De novo plastome assembly of Cymbopogon bhutanicus Noltie, an endemic lemon grass from Bhutan, with geospatial, comparative genomic, and phylogenetic insights

Abstract

Cymbopogon bhutanicus Noltie, an endemic Bhutanese Poaceae, is valued for its essential oils. While morphological taxonomy offers preliminary insights, molecular data enhances species delimitation. We performed de novo chloroplast genome assembly and used remote sensing to assess environmental influences on its distribution. Geospatial analysis of C. bhutanicus habitat (27.25952°N, 91.40823°E) within a 2km buffer zone utilized Sentinel-2 imagery (2018-2023). Mean Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Soil-Adjusted Vegetation Index (SAVI) values were 0.5974, 0.3356, and 0.3300, respectively. These values indicate robust vegetation health, while observed variations (e.g., NDVI standard deviation of 0.1780) highlight localized microhabitat heterogeneity influenced by topography and moisture gradients. Field observations aligned, confirming its preference for open, well-drained, sun-exposed slopes with minimal canopy. The assembled chloroplast genome (139,701 bp; 38.46 % GC) comprises an 81,663 bp LSC, 12,510 bp SSC, and two 22,764 bp IR regions. Annotation identified 129 genes (87 protein-coding, 34 tRNA, eight rRNA). Phylogenetic analysis confirmed a strong relationship with C. citratus and C. flexuosus (100 % bootstrap). This study enhances C. bhutanicus molecular identification, phylogeny, and ecological understanding, aiding conservation and sustainable use. This study enhances molecular identification, phylogenetic placement, and ecological understanding of C. bhutanicus, contributing to conservation efforts and sustainable utilization.