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Microsatellite analysis of the correlation between molecular and morphological traits in assorted maize inbred lines
The success in identifying heterosis in hybrid maize ( Zea mays L.) breeding depends on the availability of reliable genetic diversity among maize inbred lines. Conventional methods of breeding have been boosted by the availability and efficiency of molecular markers. Coupling simple sequence repeat...
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Published in: | African crop science journal 2009-11, Vol.17 (3) |
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Main Authors: | , , , , |
Format: | Article |
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Summary: | The success in identifying heterosis in hybrid maize ( Zea mays L.)
breeding depends on the availability of reliable genetic diversity
among maize inbred lines. Conventional methods of breeding have been
boosted by the availability and efficiency of molecular markers.
Coupling simple sequence repeat (SSR) markers with morphological
markers provides thorough starting information for new inbred lines,
especially from different genetic backgrounds. Furthermore, recent
evidences that the environment can influence the epigenetic structure
of the genome have necessitated morphological screening of crops during
breeding programmes. This study used 28 agronomic traits and 14 SSR
markers which are distributed uniformly in ten (1-10) inbred lines,
namely EM11-133, EM12-210, OSU23i, CML395, CML202, CML442, CML444,
CML208, CML312 and CML204 from Kenya, International Centre for the
Improvement of Maize and Wheat (CIMMYT), and another (OSU 23i) from
USA. The aim was to investigate their morphological and genetic
diversity, categorise the inbred lines into useful groups based on the
molecular profiles and morphological traits, and lastly determine the
level of phenotype-genotype correlation. The dissimilarity calculated
using SSR markers had a mean morphological dissimilarity of 0.895403,
an r value of -0.1421 and a p -0.9840. The dissimilarity between the
molecular and morphological traits was 0.860465. Comparison between the
molecular and morphological data had a dissimilarity matrix with an r
-0.2323 and a p value of 0.0120. This was probably due to intrinsic
synteny in maize genome. The dendrograms generated with hierarchical
Unweighted Pair Group Method with Arithmetic mean (UPGMA) cluster
analysis of the Jaccard's similarity coefficient matrices revealed four
major clusters. The Co-ancestry distance showed six tied groups with
the Kenya cluster showing some differentiation with Exact Tests for
population differentiation with a p = 0.0513. The American inbred line
(OSU 23i) segregated alone, while the Kenya lines (EM11-133 and
EM12-210) had close homology with the CIMMYT inbred lines (CMLs). A
total of 2.0 alleles were detected among the inbred lines using bulk
DNA samples and 14 SSR loci. Clustering analysis based on the genetic
similarity coefficients separated the inbred lines into 4 groups with
the American inbred line seeming to be genotypically more diverse from
the others. |
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ISSN: | 1021-9730 2072-6589 |