MAPPING OF THE REGIONS ASSOCIATED WITH IRON CONTENT IN RICE GRAINS
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Date
2008
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD.
Abstract
The present study was conceptualized and executed involving the rice
germplasm(87 genotypes) using SSR markers derived from the genomic regions
associated with iron metabolism, and progeny tested F2 mapping population (92
individual plants) derived from the cross BPT 5204 and Chittimuthyalu. Genetic diversity
of 87 rice varieties using microsatellite primers was studied using two markers viz., SC
120 and SC 123 (based on the yellow stripe like genes) for cluster analysis. No
significant grouping based on the iron content in the grains could be obtained. Since the
trait of iron accumulation in grains controlled by the many genes and the markers used in
this study were of limited number, more markers preferably functional markers would
elicit the genetic diversity of characterized germplasm.
Out of the 45 microsatellite markers used for the parental polymorphism studies
between BPT 5204 and Chittimuthyalu, 13 markers showed polymorphism and 14
markers showed monomorphism suggesting the diversity of the selected parents in
addition to their high iron content in the grains.
Out of the three markers analyzed in the present study, all the three markers found
to be associated with iron content in the grains. The SC 103 marker is located on the
chromosome 3 and the putative candidate gene sequence was found between 26114338 –
26248438 bp. The linkage distance between this marker and the gene Os Zinc transporter
was calculated to be 45.6 cM.
The SC 129 marker is located on the chromosome 3 based on microsatellite
marker identified in the region of Os ZIP1 gene and putative candidate gene sequence
was found between 16921118 – 17018159 bp. Linkage distance between this marker and
the gene was calculated to be 56.7 cM. The reported chromosomal position of this gene
in Nipponbare genome estimated in accordance to genetic markers assigned to the
BAC/PAC clones (as shown by TIGR genetic map) was 83.3 cM.
The SC 131 marker is located on the chromosome 6 based on microsatellite
marker identified in the region of Os ZIP3 gene and the putative candidate gene sequence
was found between 21853801 – 21986473 bp. Linkage distance between this marker and
the gene Os ZIP 3 was calculated to be 48.9 cM. . The reported chromosomal position of
this gene in Nipponbare genome estimated in accordance to genetic markers assigned to
the BAC/PAC clones (as shown by TIGR genetic map) was 83.3 cM.
All the markers studied in the mapping experiment have shown a clear association
with the trait despite the less number of F2 sample analyzed. The mapping distances
obtained from this study were closer than the distances mapped according to the genetic
markers assigned to the BAC/PAC clones. Thus the mapping results strongly suggest the
strategy of identification of microsatellite markers in the vicinity of candidate genes
involved in the cat ion metabolism and their use in mapping to be very appropriate.
Description
Keywords
MAPPING, REGIONS, ASSOCIATED, IRON, CONTENT, RICE, GRAINS