Molecular Plant Breeding 2016, Vol.7, No.11, 1
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self-pollinate. However, since out-cross in
Capsicum
is very high and pepper in Eritrea is mainly produced
by small holding farmers who grow different varieties
in close proximity to each other which favours
cross-pollination; the high Ho obtained in the current
study is justified.
Variation among populations was relatively low (10%)
and most variation in the total population was within
individuals (60%) and among individuals within
populations (30%). This was similar to the 12%
among populations reported by Tesfamichael et al.,
(2014) studying Eritrean sorghum landraces but in
contrast to the 31% and 57% within individuals and
among individuals respectively reported in the same
study. The results also are in contrast with the findings
of Backes et al., (2009) who reported within field
variation in Eritrean barley to be 97.3 %. There is no
documentation on when pepper was introduced it
Eritrea, but oral reports indicate that it has been grown
in for very long time (Saleh et al., 2013). Selection of
superior genotypes, carrying it over generations and
acquiring seeds from trusted farmers within the village
or distant places are common practices of pepper
growers in Eritrea. This gives a chance for variants to
be selected and fixed which may explain the relative
high heterozygosity (Table 1) and availability of rare
alleles(Table 2) leading to existence of significant
amount of diversity within Eritrean pepper
germplasm.
2.2 Pair wise genetic dissimilarity among
population
Generally, the results indicated low dissimilarity
among populations compared to the results of Geleta
et al., (2005) who compared Ethiopian pepper
genotypes each other and with genotypes from
AVRDC and other countries using AFLP markers. In
the current study, two groups appeared to have low
genetic distance (Table 4) and high average number of
effective individual migrants (Table 6).The first group
is composed of the populations Afabet, HAC and
NARI. The genetic distance between Afabet and HAC
was 0.056, Afabet and NARI was 0.079 and HAC and
NARI was 0.071. This group was closer to the
AVRDC population than to the rest of the Eritrean
populations. Compared to the other populations, this
group also showed closest distance with the KALRO1
and the outgroup KALRO2 (tomato) populations. The
most probable reason for the close genetic distance
among the three populations (Afabet, HAC and NARI)
is that breeding lines from NARI are from local
sources and served as source of seed for Afabet. Later
on, breeding program started at HAC and benefited
from the available local sources. This is evident from
the high Nm levels among the three populations that
ranged from 7.976 between Afabet and HAC to 8.144
between NARI and HAC (Table 6). The second group
is composed of Gindae, Dbarwa, Medefera,
Dekemhare and Elabered, with genetic distance
ranging from 0.086 between Gindae and Dekemhare
to 0.117 between Gindae and Mendefera. This group
had higher distance with AVRDC ranging 0.20-0.302
with Gindae and Mendefera respectively. Compared to
the previous group, this group was also highly
dissimilar with both KALRO1 and KALRO2. The
close distance in this group could be due to intensive
seed exchange among farmers in these areas. The high
level of immigration observed among these
populations expressed by the Nm is evidence for that.
The highest Nm was 10.499 between Dekemhare and
Gindae followed by Nm= 9.777 between Elabered and
Dubarwa (Table 6).
2.3 Population structure
Based on the Neighbor-joining clustering and
STRUCTURE, the populations under study were
grouped into three clusters, and increasing the number
of populations in STRUCTURE resulted in forming a
separate cluster for the non-Eritrean accessions. This
is in contrast to similar study conducted in Nepal
where all the local accessions clustered in a single
cluster (Baral and Bosland, 2002). Most of the
breeding lines and large number of farmer varieties
from the sub-region Afabet grouped together in cluster
3. The reason could be that breeding lines in both
NARI and HAC are as a result of mass selection from
an original local seed source in two separate breeding
programs. Afabet is a new pepper production area,
farmers in this area acquired seeds from different
sources, therefore lines from NARI that have been
released to farmers may be found in this area and
crossed with genotypes from other sources. A
breeding program started at HAC using local seed
sources and continued to select superior genotypes to
meet market requirements. Later on, selection by
farmers led to genotypes with common ancestry to be
