Domesticated Emmer Research Articles

Genomic insights into the origin and evolution of spelt (Triticum spelta L.) as a valuable gene pool for modern wheat breeding

Spelt (Triticum aestivum ssp. spelta) is an important wheat subspecies mainly cultivated in Europe before the 20th century that has contributed to modern wheat breeding as a valuable genetic resource. However, relatively little is known about the origins and maintenance of spelt populations. Here, using resequencing data from 416 worldwide wheat accessions, including representative spelt wheat, we demonstrate that European spelt emerged when primitive hexaploid wheat spread to the west and hybridized with pre-settled domesticated emmer, the putative maternal donor. Genomic introgression regions from domesticated emmer confer spelt’s primitive morphological characters used for species taxonomy, such as tenacious glumes and later flowering. We propose a haplotype-based “spelt index” to identify spelt-type wheat varieties and to quantify utilization of the spelt gene pool in modern wheat cultivars. This study reveals the genetic basis for the establishment of the spelt wheat subspecies in a specific ecological niche and the vital role of the spelt gene pool as a unique germplasm resource in modern wheat breeding.

Molecular cytological analysis of alien introgressions in common wheat lines created by crossing of Triticum aestivum with T. dicoccoides and T. dicoccum.

Wild and domesticated emmer (ВВАА, 2n = 28) are of significant interest for expanding the genetic diversity of common wheat as sources of a high protein and microelement grain content, resistance to many biotic and abiotic factors. Particular interest in these species is also determined by their close relationship with Triticum aestivum L., which facilitates interspecific hybridization. The objective of this work was to analyze the nature of alien introgressions in hybrid lines from crossing common wheat varieties with T. dicoccoides and T. dicoccum, and to assess the effect of their genome fragments on the cytological stability of introgression lines. A C-banding technique and genotyping with SNP and SSR markers were used to determine localization and length of introgression fragments. Assessment of cytological stability was carried out on the basis of chromosome behavior in microsporogenesis. A molecular cytogenetic analysis of introgression wheat lines indicated that the inclusion of the genetic material of wild and domesticated emmer was carried out mainly in the form of whole arms or large fragments in the chromosomes of the B genome and less extended inserts in the A genome. At the same time, the highest frequency of introgressions of the emmer genome was observed in chromosomes 1A, 1B, 2B, and 3B. The analysis of the final stage of meiosis showed a high level of cytological stability in the vast majority of introgression wheat lines (meiotic index was 83.0-99.0 %), which ensures the formation of functional gametes in an amount sufficient for successful reproduction. These lines are of interest for the selection of promising material with agronomically valuable traits and their subsequent inclusion in the breeding process.

Genetic variation and genetic control of intraspikelet differences in grain weight and seed dormancy in wild and domesticated emmer wheats.

Seed dormancy, a vital strategy for wild plant species to adapt to an unpredictable environment in their natural habitats, was eliminated from cereals during the domestication process. Intraspikelet differences in grain size and seed dormancy have been observed in wild emmer wheat. To elucidate the genetic variation of these intraspikelet differences and to determine their genetic control, grain weight ratio (first florets/second florets) (GWR), germination rate, and germination index (GI) were analyzed in 67 wild and 82 domesticated emmer wheat accessions, as well as F1 hybrids, F2 populations, and F3-F6 populations derived from reciprocal crosses between wild and domesticated lines. Only the grains on the first florets of two-grained spikelets in wild accessions had varying degrees of dormancy with GI ranging from 0 to 1, which positively correlated with their GWR. This implies that wild emmer populations comprised genotypes with varying degrees of dormancy, including nondormant genotypes. According to segregations observed in F2 populations, the intraspikelet grain weight difference was controlled by two independently inherited loci. Furthermore, low-GWR populations with low or high GI values could be selected in F5 and F6 generations, implying that the major loci associated with dormancy might be independent of intraspikelet grain weight difference.

