Progress in tetraploid wheat breeding through the use of synthetic hexaploid amphiploids

Autophagy is an indispensable biological process and plays crucial roles in plant growth and plant responses to both biotic and abiotic stresses. This study systematically identified autophagy-related proteins (ATGs) in wheat and its diploid and tetraploid progenitors and investigated their genomic organization, structure characteristics, expression patterns, genetic variation, and regulation network. We identified a total of 77, 51, 29, and 30 ATGs in wheat, wild emmer, T. urartu and A. tauschii, respectively, and grouped them into 19 subfamilies. We found that these autophagy-related genes (ATGs) suffered various degrees of selection during the wheat’s domestication and breeding processes. The genetic variations in the promoter region of Ta2A_ATG8a were associated with differences in seed size, which might be artificially selected for during the domestication process of tetraploid wheat. Overexpression of TaVAMP727 improved the cold, drought, and salt stresses resistance of the transgenic Arabidopsis and wheat. It also promoted wheat heading by regulating the expression of most ATGs. Our findings demonstrate how ATGs regulate wheat plant development and improve abiotic stress resistance. The results presented here provide the basis for wheat breeding programs for selecting varieties of higher yield which are capable of growing in colder, drier, and saltier areas.

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Genetic diversity, distribution and domestication history of the neglected GGAtAt genepool of wheat

10.1101/2021.01.10.426084 ◽

2021 ◽

Author(s):

Ekaterina D. Badaeva ◽

Fedor A. Konovalov ◽

Helmut Knüpffer ◽

Agostino Fricano ◽

Alevtina S. Ruban ◽

...

Keyword(s):

Evolutionary History ◽

Chromosomal Rearrangements ◽

Tetraploid Wheat ◽

Wheat Breeding ◽

Intraspecific Diversity ◽

Wheat Improvement ◽

Comprehensive Survey ◽

History Of ◽

Diversity Sampling ◽

Wheat Wild Relatives

AbstractBackgroundWheat yields are stagnating around the world and new sources of genes for resistance or tolerances to abiotic traits are required. In this context, the tetraploid wheat wild relatives are among the key candidates for wheat improvement. Despite of its potential huge value for wheat breeding, the tetraploid GGAtAt genepool is largely neglected. Understanding the population structure, native distribution range, intraspecific variation of the entire tetraploid GGAtAt genepool and its domestication history would further its use for wheat improvement.ResultsWe report the first comprehensive survey of genomic and cytogenetic diversity sampling the full breadth and depth of the tetraploid GGAtAt genepool. We show that the extant GGAtAt genepool consists of three distinct lineages. We provide detailed insights into the cytogenetic composition of GGAtAt wheats, revealed group-, and population-specific markers and show that chromosomal rearrangements play an important role in intraspecific diversity of T. araraticum. We discuss the origin and domestication history of the GGAtAt lineages in the context of state-of-the-art archaeobotanical finds.ConclusionsWe shed new light on the complex evolutionary history of the GGAtAt wheat genepool. We provide the basis for an increased use of the GGAtAt wheat genepool for wheat improvement. The findings have implications for our understanding of the origins of agriculture in southwest Asia.

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Frequent numerical and structural chromosome changes in early generations of synthetic hexaploid wheat

Genome ◽

10.1139/gen-2021-0074 ◽

2021 ◽

Author(s):

Siyu Zhang ◽

Pei Du ◽

Xueying Lu ◽

Jiaxin Fang ◽

Jiaqi Wang ◽

...

Keyword(s):

Hexaploid Wheat ◽

Aegilops Tauschii ◽

Tetraploid Wheat ◽

Snp Markers ◽

Synthetic Hexaploid Wheat ◽

Chromosome Variation ◽

Metaphase Chromosomes ◽

Wheat Evolution ◽

Significant Difference ◽

Synthetic Hexaploid

Modern hexaploid wheat (Triticum aestivum L.; AABBDD) evolved from a hybrid of tetraploid wheat (closely related to Triticum turgidum L. ssp. durum (Desf.) Husn., AABB) and goatgrass (Aegilops tauschii Coss., DD). Variations in chromosome structure and ploidy played important roles in wheat evolution. How these variations occurred and their role in expanding the genetic diversity in modern wheat is mostly unknown. Synthetic hexaploid wheat (SHW) can be used to investigate chromosome variation that occurs during the early generations of existence. SHW lines derived by crossing durum wheat ‘Langdon’ with twelve Ae. tauschii accessions were analyzed using oligonucelotide probe multiplex fluorescence in situ hybridization (FISH) to metaphase chromosomes and SNP markers. Cluster analysis based on SNP markers categorized them into three groups. Among 702 plants from the S8 and S9 generations, 415 (59.12%) carried chromosome variations involving all 21 chromosomes but with different frequencies for each chromosome and sub-genome. Total chromosome variation frequencies varied between lines, but there was no significant difference among the three groups. The non-random chromosome variations in SHW lines detected in this research may be an indication that similar variations occurred in the early stages of wheat polyploidization and played important roles in wheat evolution.

