Molecular Authentication and Phylogenetic Characterization of Curcuma aeruginosa Roxb. (Zingiberaceae) Using Chloroplast rbcL Gene Sequences

Abstract

Curcuma aeruginosa Roxb. (Zingiberaceae) is a medicinally significant species frequently confused with morphologically allied taxa such as C. caesia and C. zedoaria in the herbal trade. This study authenticates C. aeruginosa collected from Assam, India, using an integrative taxonomic framework through molecular, morphological and herbarium-based approaches. Ex-situ morphological validation revealed erect pseudostems with oblong-lanceolate leaves bearing reddish midribs, terminal inflorescences with pink bracts and bluish-violet rhizomes, which are diagnostic features consistent with C. aeruginosa. The specimen was taxonomically verified at the Botanical Survey of India, Coimbatore (Voucher No. BSI/SRC/5/23/2023/Tech–875). The rbcL gene was successfully amplified (564 bp) and sequenced (GenBank accession PQ287241). BLAST analysis showed 97% query cover and 96.15% identity with C. aeruginosa accessions (MK934697.1, KX758482.1), confirming its molecular identity. Phylogenetic analysis positioned the specimen within a distinct C. aeruginosa clade with strong bootstrap support (99%). This integrative study establishes a verified reference for C. aeruginosa within the Indian flora, reinforces its taxonomic distinctiveness, and highlights the importance of DNA barcoding for resolving identification ambiguities in Curcuma and related Zingiberaceae taxa. The study also highlights the practical importance of molecular authentication for ensuring correct identification of medicinal Curcuma species in herbal markets and pharmacognostic research.