Changes in "natural antibiotic" metabolite composition during tetraploid wheat domestication

Gramineous plants protect their seeds from a variety of biotic stresses by producing toxic and deterrent secondary metabolites such as benzoxazinoids. It is unclear how the composition and abundance of these natural toxins has changed over the course of crop-plant domestication. To address this uncertainty, we characterized differences in metabolic levels of benzoxazinoids and their derivatives, between four lines of tetraploid wheat: wild emmer wheat (WEW), the direct progenitor of modern wheat; non-fragile domesticated emmer wheat (DEW), which was first domesticated about 11,000 years ago; the subsequently developed non-fragile and free-threshing durum landraces (LD); and modern durum (MD) varieties. Three-dimensional principal component analysis of mass spectrometry data of wheat metabolites showed with high resolution clear differences between metabolic profiles of WEW, DEW, and durum (LD + MD) and similarity in the metabolic profiles of the two durum lines (LD and MD) that is coherent with the phylogenetic relationship between the corresponding wheat lines. Moreover, our results indicated that some secondary metabolites involved in plant defense mechanisms became significantly more abundant during wheat domestication, while other defensive metabolites decreased or were lost. These metabolic changes reflect the beneficial or detrimental roles the corresponding metabolites might play during the domestication of three taxonomic subspecies of tetraploid wheat (Triticum turgidum).

CRISPR/Cas9 editing of wheat TaQ genes alters spike morphogenesis and grain threshability

The TaQ alleles as one of the AP2-like transcription factors in common wheat (Triticum aestivum) play an important role in the evolution of spike characteristics from wild and domesticated emmer to modern wheat cultivars. Its loss-of-function mutant not only changed threshability and spike architecture but also affected plant height, flowering time, and floret structure. However, the comprehensive functions of TaAQ and TaDq genes in wheat have not been fully elucidated yet. Here, CRISPR/SpCas9 was used to edit wheat TaAQ and TaDq. We obtained homozygous plants in the T1 generation with loss of function of only TaAQ or TaDq and simultaneous loss of function of TaAQ and TaDq to analyze the effect of these genes on wheat spikes and floret shapes. The results demonstrated that the TaAQ-edited plants and the TaAQ and TaDq simultaneously-edited plants were nearly similar in spike architecture, whereas the TaDq-edited plants were different from the wild-type ones only in plant height. Moreover, the TaAQ-edited plants or the TaAQ and TaDq simultaneously-edited plants were more brittle than the wild-type and the TaDq-edited plants. Based on the expression profiling, we postulated that the VRN1, FUL2, SEP2, SEP5, and SEP6 genes might affect the number of spikelets and florets per spike in wheat by regulating the expression of TaQ. Combining the results of this report and previous reports, we conceived a regulatory network of wheat traits, including plant height, spike shape, and floral organs, which were influenced by AP2-like family genes. The results achieved in this study will help us to understand the regulating mechanisms of TaAQ and TaDq alleles on wheat floral organs and inflorescence development.

Identification of a novel ERF gene, TaERF8, associated with plant height and yield in wheat

BackgroundEthylene Responsive Factor (ERF) is involved in various processes of plant development and stress responses. In wheat, several ERFs have been identified and their roles in mediating biotic or abiotic stresses have been elucidated. However, their effects on wheat plant architecture and yield-related traits remain poorly studied.ResultsIn this study, TaERF8, a new member of the ERF family, was isolated in wheat (Triticum aestivum L.). Three homoeologous TaERF8 genes, TaERF8-2A, TaERF8-2B and TaERF8-2D (named according to sub-genomic origin), were cloned from the common wheat cultivar Chinese Spring. The three homoeologs showed highly similar protein sequences, with identical AP2 domain. Whereas homoeologs sequence polymorphism analysis allowed the establishment of ten, two and three haplotypes, respectively. Expression analysis revealed that TaERF8s were constitutively expressed through entire wheat developmental stages. Analysis of related agronomic traits of TaERF8-2B overexpressing transgenic lines showed that TaERF8-2B plays a role in regulating plant architecture and yield-related traits. Association analysis between TaERF8-2B haplotypes (Hap-2B-1 and Hap-2B-2) and agronomic traits showed that TaERF8-2B was associated with plant height, heading date and 1000 kernel weight (TKW). The TaERF8-2B haplotypes distribution analysis revealed that Hap-2B-2 frequency increased in domesticated emmer wheat and modern varieties, being predominant in five major China wheat producing zones.ConclusionThese results indicated that TaERF8s are differentially involved in the regulation of wheat growth and development. Haplotype Hap-2B-2 was favored during domestication and in Chinese wheat breeding. Unveiling that the here described molecular marker TaERF8-2B-InDel could be used for marker-assisted selection, plant architecture and TKW improvement in wheat breeding.

