Ecotype variations in karyotypes and 2C DNA content in Drimia indica (Roxb.) Jossop: An important medicinal plant

Abstract

Indian squill (Drimia indica) belonging to the family Asparagaceae is a highly medicinal herb with several therapeutic properties. Detailed karyotype analysis and 2C DNA contents were reported in twelve ecotypes of D. indica from different geographical locations in the state of Odisha, India. The diploid somatic chromosome 2n = 20 was recorded in four ecotypes ODi-16 (Kendrapada), ODi-23 (Tikarpada), ODi-24 (Daspalla), and ODi-26 (Odagaon) while tetraploid having 2n = 40 was newly reported in one ecotype from Nuagaon (Eco-ODi-06). Aneuploid chromosome number 2n = 26 was obtained in ecotypes from Similipal and Satkosia besides 2n = 32 was newly reported in ecotypes from Bitarkanika and Narasinghpur. The ecotypes ODi-22 (Nayagarh) and ODi-11 (Nilagiri) were found to be with 2n = 16 and 2n = 22 respectively. The 2C DNA content analysis showed a 2.19-fold increase which is confirmed by an increase in the number and chromosome length of ecotypes. The 2C DNA values were found highest at 36.26 p.g. (2n = 40) in Eco-ODi-06 (Nuagaon) and lowest 16.54 p.g. (2n = 16) in Eco-ODi-22 of Nayagarh that corresponds with ploidy and genome size. The asymmetry in the karyotypes showed non-significant clusters among the ecotypes except ecotypes ODi-26 (Odagaon) and ODi-2a (Bhitarkanika) which are most asymmetric having advanced karyotypic features as compared to the ecotypes ODi-01, ODi-08 and ODi-22 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 programs for crop improvement. Furthermore, enhancement of therapeutic phytoconstituents and cyto-taxonomic identification from adulterants and confirmation of allopolyploidy or autopolyploidy through genomic in situ hybridization could unravel the potential of this plant in relation to secondary metabolite production.