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BMC Plant Biol. 2012; 12: 9.
Published online Jan 17, 2012. doi:  10.1186/1471-2229-12-9
PMCID: PMC3287966
Integration of gene-based markers in a pearl millet genetic map for identification of candidate genes underlying drought tolerance quantitative trait loci
Deepmala Sehgal,1 Vengaldas Rajaram,2 Ian Peter Armstead,1 Vincent Vadez,2 Yash Pal Yadav,3 Charles Thomas Hash,2 and Rattan Singh Yadavcorresponding author1
1Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion SY23 3 EB, UK
2International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), ICRISAT-Patencheru, Hyderabad 502 324, Andhra Pradesh, India
3Chaudhary Charan Singh Haryana Agricultural University (CCSHAU), Bawal 123 501, Haryana, India
corresponding authorCorresponding author.
Deepmala Sehgal: des/at/aber.ac.uk; Vengaldas Rajaram: V.RAJARAM/at/CGIAR.ORG; Ian Peter Armstead: ipa/at/aber.ac.uk; Vincent Vadez: V.VADEZ/at/CGIAR.ORG; Yash Pal Yadav: yashpalydv/at/rediffmail.com; Charles Thomas Hash: C.HASH/at/CGIAR.ORG; Rattan Singh Yadav: rsy/at/aber.ac.uk
Received September 16, 2011; Accepted January 17, 2012.
Abstract
Background
Identification of genes underlying drought tolerance (DT) quantitative trait loci (QTLs) will facilitate understanding of molecular mechanisms of drought tolerance, and also will accelerate genetic improvement of pearl millet through marker-assisted selection. We report a map based on genes with assigned functional roles in plant adaptation to drought and other abiotic stresses and demonstrate its use in identifying candidate genes underlying a major DT-QTL.
Results
Seventy five single nucleotide polymorphism (SNP) and conserved intron spanning primer (CISP) markers were developed from available expressed sequence tags (ESTs) using four genotypes, H 77/833-2, PRLT 2/89-33, ICMR 01029 and ICMR 01004, representing parents of two mapping populations. A total of 228 SNPs were obtained from 30.5 kb sequenced region resulting in a SNP frequency of 1/134 bp. The positions of major pearl millet linkage group (LG) 2 DT-QTLs (reported from crosses H 77/833-2 × PRLT 2/89-33 and 841B × 863B) were added to the present consensus function map which identified 18 genes, coding for PSI reaction center subunit III, PHYC, actin, alanine glyoxylate aminotransferase, uridylate kinase, acyl-CoA oxidase, dipeptidyl peptidase IV, MADS-box, serine/threonine protein kinase, ubiquitin conjugating enzyme, zinc finger C- × 8-C × 5-C × 3-H type, Hd3, acetyl CoA carboxylase, chlorophyll a/b binding protein, photolyase, protein phosphatase1 regulatory subunit SDS22 and two hypothetical proteins, co-mapping in this DT-QTL interval. Many of these candidate genes were found to have significant association with QTLs of grain yield, flowering time and leaf rolling under drought stress conditions.
Conclusions
We have exploited available pearl millet EST sequences to generate a mapped resource of seventy five new gene-based markers for pearl millet and demonstrated its use in identifying candidate genes underlying a major DT-QTL in this species. The reported gene-based markers represent an important resource for identification of candidate genes for other mapped abiotic stress QTLs in pearl millet. They also provide a resource for initiating association studies using candidate genes and also for comparing the structure and function of distantly related plant genomes such as other Poaceae members.
Keywords: CISP, Candidate genes, Drought tolerance QTLs, EST-SSR, Pearl millet, SNP
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