Cytogenetic diversity and phylogeny of Pancratium (Amaryllidaceae): Taxonomic insights into a medicinal bulbous geophyte

The genus Pancratium, belonging to Amaryllidaceae, has widespread therapeutic utility mainly owing to presence of bioactive alkaloids. However, its taxonomical relationships remain inadequately explored, resulting in an ill-defined infra-generic classification. This necessitates further investigation using cytogenetic and molecular phylogenetic approaches, which can further clarify taxonomic relationships. Existing reports on such attributes are scattered across the literature, making the collation and consolidation of data a prerequisite for further analysis. The present review ascertained that cytogenetic characterization has been initiated in less than 50% of accepted Pancratium species, with no data for unplaced species. Most species exhibit a chromosome count of 2n=22 and n=11, suggesting widespread homoploidy, with dominance of asymmetric karyotype with x=11 as the most probable basic chromosome number. Nuclear genome size estimations are reported only in two species, with 2C values of 36.30 pg and 60.10 pg in P. illyricum and P. maritimum, respectively. Karyological studies have been done only in six species with mostly bimodal or graded asymmetric karyotypes and predominance of chromosomes with submedian to subterminal primary constrictions. Fluorochrome chromosome banding is reported only in P. illyricum and P. maritimum, both exhibiting CMA positive bands associated with nucleolar organizer regions identified by FISH. Thus, from the present review it is evident that the genus Pancratium exhibits widespread cytogenetic diversity with probable taxonomic utility but awaits the exploration of these traits in most species for further implications. Research on Mediterranean species using chloroplast non-coding DNA (cpDNA) sequences suggests the possible existence of a P. maritimum species complex. However, similar studies are limited in Asian species and entirely absent in Indian taxa, underscoring the need for further investigation. Correlation of such molecular phylogenetic analysis with karyological data and genome size can help in further elucidation of taxonomic relationships by establishing either distinctiveness or diversity of the established groups. However, such analysis is limited in literature and awaits further exploration.