A 3,000-year-old Egyptian emmer wheat genome reveals dispersal and domestication history.

Tetraploid emmer wheat (Triticum turgidum subsp. dicoccon) is a progenitor of the world’s most widely grown crop, hexaploid bread wheat (T. aestivum), as well as the direct ancestor of tetraploid durum wheat (T. turgidum subsp. turgidum). Emmer was one of the first cereals domesticated in the old world, cultivated from around 9700 BCE in the Levant1,2 and subsequently in South-Western Asia, Northern Africa, and Europe with the spread of Neolithic agriculture3,4. Here we report whole genome sequence from a museum specimen of Egyptian emmer wheat chaff, 14C-dated to the New Kingdom 1,130 – 1,000 BCE. Its genome shares haplotypes with modern domesticated emmer at shattering, seed size, and germination loci, and within other putative domestication loci, suggesting these traits share a common origin prior to emmer’s introduction to Egypt. Its genome is otherwise unusual, carrying haplotypes that are absent from modern emmer. Genetic similarity with modern Arabian and Indian emmer landraces connects ancient Egyptian emmer with early South-Eastern dispersals, while inferred gene flow with wild emmer from the Southern Levant signals a later connection. Our results show the importance of museum collections as sources of genetic data to uncover the history and diversity of ancient cereals.

Evaluation of grain dimension and weight using backcross recombinant inbred lines between wild and domesticated emmer wheat

Evaluation of grain dimension and weight using backcross recombinant inbred lines between wild and domesticated emmer wheat

Evolutionary history of the NAM-B1 gene in wild and domesticated tetraploid wheat

BackgroundThe NAM-B1 gene in wheat has for almost three decades been extensively studied and utilized in breeding programs because of its significant impact on grain protein and mineral content and pleiotropic effects on senescence rate and grain size. First detected in wild emmer wheat, the wild-type allele of the gene has been introgressed into durum and bread wheat. Later studies have, however, also found the presence of the wild-type allele in some domesticated subspecies. In this study we trace the evolutionary history of the NAM-B1 in tetraploid wheat species and evaluate it as a putative domestication gene.ResultsGenotyping of wild and landrace tetraploid accessions showed presence of only null alleles in durum. Domesticated emmer wheats contained both null alleles and the wild-type allele while wild emmers, with one exception, only carried the wild-type allele. One of the null alleles consists of a deletion that covers several 100 kb. The other null-allele, a one-basepair frame-shift insertion, likely arose among wild emmer. This allele was the target of a selective sweep, extending over several 100 kb.ConclusionsThe NAM-B1 gene fulfils some criteria for being a domestication gene by encoding a trait of domestication relevance (seed size) and is here shown to have been under positive selection. The presence of both wild-type and null alleles in domesticated emmer does, however, suggest the gene to be a diversification gene in this species. Further studies of genotype-environment interactions are needed to find out under what conditions selection on different NAM-B1 alleles have been beneficial.