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Increase in grain protein percentage in high-yielding common wheat breeding lines by genes from wild tetraploid wheat

Euphytica ◽

10.1007/bf00041478 ◽

1987 ◽

Vol 36 (2) ◽

pp. 353-359 ◽

Cited By ~ 27

Author(s):

A. A. Levy ◽

M. Feldman

Keyword(s):

Common Wheat ◽

Tetraploid Wheat ◽

Wheat Breeding ◽

Grain Protein ◽

Breeding Lines ◽

Protein Percentage

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Hybrid necrosis as a problem in handling hexaploid × tetraploid wheat crosses

The Journal of Agricultural Science ◽

10.1017/s0021859600028987 ◽

1980 ◽

Vol 94 (2) ◽

pp. 377-382 ◽

Cited By ~ 6

Author(s):

R. S. Gregory

Keyword(s):

Hexaploid Wheat ◽

Tetraploid Wheat ◽

Wheat Breeding ◽

Small Scale ◽

Hybrid Necrosis ◽

Agronomic Characters ◽

Wheat Varieties ◽

Hybrid Plants ◽

Plant Breeding Institute ◽

Selection For

SummaryA tetraploid wheat breeding programme was initiated at the Plant Breeding Institute in 1970. Hexaploid × tetraploid wheat crosses were expected to contribute to the improvement of the tetraploid wheats but severe hybrid necrosis caused the death of the pentaploid Fxhybrid plants in most crosses. The genotypes of tetraploid wheat selections derived from crosses involving Rampton Rivet, a non-carrier of Neu were determined by test crossing to hexaploid wheat varieties which were known to carry the Neim allele. Similarly, hexaploid wheat selections which did not carry Ne2 were identified from crosses involving Maris Ranger by test crossing to durum selections which carried the Nef allele. By the careful choice of one parent, hexaploid x tetraploid wheat crosses were then made which avoided the hybrid necrosis problem. Segregation of the Ne% gene was as expected but selection for agronomic characters appeared to favour the retention of the dominant allele of the Ne1gene. Nevertheless, test crossing on a relatively small scale still identified many non-carriers.

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100 Gy60Coγ-Ray Induced Novel Mutations in Tetraploid Wheat

The Scientific World JOURNAL ◽

10.1155/2014/725813 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Chuntao Yang ◽

Jianshu Zhu ◽

Yun Jiang ◽

Xiaolu Wang ◽

Mengxue Gu ◽

...

Keyword(s):

Molecular Weight ◽

Seed Germination ◽

Chinese Spring ◽

Germination Rate ◽

Tetraploid Wheat ◽

Wheat Breeding ◽

Glutenin Subunits ◽

Novel Mutations ◽

Meiotic Process ◽

Mother Cells

10 accessions of tetraploid wheat were radiated with 100 Gy60Coγ-ray. The germination energy, germination rate, special characters (secondary tillering, stalk with wax powder, and dwarf), meiotic process, and high-molecular-weight glutenin subunits (HMW-GSs) were observed. Different species has different radiation sensibility. With 1 seed germinated (5%),T. dicoccum(PI434999) is the most sensitive to this dose of radiation. With a seed germination rate of 35% and 40%, this dose also affectedT. polonicum(As304) andT. carthlicum(As293). Two mutant dwarf plants,T. turgidum(As2255) 253-10 andT. polonicum(As302) 224-14, were detected. Abnormal chromosome pairings were observed in pollen mother cells of bothT. dicoccoides(As835) 237-9 andT. dicoccoides(As838) 239-8 with HMW-GS 1Ax silent in seeds from them. Compared with the unirradiated seed ofT. polonicum(As304) CK, a novel HMW-GS was detected in seed ofT. polonicum(As304) 230-7 and its electrophoretic mobility was between 1By8 and 1Dy12 which were the HMW-GSs of Chinese Spring. These mutant materials would be resources for wheat breeding.

