Rice Breeding Program (RBP) of the Instituto de Investigaciones
Agropecuarias (INIA) at Chillán, Chile, has a rice (
Oryza sativa
L.) germplasm collection that consists of 1200 accessions,
mainly temperate
japonica rice accessions, well adapted to the
local conditions. Most of the new introduced accessions adapt
very poorly to Chilean agroecological conditions because of
requirements of long days and cold tolerance. The objectives
of this study were to use microsatellites to evaluate level of
polymorphism of a representative sample of this collection and
determine its genetic diversity and relationships with cultivated
germplasm from different geographical origin. A total of
249 genotypes were analyzed with 30 selected polymorphic
microsatellites. Total number of alleles scored across 249
genotypes was 183 with an overall mean of 6.1 alleles per
locus,
ranging 2-14. The mean major allele (most common) frequency
was 0.61 and mean minor allele frequency was 0.028. The
overall mean gene diversity across 30 SSR
loci was 0.52. Mean
heterozygosity was 0.01, and mean polymorphism information
content (PIC) value was 0.47. The accessions were organized by
structure analysis into three main groups and revealed a fairly
consistent genetic relationship with dendrogram and Principal
Coordinates Analysis (PCoA). The temperate
japonica
accessions can be further subdivided into three subpopulations
where long and short grain Chilean varieties were grouped into
different clusters. The three populations showed different level
of admixture, admixture probably due to previous breeding
work through years. Results indicate that polymorphism levels
of Chilean rice temperate
japonica collection has similar
magnitude as temperate
japonica germplasm reported in the
literature.
