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Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici ( Bgt ), is a globally devastating disease. Wild emmer wheat ( Triticum turgidum var. dicoccoides ) is a valuable genetic resource for improving disease resistance in common wheat. A powdery mildew resistance gene was transferred to hexaploid wheat line WE74 from wild emmer accession G-748-M. Genetic analysis revealed that the powdery mildew resistance in WE74 is controlled by a single dominant gene, herein temporarily designated MlWE74 . Bulked segregant analysis (BSA) and molecular mapping delimited MlWE74 to the terminal region of chromosome 2BS flanking by markers WGGBD412 and WGGBH346 within a genetic interval of 0.25 cM and corresponding to 799.9 kb genomic region in the Zavitan reference sequence. Sequence annotation revealed two phosphoglycerate mutase-like genes, an alpha/beta-hydrolases gene, and five NBS-LRR disease resistance genes that could serve as candidates for map-based cloning of MlWE74 . The geographical location analysis indicated that MlWE74 is mainly distributed in Rosh Pinna and Amirim regions, in the northern part of Israel, where environmental conditions are favorable to the occurrence of powdery mildew. Moreover, the co-segregated marker WGGBD425 is helpful in marker-assisted transfer of MlWE74 into elite cultivars.

Drought events or the combination of drought and heat conditions are expected to become more frequent due to global warming, and wheat yields may fall below their long-term average. One way to increase climate-resilience of modern high-yielding varieties is by their genetic improvement with beneficial alleles from crop wild relatives. In the present study, the effect of two beneficial QTLs introgressed from wild emmer wheat and incorporated in the three wheat varieties BarNir, Zahir and Uzan was studied under well-watered conditions and under drought stress using non-destructive High-throughput Phenotyping (HTP) throughout the life cycle in a single pot-experiment. Plants were daily imaged with RGB top and side view cameras and watered automatically. Further, at two time points, the quantum yield of photosystem II was measured with a top view FluorCam. The QTL carrying near isogenic lines (NILs) were compared with their corresponding parents by t-test for all non-invasively obtained traits and for the manually determined agronomic and yield parameters. Data quality of phenotypic traits (repeatability) in the controlled HTP experiment was above 85% throughout the life cycle and at maturity. Drought stress had a strong effect on growth in all wheat genotypes causing biomass reduction from 2% up to 70% at early and late points in the drought period, respectively. At maturity, the drought caused 47–55% decreases in yield-related traits grain weight, straw weight and total biomass and reduced TKW by 10%, while water use efficiency (WUE) increased under drought by 29%. The yield-enhancing effect of the introgressed QTLs under drought conditions that were previously demonstrated under field/screenhouse conditions in Israel, could be mostly confirmed in a greenhouse pot experiment using HTP. Daily precision phenotyping enabled to decipher the mode of action of the QTLs in the different genetic backgrounds throughout the entire wheat life cycle. Daily phenotyping allowed a precise determination of the timing and size of the QTLs effect (s) and further yielded information about which image-derived traits are informative at which developmental stage of wheat during the entire life cycle. Maximum height and estimated biovolume were reached about a week after heading, so experiments that only aim at exploring these traits would not need a longer observation period. To obtain information on different onset and progress of senescence, the CVa curves represented best the ongoing senescence of plants. The QTL on 7A in the BarNir background was found to improve yield under drought by increased biomass growth, a higher photosynthetic performance, a higher WUE and a “stay green effect.”

Significance The realized threats of global warming to biodiversity have catalyzed the search for a solution to protect and conserve extant plant genetic resources. Part of the solution, however, is dependent on the knowledge of how plant populations respond genetically to these threats, which is largely lacking. We conducted a unique genomic characterization of genetic responses in 10 wild emmer wheat populations in Israel that were sampled twice in 1980 and 2008. After the 28 y of global warming, these populations displayed elevated selection, reduced diversity and temporal divergence, and carried increased mutational burdens forward. However, some populations still showed the ability to acquire beneficial alleles for future adaptation. The patterns of genetic response to rainfall and temperature were complex., Global warming has been documented to threaten wild plants with strong selection pressures, but how plant populations respond genetically to the threats remains poorly understood. We characterized the genetic responses of 10 wild emmer wheat (Triticum dicoccoides Koern.; WEW) populations in Israel, sampling them in 1980 and again in 2008, through an exome capture analysis. It was found that these WEW populations were under elevated selection, displayed reduced diversity and temporal divergence, and carried increased mutational burdens forward. However, some populations still showed the ability to acquire beneficial alleles via selection or de novo mutation for future adaptation. Grouping populations with mean annual rainfall and temperature revealed significant differences in most of the 14 genetic estimates in either sampling year or over the 28 y. The patterns of genetic response to rainfall and temperature varied and were complex. In general, temperature groups displayed more temporal differences in genetic response than rainfall groups. The highest temperature group had more deleterious single nucleotide polymorphisms (dSNPs), higher nucleotide diversity, fewer selective sweeps, lower differentiation, and lower mutational burden. The least rainfall group had more dSNPs, higher nucleotide diversity, lower differentiation and higher mutational burden. These characterized genetic responses are significant, allowing not only for better understanding of evolutionary changes in the threatened populations, but also for realistic modeling of plant population adaptability and vulnerability to global warming.

