Exposing the genetic diversity of kalmegh [Andrographis paniculata (Burm. F.) Nees] germplasm through morpho-biochemical traits and SSR markers

The World Health Organization (WHO) underscores the significance of herbal medicines in attaining "Health for All." Among medicinal plants, kalmegh [ Andrographis paniculata (Burm. f.) Nees] is widely used in traditional medicine. It is valued for its potent bioactive compound, andrographolide, present mainly in its leaves, which possesses significant therapeutic and economic importance. Genetic diversity among Kalmegh genotypes offers potential to boost bioactive compound yield. Exploiting this diversity at morphological and DNA levels is crucial for crop improvement. In a recent investigation, the genetic diversity of 52 Kalmegh genotypes was comprehensively evaluated. This assessment considered six key morphological traits and two crucial biochemical attributes. Additionally, the genotypes were analyzed using 23 SSR markers, enabling a profound understanding of their genetic variability. Notably, discernible differences were identified between the morphological and biochemical traits. For instance, the plant height exhibited a range from 46.7 cm (DMAPR AP 126) to 75.2 cm (AKG 23), averaging 60.3 cm. Similarly, leaf length, breadth, and area displayed varying spans, from 4.2 cm (AKG 4.2) to 8.1 cm (Vallabh Kalmegh 1), 1.3 cm (AKG 64) to 2.4 cm (AKG 48), and 4.2 cm2 (AKG 56) to 10.6 cm2 (Vallabh Kalmegh 1), respectively. Moreover, the number of branches per plant and time to reach 50% flowering exhibited considerable diversity, ranging from 27.9 (AKG 65) to 44.0 (AKG 23) branches and 52.3 days (Anand Kalmegh 1) to 69.3 days (Vallabh Kalmegh 1). Significant variations in Andrographolide and neoandrographolide content were evident, notably in AKG 22 (0.62%) and AKG 25, AKG 54, DMAPR AP 76 (all at 0.16%). During principal components analysis, the first four components explained 74.33% of the total variation. Simple Sequence Repeat (SSR) markers revealed inter-genotypic dissimilarity ranging from 0 to 0.434, with a mean of 0.15, offering valuable insights into the genetic diversity among genotypes. The population structure analysis showed that the gene flow varied from 0.46 (subpopulations I) to 0.15 (subpopulations II). The study highlighted the potential of integrating morpho-biochemical traits and DNA markers to effectively differentiate Kalmegh genotypes, paving the way for breeding strategies aimed at enhancing bioactive compound production while leveraging genetic diversity. • Genetic diversity of 52 Kalmegh genotypes was performed. • Variations in Andrographolide and neoandrographolide content were recorded. • SSR marker revealed DMAPR AP 77 and DMAPR AP 121 as diverse genotypes.