The allelic distribution and variation analysis of the NAM-B1 gene in Chinese wheat cultivars

The NAM-B1 gene is a member of the NAC (NAM, ATAF, and CUC) transcription factor family and plays an important role in regulating wheat grain protein content (GPC). The ancestral NAM-B1 allele has been discovered in many tetraploid wild emmer (Triticum turgidum ssp. dicoccoides) accessions and few domesticated emmer accessions (T. turgidum ssp. dicoccum), however, it is rarely found in hexaploid bread wheat (Triticum aestivum L.). There are no systematic reports on the distribution of NAM-B1 alleles in Chinese wheat cultivars. In this study, the NAM-B1 alleles in 218 Chinese cultivars were investigated. The cultivars were collected from five major wheat regions (12 provinces), covering most of the winter wheat growing regions in China. The results showed that the NAM-B1 gene is present in 53 (24.3%) cultivars and absent in the remaining 165 (75.7%) cultivars. Further analysis revealed that in contrast to the wild-type allele, the NAM-B1 gene in Chinese wheat cultivars contained a 1-bp insertion in the coding region. This caused a frame-shift mutation and introduced a stop codon in the middle of the gene, rendering it non-functional. Polymorphisms were detected in DNA sequences of 21 cultivars among these 53 cultivars. However, cDNA sequence analysis suggested that these variations in the exon region were not able to restore NAM-B1 gene (1-bp insertion) function. Thus, exploring the distribution of NAM-B1 gene variations (1-bp insertion and deletion) can provide some information for improving the quality of winter wheat in China and other countries.

Using new morphological criteria to identify domesticated emmer wheat at the aceramic Neolithic site of Chogha Golan (Iran)

Reconstructing the domestication process of cereals is a basic requirement for the understanding of the Early Neolithic in the Near East and how agriculture emerged. Although there is general agreement on the criteria of differentiating wild from domesticated cereals, their application to material from aceramic Neolithic sites is problematic for reasons of preservation and diversity of early transitional chaff remains. In the present study we established an identification key for the distinction of wild and domestic emmer wheat (Triticum turgidum subsp. dicoccoides/dicoccum). General morphological analyses as well as experimental charring and measurements on wild and domestic emmer from the Fertile Crescent were conducted to track the main features that distinguish the two forms. Wild emmer can be differentiated from domestic emmer using longitudinal sections through rachises. The scar morphology of wild emmer specimens with a rough upper abscission scar is distinct from domestic emmer. In addition, two of the measuring tracks distinguish between domestic emmer and its progenitor. These results were applied to archaeological specimens from the aceramic Neolithic site of Chogha Golan (Ilam Province, Iran), which was excavated in 2009 and 2010 by a team of the Tübingen Iranian Stone Age Research Project. The carbonized emmer remains dating to about 9800BP comprise domestic-type and wild-type rachises, which is typical for cereal assemblages from aceramic Neolithic deposits.

Genotyping by sequencing transcriptomes in an evolutionary pre-breeding durum wheat population

The genetic diversity in durum wheat, Triticum turgidum durum, has been strongly reduced since the domestication of the wild Triticum turgidum dicoccoides. Monitoring durum wheat composite crosses incorporating related tetraploid taxa, such as wild and domesticated emmer wheat, is a suitable evolutionary pre-breeding method. Transcriptome sequencing paves the way for a genomic survey of single nucleotide polymorphisms (SNPs) segregating in such populations, offering the possibility of genotyping by sequencing to use these resources in genome-wide association studies (GWAS) and genomic selection (GS) programs. Evolutionary Pre-breeding pOpulation (EPO) is an evolutionary durum wheat pre-breeding population. Sequencing the transcriptome of 179 durum wheat lines (175 from EPO) led to the detection of 103,262 SNPs on two reference transcriptomes: one from the International Wheat Genome Sequencing Consortium and one assembled de novo on durum wheat. Using strict filtering to remove dubious heterozygous SNPs, EPO genetic diversity was eventually described with 76,188 high-confidence SNPs. The percentage of missing genotyping data depended on the expression level, and 88 individuals out of 175 were genotyped per SNP on average. Using the 3B pseudo-molecule of bread wheat, the transcription and diversity levels were shown to be higher in distal regions than in proximal regions, but SNPs were available throughout the chromosomes. Assuming good synteny with Hordeum, the trend was similar on the 14 chromosomes of the durum wheat genome. EPO hosts a high level of diversity, has a number of SNPs in low linkage disequilibrium (<40 Mb) and would be well suited for GWAS and GS programs.

