Morphological and molecular characterization of novel salt- tolerant germplasms of rice (Oryza sativa L.) from the Philippines and Bangladesh

Date

4-2012

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Ivan Marcelo A. Duka

Abstract

For the purpose of mining new sources of salinity tolerance, 688 traditional rice ' varieties from the Philippines and Bangladesh were screened to assess their tolerance to hypersaline conditions at the seedling stage. A total of 29 Philippine lines and 15 Bangladesh lines were scored as salt-tolerant. Morphological assessment of various physio-morphometric characters was done for each variety, namely: plant height, biomass, and sodium-potassium (Na-K) ratio. When percent shoot length reduction was computed for each accession, two genotypes, Betalga and Maranao, were found to have a percent reduction that is lower than that of FL478 (tolerant check) indicating a good tolerance mechanism. Seventy-five percent of the population was found to have a mean shoot Ibiomass percent loss that is statistically similar with that of FL478. For both the shoot fresh and dry weight percent growth reduction, 48% and 70% of the population, respectively, had values that were lower than FL478. A similar trend was observed for the root percent growth reduction. The Na-K ratio proved to be a good measure of salinity tolerance with a Pearson's correlation coefficient of 0.78 when paired along with the Standardized Evaluation Score (SES). The accession AC obtained a Na-K ratio that is statistically lower than that of FL478 indicating a good tolerance mechanism. For the purpose of determining the genetic diversity of the 46 genotypes, 33 SSR markers were used. A total of 129 alleles were detected across all loci and nine markers were found to detect heterozygotes. The P1C values of 18 markers were found to be highly informative (PIC > 0.5). Cluster analysis at a similarity index of 2.5% showed that the Bangladesh accessions: Roa, Napatasa, Chondoni, Moisdol, Asha, and Jakor, were genotypically different from the other accessions. Furthermore, at a similarity index of 6.5%, AC, Akundo, and Kuplod were clustered along with FL478 indicating a strong genetic relatedness between these genotypes across all loci. Casibon was also found to be singly separated. The said accessions are of interest since the genotype each represent might be different from the classical salinity-tolerant Pokkali-type. Finally, the haplotype analysis revealed that none of the 44 genotypes have a similar allele combination as FL478.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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