Chromosomal variations in twelve ecotypes of a medicinal plant Drimia indica (Roxb.) Jessop: karyotypes and 2C DNA content analysis

Indian Squill (Drimia indica) belonging to the family Asparagaceae is a highly medicinal herb with several therapeutic properties. The cytotaxonomic complexity of the species Drimia makes it intriguing to investigate ploidy variation in ecotype level and its significance in relation to genome size variation. Detailed karyotype analysis and 2C DNA contents were reported in twelve ecotypes of D. indica from different geographical locations of the state Odisha, India. The diploid somatic chromosome 2n = 2x = 20 was recorded in four ecotypes such as 'Kendrapada', 'Tikarpada', 'Daspalla', and 'Odagaon, while tetraploid having 2n = 4x = 40 was newly reported in ecotype from 'Nuagaon'. Aneuploid chromosome number 2n = 26 was obtained in ecotypes 'Similipal' and 'Satkosia' and 2n = 32 was newly reported in ecotypes 'Bitarkanika' and 'Narasinghpur'. The ecotypes 'Nayagarh' and 'Nilagiri' were recorded with 2n = 16 and 2n = 22 respectively. The 2C DNA content analysis showed 2.19-fold increase which correlates with ploidy variation in ecotype level. The 2C DNA values were found highest of 36.26 pg (2n = 40) in ecotype 'Nuagaon' and lowest at 16.54 pg (2n = 16) in ecotype 'Nayagarh' that corresponds with ploidy and genome size. The asymmetry in the karyotypes showed non-significant clusters among the ecotypes except ecotypes 'Odagaon' and 'Bhitarkanika' which are most asymmetric having advanced karyotypic features as compared to the ecotypes 'Simlipal', 'Karanjia' and 'Nayagarh' having symmetric karyotypes. The chromosome characteristics along with genome size analysis of D. indica can be very useful in establishing genome-specific cytotypes which can be used for breeding programme for crop improvement. Furthermore, enhancement of therapeutic phyto-constituents, and cyto-taxonomic identification from adulterant and confirmation of alloploidy or autoploidy through genomic in situ hybridization could unravel the potential of this plants in relation to secondary metabolite production.