Unraveling the genetic diversity of local Thai Cannabis strains using Inter-Simple Sequence Repeat (ISSR) molecular markers

Abstract

Cannabis sativa, an emerging economic crop in Thailand, has been cultivated in various regions of the country. The objective of this research was to examine the genetic relationships of local Thai Cannabis strains using five inter-simple sequence repeat (ISSR) molecular markers. A total of 50 Cannabis samples were evaluated, encompassing named local strains, unidentified landraces, and a hemp variety. The analysis yielded a total of 52 DNA bands, of which 51 were polymorphic, ranging in size from 300 to 1,500 bp. Based on UPGMA cluster analysis at a genetic distance cutoff of 0.25, the accessions were clearly separated into four distinct groups. Group 1 (bootstrap score: 96.6%) comprised local landraces such as Chiang Rai Dang Kan Kew and Green Thai Stick. Group 2 (bootstrap score: 92.6%) included high-cannabinoid and regional varieties, notably the CBD strain, Kanchanaburi, and Thai Stick. Group 3 (bootstrap score: 95.8%) predominantly clustered the MJUS breeding lines alongside accessions from Sakon Nakhon and Nakhon Phanom. Group 4 (bootstrap score: 77.2%) consisted of the Isara series and Kra Le. This study demonstrated that ISSR markers are highly effective in distinguishing the genetic structure of local Thai Cannabis strains, providing valuable baseline data for germplasm conservation, phytochemical standardization, and future medical breeding programs.