DETECTION OF GENETIC VARIABILITY AMONG CHILLI GERMPLASM USING MOLECULAR MARKERS
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Date
2006
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD
Abstract
Assessment of genetic diversity is important for crop improvement
and also efficient management and protection of germplasm resources. Purposeful
plant breeding rests on the wise use of genetic resources. Chilli is an important spice
crop, which is consumed as spice and also as a vegetable. It contains oleoresins like
capsaicin and capsanthin, which impart pungency and colour to the fruits.
The present study was taken up with an objective to assess inter
accession diversity among 140 chilli germplasm accessions belonging to the species
C. annum L. collected from different origin/sources. 30 SSR marker primers were
selected for this study. All the marker primers were initially evaluated for annealing
temperature using a gradient PCR technique. Among the 30 marker primers
screened for polymorphism 6 marker primers were found to be polymorphic and
these 6 marker primers were used to analyze the 140 chilli germplasm accessions.
The maximum number of alleles detected was five with two primers and a least
number of two with one primer. Among the six primers one primer exhibited a large
number of null alleles, apart from this primer ten accessions showed null alleles
with different marker primers. So these were excluded from cluster analysis.
At these six loci a total of 21 alleles were detected with an average of
3.5 alleles per locus. The pair wise similarity based on Dice coefficient for all the
130 accessions ranged from 0.00 to 1.00. The cophenetic correlation coefficient (r)
computed between the observed distances and dendrogram was 0.66 which indicates
a good fit between observed distances and dendrogram. The clustering revealed that
the overall grouping of accessions is based on geographical association with few
exceptions. Further many accessions were found to be indistinguishable with a
similarity coefficient of one. In our analysis using 6 SSR marker primers about 32%
of genetic divergence was explained by the first 2 ordinates of the PCoA. The
cophenetic correlation coefficient (r) between observed distances and the PCoA was
0.81. The MDS plot showed the 130 accessions to be almost randomly spread over
two-dimensional Euclidian space with a cophenetic correlation coefficient of 0.6
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Keywords
DETECTION, GENETIC, VARIABILITY, AMONG, CHILLI, GERMPLASM, USING, MOLECULAR, MARKERS