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Triticeae Genomics and Genetics 2012, Vol.3, No.2, 9
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24
http://tgg.sophiapublisher.com
9
A Letter Open Access
Meta-analysis of QTLs Involved in Pre-harvest Sprouting Tolerance and
Dormancy in Bread Wheat
Sandhya Tyagi , Pushpendra Kumar Gupta
Molecular Biology Laboratory, Department of Genetics and Plant Breeding, Ch. Charan Singh University, Meerut, 250004, India
Corresponding author email:
pkgupta36@gmail.com;
Authors
Triticeae Genomics and Genetics, 2012, Vol.3, No.2 doi: 10.5376/tgg.2012.03.0002
Received: 05 Apr., 2012
Accepted: 12 Apr., 2012
Published: 05 May, 2012
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.
Preferred citation for this article:
Tyagi and Gupta, 2012, Meta-analysis of QTLs Involved in Pre-harvest Sprouting Tolerance and Dormancy in Bread Wheat,
Triticeae Genomics and Genetics,
Vol.3, No.2 9-24 (doi: 10.5376/tgg.2012.03.0002)
Abstract
In common wheat, meta-analysis of quantitative trait loci (QTL) associated with pre-harvest sprouting tolerance (PHST)
and dormancy was carried out using results of 15 studies involving 15 different mapping populations. The study was restricted to
only four chromosomes including three chromosomes of homoeologous group 3 (3A, 3B and 3D) and the chromosome 4A, since
QTLs for PHST and dormancy on these four chromosomes were reported in several earlier studies, thus making these chromosomes
suitable for meta-QTL analysis. The software BioMercator 2.1 was used to build a consensus map, and QTLs were projected on to
this map for conducting meta-analysis. Using 36 of the 50 original QTLs, 8 meta-QTLs (MQTLs) were identified: 7 MQTLs were
located on chromosomes of homoeologous group 3 including 3A (2 MQTL), 3B (3 MQTL) and 3D (2 MQTL), 1 MQTL was located
on chromosome 4A. Confidence intervals (C.I.) for each of these 8 MQTLs were particularly narrow. The mapping information for
50 QTLs was also used for “overview” analysis to visualize important genomic regions carrying the MQTLs for PHST and dormancy.
Co-localizations between candidate genes for dormancy/PHST (
taVP1
and
TaGA20
-
ox1
) and MQTL positions appeared globally
significant, although these candidate genes deserve further investigation. Markers associated with 8 MQTLs identified during the
present study should prove helpful for introgression of tolerance against pre-harvest sprouting (PHS) into high yielding wheat
varieties through marker-assisted selection (MAS).
Keywords
Meta-analysis; Meta-QTL (MQTL); Pre-harvest sprouting tolerance (PHST); Dormancy; Wheat
Background
Pre-harvest sprouting (PHS) in common wheat (
Triticum
astivum
) is characterized by germination of grains in
physiologically mature spikes, if subjected to prolonged
wet weather conditions before harvest (Sharma et al.,
1994; Groos et al., 2002; Kulwal et al., 2011). It is
widely known that PHS leads to yield losses and
downgrading of grain and seed quality, thus limiting
their end use. It is also known that PHS is a complex
trait that is affected by several genetic and environmen-
tal cues. In many breeding programs, introgression of
grain dormancy is the primary target to improve
pre-harvest sprouting tolerance (PHST), since seed
dormancy is one of the important traits, which may
contribute to PHST in wheat. The parameters that
have been used as estimates of PHST and dormancy,
include germination index (GI), sprouting index (SI),
visually sprouted seed (VI), and Hegberg falling
number (FN) (Fofana et al., 2009; Imtiaz et al., 2008;
Munkvold et al., 2009; Rasul et al., 2009). The first
three of these parameters are negatively correlated and
the last one (FN) is positively correlated with
PHST/dormancy. It is also known that PHST is
associated with red grain color (GC) (Nilsson-Ehle,
1914; DePauw and McCaig, 1983; Groos et al., 2002;
Fofana et al., 2009), so that GC has also been used as
a genetic marker for resistance to PHS (Flintham,
2000), although rare PHS tolerant white-grained
wheat genotypes have been obtained both in nature
and in the progenies of experimental crosses.
In the past decade, with the availability of high-density
linkage maps and with the development of powerful
statistical tools for QTL analysis, a number of studies
have been conducted to study the genetics of PHST
and dormancy in bread wheat, so that these traits are
now known to be controlled by a large number of
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