regulation of genes, as a factor leading to improved adaptability and productivity. A wide range of variability in oil content and fatty acid composition amid different accessions provides a leverage of choice and breeding of high-quality genotypes in production of biodiesel. In addition to oil extraction, deoiled seed biomass can be valorized by thermochemical processes to produce bio-oil, syngas and biochar, or by biochemical processes to produce bioethanol and other bioproducts. Such combined solutions facilitate a circular bioeconomy, where there is zero-waste usage. This review addresses the prevailing situation of omics-based developments, processing technologies and the versatility of uses of Pongamia pinnata, as a guide to future research and commercial implementation in bioenergy area.