β-Glucosidases are diverse group of enzymes with great functional importance to biological systems. These are grouped in multiple glycoside hydrolase families based on their catalytic and sequence characteristics. Most studies carried out on β-glucosidases are focused on their industrial applications rather than their endogenous function in the target organisms. β-Glucosidases performed many functions in bacteria as they are components of large complexes called cellulosomes and are responsible for the hydrolysis of short chain oligosaccharides and cellobiose. In plants, β-glucosidases are involved in processes like formation of required intermediates for cell wall lignification, degradation of endosperm’s cell wall during germination and in plant defense against biotic stresses. Mammalian β-glucosidases are thought to play roles in metabolism of glycolipids and dietary glucosides, and signaling functions. These enzymes have diverse biotechnological applications in food, surfactant, biofuel, and agricultural industries. The search for novel and improved β-glucosidase is still continued to fulfills demand of an industrially suitable enzyme. In this review, a comprehensive overview on detailed functional roles of β-glucosidases in different organisms, their industrial applications, and recent cloning and expression studies with biochemical characterization of such enzymes is presented for the better understanding and efficient use of diverse β-glucosidases.

Stevia is a natural source of commercially important steviol glycosides (SGs), which share biosynthesis route with gibberellic acids (GAs) through plastidal MEP and cytosolic MVA pathways. Ontogeny-dependent deviation in SGs biosynthesis is one of the key factor for global cultivation of Stevia, has not been studied at transcriptional level. To dissect underlying molecular mechanism, we followed a global transcriptome sequencing approach and generated more than 100 million reads. Annotation of 41,262 de novo assembled transcripts identified all the genes required for SGs and GAs biosynthesis. Differential gene expression and quantitative analysis of important pathway genes (DXS, HMGR, KA13H) and gene regulators (WRKY, MYB, NAC TFs) indicated developmental phase dependent utilization of metabolic flux between SGs and GAs synthesis. Further, identification of 124 CYPs and 45 UGTs enrich the genomic resources, and their PPI network analysis with SGs/GAs biosynthesis proteins identifies putative candidates involved in metabolic changes, as supported by their developmental phase-dependent expression. These putative targets can expedite molecular breeding and genetic engineering efforts to enhance SGs content, biomass and yield. Futuristically, the generated dataset will be a useful resource for development of functional molecular markers for diversity characterization, genome mapping and evolutionary studies in Stevia.

Trillium govanianum, an endangered medicinal herb native to the Himalaya, is less studied at the molecular level due to the non-availability of genomic resources. To facilitate the basic understanding of the key genes and regulatory mechanism of pharmaceutically important biosynthesis pathways, first spatial transcriptome sequencing of T. govanianum was performed. 151,622,376 (~11.5 Gb) high quality reads obtained using paired-end Illumina sequencing were de novo assembled into 69,174 transcripts. Functional annotation with multiple public databases identified array of genes involved in steroidal saponin biosynthesis and other secondary metabolite pathways including brassinosteroid, carotenoid, diterpenoid, flavonoid, phenylpropanoid, steroid and terpenoid backbone biosynthesis, and important TF families (bHLH, MYB related, NAC, FAR1, bZIP, B3 and WRKY). Differentially expressed large number of transcripts, together with CYPs and UGTs suggests involvement of these candidates in tissue specific expression. Combined transcriptome and expression analysis revealed that leaf and fruit tissues are the main site of steroidal saponin biosynthesis. In conclusion, comprehensive genomic dataset created in the current study will serve as a resource for identification of potential candidates for genetic manipulation of targeted bioactive metabolites and also contribute for development of functionally relevant molecular marker resource to expedite molecular breeding and conservation efforts in T. govanianum.

Tea is popular health beverage consumed by millions of people worldwide. Drought is among the acute abiotic stress severely affecting tea cultivation, globally. In current study, transcriptome sequencing of four diverse tea genotypes with inherent contrasting genetic response to drought (tolerant & sensitive) generated more than 140 million reads.De novoand reference-based assembly and functional annotation of 67,093 transcripts with multifarious public protein databases yielded 54,484 (78.2%) transcripts with significant enrichment of GO and KEGG drought responsive pathways in tolerant genotypes. Comparative DGE and qRT analysis revealed key role of ABA dependent & independent pathways, potassium & ABC membrane transporters (AtABCG22,AtABCG11,AtABCC5 &AtABCC4) and antioxidant defence system against oxidative stress in tolerant genotypes, while seems to be failed in sensitive genotypes. Additionally, highly expressed UPL3HECT E3 ligases and RING E3 ligases possibly enhance drought tolerance by actively regulating functional modification of stress related genes. Further, ascertainment of, 80803 high quality putative SNPs with functional validation of key non-synonymous SNPs suggested their implications for developing high-throughput genotyping platform in tea. Futuristically, functionally relevant genomic resources can be potentially utilized for gene discovery, genetic engineering and marker-assisted genetic improvement for better yield and quality in tea under drought conditions.