Linkage mapping of QTLs for grain iron content and evaluation of PAU201 x Palman 579 (iron rich) segregating population(s) in rice (Oryza sativa L.)
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Date
2015
Authors
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Journal ISSN
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Publisher
CCSHAU
Abstract
Linkage mapping and marker assisted selection can greatly accelerate the efficacy of breeding
programs to improve mineral (iron and zinc) content in rice grains. A F2
population developed from the
cross between PAU201 (high yielding indica) and Palman 579 (iron rich indica) was used to map the
quantitative trait loci (QTL) associated with grain mineral content; the population consisted of 50 plants
displaying wide variation in grain mineral content. As many as 82/327 polymorphic microsatellite
(SSR) markers were used for linkage mapping. A total of 187 alleles and 18 new recombinant alleles
(different that those in parent rice varieties) were identified. NTSYS-pc based analysis (cluster tree
analysis, 2D-PCA and 3D-PCA) showed dispersion of the F2
population between the two distinct
parental genotypes. Composite interval mapping (CIM) analysis by WinQTL cartographer 2.5 revealed
a total of nineteen QTL for mineral content in grains on chromosome 2 and 10. Eight QTL for iron
content were mapped on chromosome 2 (qFE1, qFE2, qFE3, qFE4, qFE5, qFE6, qFE7 and qFE8 at
map positions 34.8, 54.2, 63.5, 70.0, 90.1, 152.1, 160.0 and 182.6 cM respectively) and four on
chromosome 10 (qFE9, qFE10 qFE11 and qFE12 at map positions 19.4, 37.4, 54.9 and 72.8 cM
respectively). Seven QTL for zinc content were mapped on chromosome 2 (qZN1, qZN2, qZn3 and
qZN4 at map positions 88.3, 93.6, 152.5 and 158.5 cM respectively) and chromosome 10 (qZN5, qZN6
and qZN7, at map positions 36.2, 45.5 and 53.8 respectively). A notable aspect of this study is that
QTL qFE5, qFE6 and qFE7 (90.1, 152.1 and 158.5 cM) for iron content and qZN1, qZN3 and qZN 4
(88.3, 152.5 and 158.5 cM) for zinc content on chromosome 2 are in close proximity, respectively, with
the same flanking markers. Similarly, on chromosome 10, qFE10 and qFE11 (37.3 and 54.9 cM) are in
close proximity of qZN5and qZN7 (36.2 and 53.8 cM), respectively, thus indicating that these QTL for
iron and zinc content may in fact be linked. PAU201/Palman 579 F
3
and F
4
populations were evaluated
for various agronomic traits and mineral content which displayed large variation for plant height (55.5
- 158.0 cm), effective number of tillers per plant (1 - 31), panicle length (15.2 - 30.6 cm), grain yield
per plant (1.6 - 66.6 g), 1000 grain weight (10.5 - 33.3 g) and grain length/breadth ratio (2.72 - 4.83),
Fe content (4.7 - 508.8 µg/g) and Zn content (1.2 - 130.4 µg/g) . Notably, nine F3
plants and eleven F
4
plants had iron content more than iron-rich donor parent, Palman 579. Grain iron content showed
significant positive correlation (r=0.829 and 0.335) with grain zinc content in both F
3
and F
4
populations indicating the feasibility of improving Fe and Zn levels simultaneously in rice grains. As
many as 50 promising F4 plants with grains rich in iron, zinc or both iron and zinc were selected for the
future breeding programs.
Description
Keywords
Oryza sativa, Mineral, Microsatellite (SSR) markers, QTL