Speakers

Biography

Pravesh Kundu is a Ph.D. research scholar in the lab of Dr. Gaurav Zinta at CSIR-Institute of Himalayan Bioresource Technology, Palampur, H.P

Pravesh did her B.Sc. and B.Ed. from Kurukshetra University, Haryana; and M.Sc. Botany from Punjabi University, Patiala.

Pravesh qualified national level exam CSIR-UGC-NET-JRF in 2019 with an All India Rank-94 to pursue her Ph.D. studies.

In her Ph.D., she is working on the nutritional quality of Chenopodium species and implementing tools related to metabolomics, transcriptomics, and gene functional analyses. So far, she has published one book chapter, participated in two national and international conferences, and published four research/review articles.

Specifically, she is deciphering the biosynthetic pathway of triterpenoid biosynthesis in Chenopodium quinoa. She is currently identifying and characterizing the upstream transcriptional regulators involved in triterpenoid biosynthesis, followed by the characterization of downstream enzymes involved in specialized metabolite (oleanolic acid) biosynthesis.

Abstract

Chenopodium quinoa is a nutritionally rich and climate-resilient pseudocereal gaining attention globally. Quinoa seeds are gluten-free and rich in protein and micronutrients. However, they taste bitter due to the presence of antinutritional oleanane-type triterpenoid saponins viz. oleanolic acid, hederagenin and ursolic acid. Oleanolic acid sapogenin is the major saponin found in C. quinoa seeds. Oleanolic acid-containing saponins are bitter and hemolytic. Oleanolic acid is synthesized by the cyclization of 2,3-oxidosqualene by beta-amyrin synthase followed by the oxidation of beta-amyrin. Oxidation of beta-amyrin is catalyzed by the action of cytochrome 450 enzymes. Plant genomes contain cytochrome P450 (CYP) supergene family involved in the biosynthesis of sapogenin aglycones. Here, by performing homology-based sequence analysis we identified a CYP716A in C. quinoa, which converts beta-amyrin into oleanolic acid. The functional validation was carried out by homologous transient overexpression and virus-induced gene silencing (VIGS) of CYP716A through agro-infiltration in the leaves of C. quinoa, followed by UPLC-MS quantification of the metabolites. Furthermore, heterologous expression in tobacco and Arabidopsis demonstrated the biological functionality of CYP716A in growth and stress responses. In summary, we discovered a novel beta-amyrin 28-oxidase enzyme (CYP716A) that catalyzes the biosynthesis of oleanolic acid in C. quinoa and explored its role in growth and defense. These results provide a strong foundation for understanding triterpenoid saponin biosynthesis in C. quinoa and designing saponin-free varieties.