Identification and molecular mapping of quantitative trait loci for Fusarium head blight resistance in emmer and durum wheat using a single nucleotide polymorphism-based linkage map

Fusarium head blight (FHB), caused by Fusarium graminearum, threatens durum wheat (Triticum turgidum subsp. durum) production in many durum-growing regions. It is critical to identify useful sources of FHB resistance for durum wheat. A domesticated emmer wheat (T. turgidum subsp. dicoccum) accession, PI 41025, was previously shown to be moderately resistant to FHB. This study aimed to identify quantitative trait loci (QTL) associated with FHB resistance in PI 41025. A population of 200 recombinant inbred lines were developed from a cross between the durum cultivar ‘Ben’ and PI 41025 and evaluated for reactions to F. graminearum in one field nursery and three greenhouse experiments. The disease severity data and a single nucleotide polymorphism marker-based linkage map from this population were used for QTL analysis. The results showed that one QTL on chromosome 2A from Ben and one QTL each on 3A and 5A from PI 41025 were associated with FHB resistance. The 2A and 3A QTL each explaining 8 % of the phenotypic variation were detected only in the greenhouse experiments. The QTL on 5A, which mapped near the domestication gene Q, explained 11 and 35 % of phenotypic variation in greenhouse and field evaluations, respectively. The identification of the 2A QTL from Ben confirmed the presence of FHB resistance in North Dakota durum cultivars, which have been successfully used for developing new cultivars with improved FHB tolerance. This study indicates that combining the QTL from related tetraploid species with native durum QTL will be useful for improving FHB resistance in durum.

Reticulated origin of domesticated emmer wheat supports a dynamic model for the emergence of agriculture in the fertile crescent.

We used supernetworks with datasets of nuclear gene sequences and novel markers detecting retrotransposon insertions in ribosomal DNA loci to reassess the evolutionary relationships among tetraploid wheats. We show that domesticated emmer has a reticulated genetic ancestry, sharing phylogenetic signals with wild populations from all parts of the wild range. The extent of the genetic reticulation cannot be explained by post-domestication gene flow between cultivated emmer and wild plants, and the phylogenetic relationships among tetraploid wheats are incompatible with simple linear descent of the domesticates from a single wild population. A more parsimonious explanation of the data is that domesticated emmer originates from a hybridized population of different wild lineages. The observed diversity and reticulation patterns indicate that wild emmer evolved in the southern Levant, and that the wild emmer populations in south-eastern Turkey and the Zagros Mountains are relatively recent reticulate descendants of a subset of the Levantine wild populations. Based on our results we propose a new model for the emergence of domesticated emmer. During a pre-domestication period, diverse wild populations were collected from a large area west of the Euphrates and cultivated in mixed stands. Within these cultivated stands, hybridization gave rise to lineages displaying reticulated genealogical relationships with their ancestral populations. Gradual movement of early farmers out of the Levant introduced the pre-domesticated reticulated lineages to the northern and eastern parts of the Fertile Crescent, giving rise to the local wild populations but also facilitating fixation of domestication traits. Our model is consistent with the protracted and dispersed transition to agriculture indicated by the archaeobotanical evidence, and also with previous genetic data affiliating domesticated emmer with the wild populations in southeast Turkey. Unlike other protracted models, we assume that humans played an intuitive role throughout the process.

Genetic Diversity and Population Structure of Tetraploid Wheats (Triticum turgidum L.) Estimated by SSR, DArT and Pedigree Data.

