A breeding strategy targeting the secondary gene pool of bread wheat: introgression from a synthetic hexaploid wheat
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Introgressing one-eighth of synthetic hexaploid wheat genome through a double top-cross plus a two-phase selection is an effective strategy to develop high-yielding wheat varieties.
The continued expansion of the world population and the likely onset of climate change combine to form a major crop breeding challenge. Genetic advances in most crop species to date have largely relied on recombination and reassortment within a relatively narrow gene pool. Here, we demonstrate an efficient wheat breeding strategy for improving yield potentials by introgression of multiple genomic regions of de novo synthesized wheat. The method relies on an initial double top-cross (DTC), in which one parent is synthetic hexaploid wheat (SHW), followed by a two-phase selection procedure. A genotypic analysis of three varieties (Shumai 580, Shumai 969 and Shumai 830) released from this program showed that each harbors a unique set of genomic regions inherited from the SHW parent. The first two varieties were generated from very small populations, whereas the third used a more conventional scale of selection since one of bread wheat parents was a pre-breeding material. The three varieties had remarkably enhanced yield potential compared to those developed by conventional breeding. A widely accepted consensus among crop breeders holds that introducing unadapted germplasm, such as landraces, as parents into a breeding program is a risky proposition, since the size of the breeding population required to overcome linkage drag becomes too daunting. However, the success of the proposed DTC strategy has demonstrated that novel variation harbored by SHWs can be accessed in a straightforward, effective manner. The strategy is in principle generalizable to any allopolyploid crop species where the identity of the progenitor species is known.
The authors thank Chi Yen and Junliang Yang (Sichuan Agricultural University) for suggestions on the use of synthetic wheat; Robert McIntosh (University of Sydney) and Robert Koebner (email@example.com) for revising the article; the International Wheat Genome Sequencing Consortium for providing pre-publication access to the RefSeq v1.0 assembly and its annotation; Jizeng Jia (Chinese Academy of Agricultural Sciences) for providing SNP flanking sequences; Peng Qin (Yunnan Agricultural University) for running trials in Yunnan province; and Qiuzhen Jia (Gansu Academy of Agricultural Sciences) for providing Chinese Puccinia striiformis. f. sp. tritici races. This research was financially supported by the Chinese Government National Key Research and Development Program (2016YFD0102000), the National Natural Science Foundation of China (31071420, 30700495, 31671689, 31071418, 30270804, 31601300 and 31661143007), the Sichuan Provincial Agricultural Department Innovative Research Team (wheat-10) and the Sichuan Province Science and Technology Department Crops Breeding Project (2016NYZ0030). MJH and Rothamsted Research is supported via the Designing Future Wheat project (BB/P016855/1) by the UK Biotechnology and Biological Sciences Research Council.
Author contribution statement
D.L, L.Q.Z., M.H. and Y.Z. designed the project; D.L., L.Q.Z., M.H., Z.W.Y, S.N., S.D., Z.H.Y., B.W., Y.Z., X.L., H.Z. and L.H. produced the new elite lines; L.B.Z., D.X., Q.L., W.C. and K.Z. performed the FISH and SDS-PAGE analyses, gene isolation and plant-type comparison. M.H, M.Y., Y.W., L.B.Z., A.L. and W.Y. performed the phenotypic and QTL analyses. M.H., D.L., J.W., M.C. and X.C. performed the SNP genotyping and statistical analyses. D.L., M.H., M.K., M.J.H. and L.M wrote the manuscript.
Compliance with ethical standards
Conflict of interest
On behalf of all authors, the corresponding author declares no competing financial interests.
- Börner A, Ogbonnaya FC, Röder MS, Rasheed A, Periyannan S, Lagudah ES (2015) Aegilops tauschii introgressions in wheat. In: Molnár-Láng M, Ceoloni C, Doležel J (eds) Alien introgression in wheat. Springer, Cham, pp 245–271Google Scholar
- Coghlan A (2006) Synthetic wheat offers hope to the world. New Scientist 2538Google Scholar
- Hao M, Li A, Shi T, Luo J, Zhang L, Zhang X, Ning S, Yuan Z, Zeng D, Kong X, Li X, Zheng H, Lan X, Zhang H, Zheng Y, Mao L, Liu D (2017) The abundance of homoeologue transcripts is disrupted by hybridization and is partially restored by genome doubling in synthetic hexaploid wheat. BMC Genom 18:149CrossRefGoogle Scholar
- Kihara H (1944) Discovery of the DD-analyser, one of the ancestors of Triticum vulgare. Agric Hortic 19:889–890Google Scholar
- Liu DC, Hao M, Li AL, Zhang LQ, Zheng YL, Mao L (2016) Allopolyploidy and interspecific hybridization for wheat improvement. In: Mason AS (ed) Polyploidy and hybridization for crop improvement. CRC Press, Cambridge, pp 27–52Google Scholar
- McFadden ES, Sears ER (1944) The artificial synthesis of Triticum spelta. Rec Genet Soc Am 13:26–27Google Scholar
- Mujeeb-Kazi A, Rosas V, Roldan S (1996) Conservation of the genetic variation of Triticum tauschii (Coss.) Schmalh. (Aegilops squarrosa auct. non L.) in synthetic hexaploid wheats (T. turgidum L. s. lat. × T. tauschii; 2n = 6x = 42, AABBDD) and its potential utilization for wheat improvement. Genet Resour Crop Evolut 43:129–134CrossRefGoogle Scholar
- Ogbonnaya FC, Abdalla OS, Mujeeb-Kazi A, Kazi AG, Xu SS, Gosman N, Lagudah ES, Bonnett D, Sorrells ME, Tsujimoto H (2013) Synthetic hexaploids: harnessing species of the primary gene pool for wheat improvement. In: Janick J (ed) Plant breeding reviews. Wiley, New York, pp 35–122CrossRefGoogle Scholar
- The Wheat Pro-Breeding Project, Crop Wild Relatives (CWR) (2011) Global Crop Diversity Trust (GCDT). http://www.cwrdiversity.org/partnership/wheat-pre-breeding-project/
- Xiao J, Li J, Grandillo S, Ahn SN, Yuan L, Tanksley SD, McCouch SR (1998) Identification of trait-improving quantitative trait loci alleles from a wild rice relative, Oryza rufipogon. Genetics 150:899–909Google Scholar