RESPONSE OF DIVERSE RICE GERMPLASM TO BIOTIC AND ABIOTIC STRESSES
Location: Dale Bumpers National Rice Research Center
Title: A diverse collection of purified rice (O. sativa) accessions evaluated for genetic and agro-morphological diversity between sub-populations
Submitted to: International Rice Genetics Symposium
Publication Type: Proceedings
Publication Acceptance Date: September 30, 2009
Publication Date: November 15, 2009
Citation: Eizenga, G.C., Ali, M., Jia, M.H., Kimball, J.A., Bustamante, C.R., Mccouch, S.R., Mcclung, A.M. 2009. A diverse collection of purified rice (O. sativa) accessions evaluated for genetic and agro-morphological diversity between sub-populations. International Rice Genetics Symposium.
A diverse collection of 410 purified rice accessions originating from 77 countries was developed by identifying a representative plant from each accession. These accessions were fingerprinted with 36 SSR markers distributed throughout the genome and evaluated for 18 agro-morphological traits. A total of 330 alleles were detected with an average of 9.11 alleles per locus across all accessions, an average PIC value of 0.63 and gene diversity of 0.68. The accessions clustered into five ancestral subpopulations, indica (90 accessions), aus (60), aromatic (15), tropical japonica (105), and temperate japonica (107) by genetic distance-based clustering and model-based structure analyses. Thirty-three accessions with <60% ancestry from any single group were identified as ‘admixtures’. The genetic diversity was higher in the indica and aus subpopulations than in aromatic, temperate japonica or tropical japonica. Canonical discriminant analysis identified the traits, days to heading, plant height, panicle number per plant, flag leaf width, panicle length, and grain traits (length, width, weight and volume) as the main discriminatory characters. Both methods (SSR alleles, phenotypic traits) showed a close indica-aus and temperate-tropical japonica relationship and a distant relationship between the indica-aus and temperate-tropical japonica types, which agrees with the existence of two deeply divided major varietal groups, indica and japonica. Based on phenotypic traits the aromatic type was closer to indica-aus but based on SSR alleles closer to tropical japonica. This germplasm is being used in association mapping studies to better understand the process of domestication and breeding, especially as it relates to hybrids.