Fine mapping of a preharvest sprouting QTL interval on chromosome 2B in white wheat
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Fine mapping by recombinant backcross populations revealed that a preharvest sprouting QTL on 2B contained two QTLs linked in coupling with different effects on the phenotype.
Wheat preharvest sprouting (PHS) occurs when grain germinates on the plant before harvest, resulting in reduced grain quality. Previous mapping of quantitative trait locus (QTL) revealed a major PHS QTL, QPhs.cnl-2B.1, located on chromosome 2B significant in 16 environments that explained from 5 to 31 % of the phenotypic variation. The objective of this project was to fine map the QPhs.cnl-2B.1 interval. Fine mapping was carried out in recombinant backcross populations (BC1F4 and BC1F5) that were developed by backcrossing selected doubled haploids to a recurrent parent and self-pollinating the BC1F4 and BC1F5 generations. In each generation, three markers in the QPhs.cnl-2B.1 interval were used to screen for recombinants. Fine mapping revealed that the QPhs.cnl-2B.1 interval contained two PHS QTLs linked in coupling. The distal PHS QTL, located between Wmc453c and Barc55, contributed 8 % of the phenotypic variation and also co-located with a major seed dormancy QTL determined by germination index. The proximal PHS QTL, between Wmc474 and CNL415-rCDPK, contributed 16 % of the variation. Several candidate genes including Mg-chelatase H subunit family protein, GTP-binding protein and calmodulin/Ca2+-dependent protein kinase were linked to the PHS QTL. Although many recombinant lines were identified, the lack of polymorphism for markers in the QTL interval prevented the localization of the recombination breakpoints and identification of the gene underlying the phenotype.
We thank Drs. Pawan Kulwal and Long-Xi Yu for providing helpful comments on this study. Funding for this research was provided by USDA–NIFA National Research Initiative CAP Grant No. 2005-05130 and by Hatch 149-402.
Conflict of Interest
The authors declare that they have no conflict of interest.
The authors declare that the experiments described in this manuscript comply with the current laws of the United States.
- Brenchley R, Spannagl M, Pfeiffer M, Barker GLA, D’Amore R, Allen AM, McKenzie N, Kramer M, Kerhornou A, Bolser DKS, Waite D, Trick MBI, Gu Y, Huo N, Luo M-C, Sehgal S, Gill B, Kianian S, Anderson O, Kersey P, Dvorak J, McCombie WR, Hall A, Mayer MFX, Hall N, Edwards KJ, Bevan MW, Hall N (2012) Analysis of the bread wheat genome using whole-genome shotgun sequencing. Nature 491:705–710PubMedCentralCrossRefPubMedGoogle Scholar
- Kulwal PL, Mir RR, Kumar S, Gupta PK (2010) QTL analysis and molecular breeding for seed dormancy and pre-harvest sprouting tolerance in bread wheat. J Plant Biol 37:59–74Google Scholar
- Liu S, Sehgal SK, Li J, Lin M, Trick HN, Yu J, Gill BS, Bai G (2013) Cloning and characterization of a critical regulator for pre-harvest sprouting in wheat. Genetics 195:263–273Google Scholar
- Oh K, Hardeman K, Ivanchenko MG, Ellard-Ivey M, Nebenfuhr A, White TJ, Lomax TL (2002) Fine mapping in tomato using microsynteny with the Arabidopsis genome: the Diageotropica (Dgt) locus. Genome Biol 3:research0049–research0049.11Google Scholar
- Sakai H, Lee SS, Tanaka T, Numa H, Kim J, Kawahara Y, Wakimoto H, Yang C–C, Iwamoto M, Abe T, Yamada Y, Muto A, Inokuchi H, Ikemura T, Matsumoto T, Sasaki T, Itoh T (2013) Rice Annotation Project Database (RAP-DB): an integrative and interactive database for rice genomics. Plant Cell Physiol 54:e6PubMedCentralCrossRefPubMedGoogle Scholar