Legume Genomics and Genetics 2015, Vol.6, No.2, 1-7
2
birth while zinc deficiency causes stunting and
reduces immunity against disease causing organisms
(Welch and Graham 1999, 2004). Keeping these
facts in view, in this study we evaluated the
common bean genotypes for seed Fe, Zn & protein
contents in order to identify superior genotypes that
can act as a genetic resource for mining
alleles/QTLs contributing for higher amounts of Fe
and Zn. These genes/QTLs can further be
introgressed in desired background through
molecular breeding for enhancing nutritional value
of common bean varieties.
1 Results and Discussion
1.1 Evaluation of common bean genotypes for Fe,
Zn, & protein contents in seed material
Fe, Zn, and protein contents in the seeds of 51 diverse
genotypes of common bean were estimated to
determine the variation among them. Wide variation
was found in Fe concentration ranging from 0.71 to
7.22 mg 100g
-1
with an average of 1.81 mg 100g
-1
.
Genotype R2 possesses highest seed Fe content (7.22
mg 100g
-1
) whereas genotype K12 has lowest Fe
content (0.71 mg 100g
-1
). The Zn concentration in
seed varied from 0.43 to 1.93 mg 100g
-1
with an
average of 0.78 mg 100g
-1
. Genotype K15 possesses
high Zn content in seed (1.93 mg 100g
-1
) whereas
genotype KS6 has lowest Zn content (0.43 mg 100g
-1
).
Table 1 and Figure 1 represent the mean values of Fe
and Zn content observed in seeds of 51 diverse
common bean genotypes. In earlier reports, we
observed a similar pattern of variation in Fe & Zn
content in common bean seeds. Silva et al. (2010)
observed a wide variation in Fe & Zn contents among
100 diverse common bean lines ranging from 54.20 to
161.50 mg kg
-1
and 29.33 to 65.50 mg kg
-1
, Fe and Zn
respectively. Similarly, another study also revealed a
variation in Fe and Zn content from 34 to >100 mg
kg
-1
and 21 to 54 mg kg
-1
, respectively among 2000
common bean accessions of CIAT (Beebe et al.,
2000). In a recent report, 117 genotypes of common
bean collected from Uganda showed variation in Fe
and Zn contents ranging from 45 to 87mg kg
-1
and
22 to 40mg kg
-1
, respectively (Mukamuhirwa et al.,
2012). Since, there is a huge variation in Fe and Zn
contents in our material, we, suggest that, genotypes
with highest Fe and Zn can be used as genetic
resource for improving nutritional quality of
adopted common bean cultivars.
We further analyzed seeds for their protein content,
which ranged from 7.2% to 31.6% with an average
content of 20.30%. Highest protein content was
observed in KS6 (31.6%) whereas genotype K12 had
the least protein content of 7.2%. Table 1 and Figure 1
represent the mean values of protein content observed
in seeds of 51 diverse common bean genotypes.
Similar results have been reported in previous studies,
although variation between the content may be due to
the environmental factors, geographical location, and
growing season. In earlier reports, the variation in the
seed protein content was observed ranging from 17.4%
to 29% (Sood et al., 2003; Silva and Iachan, 1975;
Sgarbieri et al., 1979; Márquez and Lajolo, 1981,
Durigan & Sgarbieri, 1985; Durigan et al., 1987 &
Tezoto & Sgarbieri, 1990). Protein content of 36
North American bean cultivars evaluated by Koehler
et al., (1987) also ranged from 19.6 to 32.2%. A wide
range in micronutrient and protein contents among 51
genotypes in this study indicates the existence of
extensive genetic variation which can be explored for
enhancing nutritional value of common bean varieties.
Further, we grouped these 51 genotypes on the basis
of their mean values (Table 2) to cluster them based
on particular range of micronutrient (Fe and Zn) and
protein content.
1.2 Variation in Fe, Zn, and protein among the
genotypes and within the genotype
The comparison of Fe, Zn, and protein contents
revealed non-significant differences among most of
the genotypes, whereas the comparison of the Fe & Zn,
Zn & Protein, and Fe & protein contents within the
genotype indicated that, these traits are significantly
different except three genotypes detailed in (Table 1).
1.3 Correlation among micronutrient (Fe & Zn)
and protein contents
Negative but non-significant correlation was found
between Fe and Zn (r=-0.022; p>0.05), Fe and protein
(r=-0.037; p>0.05), and Zn and protein (r=-0.037;
p>0.05) (Figure 1, Table 3). In an earlier study, Zn &
Fe content in common bean seeds were found
inversely correlated (r=-0.11; p<0.05) (Akond et al.,
2011). Thus, it can be interpreted that accumulation of
one micronutrient (in this case Fe or Zn) has negative
impact on concentration of the other, as such there is a
genetic regulation governing the transport and
accumulation of these micronutrients.
