Abstract:
A large number of traditional rice accessions belong to Sri Lanka, which may serve as a valuable
genetic resource for the improvement of rice mainly in terms of biotic and abiotic stress
resistance and nutritional upgrades. However, these varieties are rapidly being disappeared due
to replacement of agronomically improved inbred varieties. The utilization of traditional rice
germplasm in rice quality improvement is currently being practiced upon morphological
features. A detailed understanding of the genetic structure and diversity of traditional rice
accessions is vital for efficient utilization of rice genetic resources and identify potential parents.
In the present study, 33 SSR markers were used to assess genetic diversity and relatedness
among 31 rice accessions including 151 individuals from plant genetic resource centre, Sri
Lanka. All 33 loci displayed polymorphism (66.7-96.9 %) among the 31 accessions, 387 alleles
identified with an average of 11.72 alleles per accession. Moderately high genetic diversity was
found for accession 4770 (HE= 0.561), while the accession 3947 recorded the lowest (HE= 0.344)
diversity. The AMOVA results indicated that 34% of the variation distributed among accessions,
59% among individuals and 7% within individuals, indicating a comparatively high level of
genetic differentiation among individuals of selected rice accessions. Structure analysis results
illustrated that all 31 accessions were genetically structured into fifteen well-separated groups,
high ΔK peaks were recorded at K=15, K=5, K=19 and K= 2, respectively. Accessions viz. 12818,
2504, 2340 and 3470 showed low admixture while 2087, 4236, 3440 showed a moderately high
rate of admixture. UPGMA results indicated accessions: 4236, 4595, 2119 were differentiated
from all other accessions. This genetic diversity assessment at the molecular level provides
reliable information to avoid duplication of traditional rice accessions/varieties in the gene bank
at plant genetic resource centre and selection of germplasms to develop new rice varieties.
Therefore conservation of traditional rice genetic resources for future breeding programs is vital
important.
