IDENTIFICATION OF PARENTAL POLYMORPHISM USING SSR MARKERS AND EVALUATION OF SEGREGATING POPULATION FOR RUST RESISTANCE IN COWPEA (Vigna unguiculata L. Walp).
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Date
2009-09-15
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University of Agricultural Sciences, Bangalore
Abstract
A study was conducted to identify polymorphic SSR markers among nine
parental lines of cowpea and to estimate inheritance pattern of rust resistance in F2
population of C-152 X IC 68786 during kharif 2008 at Main Research Station, Hebbal,
University of Agricultural Sciences, Bangalore.
Microsatellite aided diversity analysis revealed low percentage of
polymorphism. Out of 36 SSR primers, four were polymorphic with two to four alleles
per locus. Primers VM 1, VM 28, VM 36 and VM 68 produced polymorphic bands and
polymorphism percentage was 11.11.
Dendrogram constructed with polymorphic markers grouped nine genotypes
into seven clusters. Clustering was in accordance with geographical origin and
distinguished the cultivated varieties from the landraces.
Susceptibility was dominant over resistance in the following F1s viz., C-152 X IC
68786, C-152 X IC 243353 and C-152 X IC 219607. The inheritance studies of rust in F2
population produced majority of moderately susceptible and susceptible plants and a
few resistant, moderately resistant and highly susceptible plants. Polygenic control of
rust resistance was supported by rare occurrence of extreme phenotypes, transgressive
segregants and continuous segregation for per cent leaf area under rust infection in F2
population. Further, the frequency distribution of per cent leaf area under rust
incidence was normal and platykurtic.
Estimates of PCV and GCV indicated high variability for seed yield per plant,
number of pods per plant and number of clusters per plant. Heritability estimates were
high for yield and yield contributing characters with moderate to high genetic advance
indicating action of mainly additive genes in controlling the above.
Significant positive association of all the component characters with seed yield
per plant was observed. Segregating population of C-152 X IC 68786 produced 2.53 per
cent of superior segregants in respect of seed yield and its contributing traits combined.
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