Levels of genetic diversity and population genetic structure of a collection of 230 accessions of seven tetraploid Triticum turgidum L. subspecies were investigated using six morphological, nine seed storage protein loci, 26 SSRs and 970 DArT markers. The genetic diversity of the morphological traits and seed storage proteins was always lower in the durum wheat compared to the wild and domesticated emmer. Using Bayesian clustering (K = 2), both of the sets of molecular markers distinguished the durum wheat cultivars from the other tetraploid subspecies, and two distinct subgroups were detected within the durum wheat subspecies, which is in agreement with their origin and year of release. The genetic diversity of morphological traits and seed storage proteins was always lower in the improved durum cultivars registered after 1990, than in the intermediate and older ones. This marked effect on diversity was not observed for molecular markers, where there was only a weak reduction. At K >2, the SSR markers showed a greater degree of resolution than for DArT, with their identification of a greater number of groups within each subspecies. Analysis of DArT marker differentiation between the wheat subspecies indicated outlier loci that are potentially linked to genes controlling some important agronomic traits. Among the 211 loci identified under selection, 109 markers were recently mapped, and some of these markers were clustered into specific regions on chromosome arms 2BL, 3BS and 4AL, where several genes/quantitative trait loci (QTLs) are involved in the domestication of tetraploid wheats, such as the tenacious glumes (Tg) and brittle rachis (Br) characteristics. On the basis of these results, it can be assumed that the population structure of the tetraploid wheat collection partially reflects the evolutionary history of Triticum turgidum L. subspecies and the genetic potential of landraces and wild accessions for the detection of unexplored alleles.

Evolution of tetraploid wheat based on variations in 5′ UTR regions of Ppd-A1: evidence of gene flow between emmer and timopheevi wheat

Previous study showed that tetraploid wheat was divided into two groups (Type AI and Type AII) based on sequences around Ppd-A1 gene (Takenaka and Kawahara in Theor Appl Genet 125(5):999–1014, 2012). That study focused on domesticated emmer wheat and used only 19 wild emmer wheats, so could not be clear the evolutional relationship between Type AI and Type AII. Here, a total of 669 accessions comprising 65 einkorn wheats, 185 wild emmer wheats, 107 hulled emmer wheats, 204 free-threshing (FT) emmer wheats, and 108 timopheevii wheats were studied by PCR assay and DNA sequencing for Type AI/AII. Type AII was an older type than Type AI because all einkorn accessions had Type AII. In wild emmer, Type AI was distributed in the northeast regions of its distribution and Type AII was found to be centered on Israel. A total of 37.4 % of hulled emmer accessions were Type AI, while 92.2 % of FT emmer accessions were Type AI. Differences in the proportion of Type AI/AII in domesticated emmer suggested a strong bottle-neck effect. We also found two MITE-like sequence deletion patterns from a part of Type AII accessions (dic-del and ara-del). Dic-del was found from only Israeli wild emmer accessions and ara-del was found from almost all timopheevii wheat accessions. Only three timopheevii accessions did not have ara-del, and one wild emmer accession and ten hulled emmer accessions had ara-del. These accessions suggested gene flow between emmer and timopheevii wheat.

N.I. Vavilov's theory of centres of diversity in the light of current understanding of wheat diversity, domestication and evolution

N.I. Vavilov hypothesized that the geographical centres of diversity of crops indicate their geographical centres of origin. Vavilov&amp;rsquo;s conclusions about the geographical origins of einkorn, durum and common wheat agree well with current population and molecular genetic studies when macro-geography is used but agree poorly when they are examined at higher resolution. We examined the causes of such disagreements for tetraploid emmer wheat and hexaploid common and club wheat. Molecular studies suggest that emmer was domesticated in the Diyarbakir region in south-eastern Turkey. Nucleotide diversity of wild emmer in the Diyarbakir region estimated earlier was compared with nucleotide diversity of wild and domesticated emmer across their distribution estimated here. Although domesticated emmer is only half as diverse as wild emmer, it is more diverse than the ancestral wild emmer population in the Diyarbakir region. Its centre of diversity is in the Mediterranean and does not coincide with the geographical centre of emmer origin. A similar disagreement exists in hexaploid wheat. Its centre of molecular diversity is in Turkey, which is west of the putative site of its origin in Transcaucasia and north-western Iran. It is shown that the primary cause of the disagreements between geographical centres of crop diversity and geographical centres of crop origin is gene flow from an ancestor subsequently to crop origin, which modifies the geographical pattern of crop diversity. When such gene flow takes place and when crop is domesticated in a peripheral population of the ancestor, the centre of crop diversity and the centre of crop origin are unlikely to coincide.