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A locus for sodium exclusion (Nax1), a trait for salt tolerance, mapped in durum wheat

Functional Plant Biology ◽

10.1071/fp04111 ◽

2004 ◽

Vol 31 (11) ◽

pp. 1105 ◽

Cited By ~ 142

Author(s):

Megan P. Lindsay ◽

Evans S. Lagudah ◽

Ray A. Hare ◽

Rana Munns

Keyword(s):

Salt Tolerance ◽

Durum Wheat ◽

Triticum Turgidum ◽

Tetraploid Wheat ◽

Triticum Aestivum L ◽

Wheat Breeding ◽

Lower Yield ◽

Diverse Backgrounds ◽

Salt Affected Soils ◽

Sodium Exclusion

Salinity affects durum wheat [Triticum turgidum L. ssp. durum (Desf.)] more than it affects bread wheat (Triticum aestivum L.), and results in lower yield for durum wheat cultivars grown on salt-affected soils. A novel source of salt tolerance in the form of a sodium exclusion trait, identified previously in a screen of tetraploid wheat germplasm, was mapped using a QTL approach. The trait, measured as low Na+ concentration in the leaf blade, was mapped on a population derived from a cross between the low Na+ landrace and the cultivar Tamaroi. The use of AFLP, RFLP and microsatellite markers identified a locus, named Nax1 (Na exclusion), on chromosome 2AL, which accounted for approximately 38% of the phenotypic variation in the mapping population. Markers linked to the Nax1 locus also associated closely with low Na+ progeny in a genetically unrelated population. A microsatellite marker closely linked to the Nax1 locus was validated in genetically diverse backgrounds, and proven to be useful for marker-assisted selection in a durum wheat breeding program.

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Yield, growth, canopy traits and photosynthesis in high-yielding, synthetic hexaploid-derived wheats cultivars compared with non-synthetic wheats

Crop and Pasture Science ◽

10.1071/cp16072 ◽

2017 ◽

Vol 68 (2) ◽

pp. 115 ◽

Cited By ~ 11

Author(s):

Yonglu Tang ◽

Xiaoli Wu ◽

Chaosu Li ◽

Wuyun Yang ◽

Mingbo Huang ◽

...

Keyword(s):

Dry Matter ◽

Grain Filling ◽

Wheat Breeding ◽

Physiological Parameters ◽

Potential Yield ◽

Dry Matter Partitioning ◽

Physiological Basis ◽

Synthetic Hexaploid ◽

Spad Readings ◽

Synthetic Cultivars

Continuous improvement of potential yield is one of the most important goals of wheat breeding. The introduction of synthetic hexaploid wheat (SHW) germplasm has broken the bottleneck in potential yield, taking wheat breeding in China’s Sichuan Basin to a new level. However, systematic research on the physiological basis of high-yielding, SHW-derived cultivars has lagged behind. In the present study, three SHW-derived, high-yielding cultivars and three typical, non-synthetic cultivars widely used in wheat production were chosen for a 5-year study. Post-anthesis canopy structure, rates of canopy apparent photosynthesis (CAP), attenuation during grain filling, dry matter partitioning and other physiological parameters were studied. The average yield of the SHW-derived cultivars was 9154 kg ha–1, which was 13.5% higher than that of the non-synthetic cultivars. The increased yield was due to increased biomass and/or increased harvest index (HI). SHW-derived cultivars had shorter but wider flag leaves, with length : width ratio <10. The basal angle and open angle were small at the beginning of anthesis, which gradually increased as grain-filling progressed; the SPAD readings of the flag leaf and penultimate leaf of the SHW-derived cultivars was significantly higher than that of the non-synthetic cultivars from anthesis to mid–late grainfill. The CAP values at anthesis and 20 days post-anthesis were significantly higher in the SHW-derived cultivars than in non-synthetic cultivars, in which the difference was most significant between 10 : 00 and 12 : 00. The dry matter partitioning at anthesis varied significantly among cultivars, and the stem and sheath proportion of the SHW-derived cultivars was larger than that of the non-synthetic cultivars. At maturation, the spike rachis and leaves of the SHW-derived cultivars accounted for significantly smaller proportions of the total aboveground dry weight. Accordingly, the grain proportion was increased by 1–4 percentage points. Yield components were closely related to measured physiological parameters; e.g. grain yield correlated positively with SPAD values (r = 0.960**) and negatively with the proportion of spike rachis at maturation (r = –0.946**). This indicated that a semi-compact plant morphology, with high SPAD readings and high CAP and greater HI, was the physiological basis of high yield in SHW-derived cultivars.

