Inter Simple Sequence Repeats (ISSRs) Fingerprinting, Phenotypic Variability and Trait Associations in Released and Elite Rice (Oryza sativa L.) Genotypes of Ethiopia
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Date
2011-04
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Addis Ababa University
Abstract
A study on the morphological and molecular characterization of rice (Oryza sativa L.) varieties
and lines of Ethiopia was carried out in 2009/10 cropping season. A total of 18 released and elite
rice varieties of Ethiopia were used. Inter simple sequence repeats (ISSR) was used as a
molecular marker to assess genetic diversity within and among varieties using five ISSR primers
(810, 824, 834, 873 and 878). A total of 75 clear and reproducible bands were amplified, out of
which 62(82.67%) were observed to be polymorphic. The number of polymorphic loci ranged
from 8 for primer-873 to 16 for primer-810. The lowland rice genotypes showed the highest
polymorphism (74.67%), followed by upland (61.33%) and NERICA varieties (57.33%). In the
same fashion, genetic diversity analysis indicated that lowland rice genotypes showed higher
diversity (0.27) than both upland (0.25) and NERICA varieties (0.23). The over all genetic
diversity of Ethiopian rice was found to be 0.29. The un-weighted pair group method using
arithmetic mean (UPGMA) and neighbor joining trees clustered the genotypes in to their
respective ecosystem Lack of purity in IREM-194, HO-04 and AD-12 was prevalent from the
constructed trees and field observation. The principal coordinate analysis (PCO) also recovered
the UPGMA and neighbor joining tree groups. Analysis of molecular variance (AMOVA)
revealed that higher percentage of variation was attributed to variation within individuals
(88.67) and the variation among groups was lower (11.33).In the morphological study, which
was carried out in a randomized complete block design (RCBD) with three replications, 23
qualitative and 13 quantitative traits were evaluated based on the standard procedures given by
International Rice Research Institute and Bioversity International. The result of all diversity
parameters indicated that there exists a clear difference among the genotypes for all the traits
considered. Analysis of variance (ANOVA) and Duncan’s multiple range test (DMRT) revealed
the variability of the genotypes for each of the 13 quantitative traits. Phenotypic coefficient of
variation (PCV) varied from 5.38% for number of days to heading to 20.49% for leaf length.
Similarly, genotypic coefficient of variation (GCV) ranged from 5.36% for number of days to
heading to 19.47% for leaf length. Higher heritability values were observed for all the 13
quantitative traits, out of which nine traits showed heritability percentage more than 90 %. It
ranged from 98.98% for number of days to heading to 55.13% for grain yield. Correlation of
traits showed that most of the traits were associated. Cluster analysis using morphological data
grouped all the test materials in to two main clusters but failed to strictly cluster the genotypes in
to their respective ecosystems. Principal component analysis (PCO) showed that the first three
principal components explained about 86.81 % of the total variation. Generally, the study
indicated the existence of narrower genetic diversity among the genotypes which calls for timely
action to widen the genetic diversity of Ethiopian rice so as to combat the devastating outcome of
having narrower genetic diversity in cultivated crops.
Key words: Rice (Oryza Sativa L.), ISSR, genetic diversity, trait association
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Keywords
Rice (Oryza Sativa L.), ISSR, genetic diversity, trait association