S R Weerakoon
Open University of Sri Lanka, Sri Lanka
Title: Multiple origin of weedy rice (Oryza sativa f. spontanea) in Sri Lanka
Biography
Biography: S R Weerakoon
Abstract
The origin of weedy rice has long been a controversial issue and opinions on the origin of WR are greatly varied across
the scientific community. As far as Sri Lankan WR ecotypes are concerned, a geographical pattern of distribution which
associated with the wild rice and cultivated rice varieties in each climatic zone. Genetic diversity of 85 weedy rice eco-types,
60 cultivated rice varieties and 2 wild relatives distributed in wet, intermediate, dry zone were studied using 10 microsatellite
(SSR) markers distributed across the rice genome. Total genomic DNA was extracted from 7-day old seedlings of respective
WR eco-types, wild rice and cultivated types. A total of 10 SSR primer pairs were used for molecular study. Fragment analysis
using capillary electrophoresis was performed and identified different peaks among WR eco-types and wild rice varieties.
Obtained data were subjected to cluster (CA), principle component (PCA) and self-organizing map. Results of the PCA and
CA indicated that SSR distribution across the weedy rice eco-types, cultivated rice varieties and wild relatives provide strong
evidences supporting the hypothesis that the wild relative O. rufipogon and O. nivara ecologically diversified into wet and dry
habitats, respectively. Thus, origins of the weedy rice eco-types are results of the spontaneous hybridization and out-crossing
between wild relatives and cultivated rice varieties. Further, SOM imply that four out of 10 SSR primers (RM 211, RM 280,