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High molecular weight glutenin gene diversity in Aegilops tauschii demonstrates unique origin of superior wheat quality

10.21203/rs.3.rs-230727/v1 ◽

2021 ◽

Cited By ~ 1

Author(s):

Emily Delorean ◽

LiangLiang Gao ◽

Jose Fausto Cervantes Lopez ◽

The Open Wild Wheat Consortium ◽

Brande Wulff ◽

...

Keyword(s):

Gene Diversity ◽

Aegilops Tauschii ◽

Tetraploid Wheat ◽

Wheat Breeding ◽

D Genome ◽

Breeding Programs ◽

Lineage 2 ◽

End Use ◽

Genomic Resource ◽

New Alleles

Abstract Central to the diversity of wheat products was the origin of hexaploid bread wheat, which added the D-genome of Aegilops tauschii to tetraploid wheat giving rise to superior dough properties in leavened breads. The polyploidization, however, imposed a genetic bottleneck, with only limited diversity introduced in the wheat D-subgenome. To understand genetic variants for quality, we sequenced 273 accessions spanning the known diversity of Ae. tauschii. We discovered 45 haplotypes in Glu-D1, a major determinant of quality, relative to the two predominant haplotypes in wheat. The wheat allele 2+12 was found in Ae. tauschii Lineage 2, the donor of the wheat D-subgenome. Conversely, the superior quality wheat allele 5+10 allele originated in Lineage 3, a recently characterized lineage of Ae. tauschii, showing a unique origin of this important allele. These two wheat alleles were also quite similar relative to the total observed molecular diversity in Ae. tauschii at Glu-D1. Ae. tauschii is thus a reservoir for unique Glu-D1 alleles and provides the genomic resource to begin utilizing new alleles for end-use quality improvement in wheat breeding programs.

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CIMMYT's use of synthetic hexaploid wheat in breeding for adaptation to rainfed environments globally.

Australian Journal of Agricultural Research ◽

10.1071/ar07223 ◽

2008 ◽

Vol 59 (5) ◽

pp. 461 ◽

Cited By ~ 30

Author(s):

J. Lage ◽

R. M. Trethowan

Keyword(s):

Hexaploid Wheat ◽

Wheat Breeding ◽

Trial Data ◽

Emmer Wheat ◽

Yield Potential ◽

Synthetic Hexaploid Wheat ◽

Interspecific Hybridisation ◽

Coefficient Of Parentage ◽

Yield Trial ◽

Synthetic Hexaploid

The International Maize and Wheat Improvement Center (CIMMYT) has had significant impact on wheat production in rainfed regions of the developing world. During the last decade, yield potential has increased in drought-prone areas partly due to the use of synthetic hexaploid wheat (SHW), produced through interspecific hybridisation of Triticum turgidum spp. and Aegilops tauschii, followed by chromosome doubling. The objectives of this study were to document the use of SHW in wheat breeding at CIMMYT and quantify its potential effect on global wheat adaptation. The first SHW-derived lines targetted at rainfed conditions appeared in the 5th Semi-Arid Wheat Yield Trial (SAWYT) representing 8% of the lines, increasing to 46% by the 15th SAWYT. During the same period the average coefficient of parentage of SHW in all synthetically derived crosses decreased from 75 to 19%. Average yield rank of genotypes across locations and years was used as a performance indicator of the SHW-derived lines in SAWYT 5–12. In the 5th SAWYT the average rank of the SHW-derived lines was 30 (out of 50) increasing to 25 by the 12th SAWYT. SAWYT 11 was the first trial to include SHW-derived lines bred exclusively for rainfed environments, using directed selection for drought tolerance. International trial data from SAWYT 11 and 12 showed that the SHW-derived line Vorobey was a top-performing line. Vorobey performed well across all environments compared with the best locally adapted check cultivar at each location; trial means ranged from 1 to 8 t/ha. To further exploit genetic diversity for adaptation to drought, SHW has been produced using emmer wheat (T. turgidum L. subsp. dicoccon) as the tetraploid parent. Yield trial data from Mexico show that SHW derivatives based on emmer wheat improved yield performance under drought compared with their drought-tolerant recurrent parents. The use of SHW in wheat breeding for rainfed environments at CIMMYT has increased significantly over the past 10–15 years and the performance and effect of the derived lines have improved with time.

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