Domestication evolution, genetics and genomics in wheat

Domestication of plants and animals is the major factor underlying human civilization and is a gigantic evolutionary experiment of adaptation and speciation, generating incipient species. Wheat is one of the most important grain crops in the world, and consists mainly of two types: the hexaploid bread wheat (Triticum aestivum) accounting for about 95% of world wheat production, and the tetraploid durum wheat (T. durum) accounting for the other 5%. In this review, we summarize and discuss research on wheat domestication, mainly focusing on recent findings in genetics and genomics studies. T. aestivum originated from a cross between domesticated emmer wheat T. dicoccum and the goat grass Aegilops tauschii, most probably in the south and west of the Caspian Sea about 9,000 years ago. Wild emmer wheat has the same genome formula as durum wheat and has contributed two genomes to bread wheat, and is central to wheat domestication. Domestication has genetically not only transformed the brittle rachis, tenacious glume and non-free threshability, but also modified yield and yield components in wheat. Wheat domestication involves a limited number of chromosome regions, or domestication syndrome factors, though many relevant quantitative trait loci have been detected. On completion of the genome sequencing of diploid wild wheat (T. urartu or Ae. tauschii), domestication syndrome factors and other relevant genes could be isolated, and effects of wheat domestication could be determined. The achievements of domestication genetics and robust research programs in Triticeae genomics are of greatly help in conservation and exploitation of wheat germplasm and genetic improvement of wheat cultivars.

Genetic variation in domesticated emmer wheat (Triticum turgidum L.) in and around Abyssinian Highlands

Because of the huge morphological variations exhibited there, the Abyssinian Highlands (Ethiopia) are thought of as the secondary center of diversity of domesticated emmer wheat (Triticum turgidum L.). The genetic diversity in 88 domesticated emmer wheat accessions from Ethiopia and other regions was analyzed using DNA sequences of parts of four genes, Acc1-A, Pgk1-B, Waxy-A and Waxy-B, which are single-copy genes in nuclear DNA. The multilocus genotypes determined by analysis using Structure enabled the 88 accessions to be divided into four clusters. Each cluster included both hulled and free-threshing subspecies, and there was no clustering corresponding to specific subspecies. Both hulled and free-threshing emmer landraces in Ethiopia had several characteristic alleles, and the gene flow between them was shown to be limited. The genetic composition of Ethiopian landraces differed from that of emmer in other regions of the world. However, their nucleotide diversity was not as high as that of other emmer populations. The large morphological diversity in Ethiopian emmer landraces must have evolved from a limited genetic background.

Domesticated emmer wheat [T. turgidum L. subsp. dicoccon (Schrank) Thell.] as a source for improvement of zinc efficiency in durum wheat

Modern durum wheat (AABB) is more sensitive to zinc (Zn) deficiency than bread wheat (AABBDD). One strategy to increase productivity and expansion of durum wheat industry in Zn-deficient soils is to improve its ability to grow and yield in such soils. This ability is termed Zn efficiency. In a growth room experiment using soil culture, we assessed the potential of Triticum turgidum L. subsp. dicoccon (Shrank) Thell. (domesticated emmer wheat, AABB) as a genetic resource for further improvement of Zn efficiency in modern durum wheat. Twenty four accessions of domesticated emmer wheat, four durum landraces/cultivars, and two bread wheat cultivars/ advanced breeders lines of known Zn efficiency were tested under Zn deficiency and Zn sufficiency. Significant variation was observed among genotypes in Zn deficiency symptoms, dry matter production, shoot Zn concentration, shoot Zn content and Zn utilisation efficiency (physiological efficiency). We identified domesticated emmer wheat accessions with greater Zn efficiency than modern durum wheat and even bread wheat genotypes. These accessions could be used in breeding programs to improve Zn efficiency of durum wheat. The results suggest that Zn efficiency of durum or bread wheat is likely to be determined collectively by its progenitors.