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Legume Genomics and Genetics (online), 2010, Vol. 1, No.4, 18-23
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21
2 Discussion
Conventional plant breeding methods have been effe-
ctive in bringing about improvement but efforts are
still being made to develop more efficient breeding
methods to overcome specific problem (Arshad, 2004,
http://eprints.hec.gov.pk/2072/1/ 1991.htm; Fondevilla,
2005). Contradictory reports regarding the inheritance
of powdery mildew in pea have been reported by
different authors. Resistance to powdery mildew in
pea was first reported as monogenic recessive with the
gene symbol
er
by Harland (1948) as digenic i.e.,
er1
and
er
2 (Heringa et al., 1969; Kumar and Singh,
1981). Fondevilla (2007) identified a new gene
er
3 for
resistance to powdery mildew in
Pisum fulvum
and
wild relative of pea based on morphological traits. While
in the present study an ideal condition was provided to
investigate the exact nature of powdery mildew sen-
sitivity. It was concluded that all F
1
generation showed
the susceptible phenotype indicating the dominance of
susceptible allele over the resistant allele. The F
2
generation for powdery mildew disease segregated
with 3:1 ratio, which was fit for goodness by χ
2
test. It
was concluded that
er-1
gene is controlled by two homo-
zygous recessive alleles. All the reaming quailtative
traits also showed monogenic nature of inheritance.
In the present study it was find that anthocyanin pig-
mentation linked with flower colour and seed colour,
while tendril type linked with number of leaflet per
leaf. None of the qualitative trait was linked to pow-
dery mildew disease. The finding is needed to be ex-
plored through biochemical and molecular markers
(Zhang, 2004,
etd-08222004-120704/unrestricted/thesis.pdf). The gene
expression and traits interaction can also be explored
using serial analysis of gene expression (SAGE) as
developed by Velculescu et al., (1995) is a high-
throughput method to determine the absolute abun-
dance of every transcript in a population of cells (Mat-
sumura et al. 2005; 2006).
Breeding is the option to bring heterogeneity and
vigor in the germplasm reported by Ghafoor et al.
(2003). In the present study F
3
generation calculates
maximum level of coefficient of variation for total pod
weight and number of seeds/pod. It is widely recog-
nized that variation is the basis of improvement. Corre-
lation is the measure of the degree to which variables
vary together or a measure of intensity of association.
Guler et al. (2001) studied linear relationship among
yield and yield component. Similarly high signi-
ficantly positive correlation was observed in all stu-
died yield contributing traits except between number
of seeds/pod and seed weight. Based on yield contri-
buting quantitative traits evaluation in comparison
with checks variety (DASAN), three lines GN07
0140
-
2, GN070143
-
1 and GN070140 were selected
as high yielding powdery mildew resistant lines. The
novel high yield powdery mildew resistant lines is
super lines which can replace DASAN due to high
yield and negative response to powdery mildew
disease caused by
Erysiphi pisi
. The lines are most
suitable for cultivation in Pakistan. These lines were
systematically conserved in Bannu GeneBank, Depart-
ment of Biotechnology, University of Science and
Technology
Bannu
, NWFP, Pakistan.
From the present study it is concluded that powdery
mildew resistance gene (
er-1
gene) is under the con-
trol of homozygous recessive allele. It also indicated
that anthocyanin pigmentation linked with flower, pod
and seed colour. While tendril type and flower colour
linked with number of leaflet per leaf and pod colour
respectively. Similarly it was investigated that none of
the qualitative trait linked with powdery mildew disease.
All these linked traits should be used in MAS bree-
ding and gene mapping. Three novel high yielding
lines were selected and should be used as cultivars,
needed further improvement. To enhance the food
value and for economic benefits the breeder selects
high yielding and resistant cultivars and discord the
high yielding susceptible or low yielding resistant
lines. It is suggested that, conserve all the population,
especially high yielding susceptible or low yielding
resistant lines in the GeneBank for molecular chara-
cterizations and other biotechnological uses.
3 Materials and Methods
3.1 Screening of germplasm
A total of 177 genotypes obtained from different part
of the globe were planted in the screen house at the
Institute of Agri-Biotechnology and Genetic Resources,
National Agricultural Research Centre, Islamabad,
Pakistan during winter 2004~2005. Optimum condi-
tions for fungus growth were provided during the
experiment, the genotypes showed resistances under
natural infection were artificially inoculated with
Erysiphe pisi
conidia by tapping heavily infected plant