PubMedID: 31203884 Wheat domestication was a milestone in the rise of agrarian societies in the Fertile Crescent. As opposed to the freely dispersing seeds of its tetraploid progenitor wild emmer, the hallmark trait of domesticated wheat is intact, harvestable spikes. During domestication, wheat acquired recessive loss-of-function mutations in the Brittle Rachis 1 genes, both in the A genome (BTR1-A) and B genome (BTR1-B). In this study, we probe the geographical provenances of these mutations via haplotype analyses of a collection of wild and domesticated accessions. Our results show that the precursor of the domesticated haplotype of BTR1-A was detected in 32% of the wild accessions gathered throughout the Levant, from central Israel to central Turkey. In contrast, the precursor of the domesticated haplotype of BTR1-B, which carries a distinct 11 bp deletion in the promoter region, was found in only 10% of the tested wild accessions, all from the Southern Levant. Moreover, we identified of a single wild emmer accession in Southern Levant that carries the progenitor haplotypes for both BTR1-A and BTR1-B genes. These observations suggest that at least part of the emmer domestication process occurred in Southern Levant, contrary to the widely held view that the northern part of the Fertile Crescent was the center of wheat domestication. © 2019 Elsevier B.V. United States-Israel Binational Science Foundation United States - Israel Binational Agricultural Research and Development Fund: IS-4829-15 Israel Science Foundation Israel Science Foundation: 1137/17 United States - Israel Binational Agricultural Research and Development Fund United States-Israel Binational Science Foundation: 2015409 Çukurova Üniversitesi: FBA-2017-7930 This research was funded by the United States – Israel Binational Science Foundation (BSF grant 2015409 ), the US-Israel Binational Agricultural Research and Development Fund (BARD project No. IS-4829-15 ), and the Israel Science Foundation (ISF grant 1137/17 ). HO acknowledges support from Çukurova University (FBA-2017-7930). Appendix A

There is an incessant need to address food security in staple crops, and the crop yield is positively correlated with grain weight. Grain size, determined by grain length and width, is an essential component of final grain weight in cereals. Wheat wild relatives are the goldmine to harness any trait of interest, including the component traits of grain size. It is crucial to understand the detailed mechanism of grain size formation and unravel underlying genes controlling grain size in these species for their proper utilization in wheat improvement. In this study, gene expression analysis was performed on developing grain in wild tetraploid progenitor Triticum dicoccoides (AABB) to identify candidate genes involved in determining grain size. Four T. dicoccoides accessions were selected, two (pau5228 and pau5322) with higher grain length and weight and two (pau14703 and pau14756) with comparatively smaller grains.Six genes out of the eight genes selected for expression study, viz., GL7, TaGL3, TaGS5, GS3, SRS3, and TaGASR7, were upregulated from 8 days post-anthesis (DPA) to 20 DPA in both the large grain accessions, while TaGW2 gene was upregulated in both small grain accessions. TGW6 was downregulated in all the accessions at all stages of grain development. The results indicated that the selected genes play an essential role in grain size formation by controlling individual morphometric components of grain length and width. Targeted introgression genes controlling grain size components will eventually aid in improving grains yield.

Wild emmer wheat (WEW), the tetraploid progenitor of durum and bread wheat, is a valuable genetic resource for resistance to powdery mildew fungal disease caused by Blumeria graminis f. sp. tritici (Bgt). PmG16 gene, derived from WEW, confers high resistance to most tested Bgt isolates. We mapped PmG16 to a 1.4 cM interval between the flanking markers uhw386 and uhw390 on Chromosome 7AL. Based on gene annotation of WEW reference genome Zavitan_V1, 34 predicted genes were identified within the ~3.48 Mb target region. Six genes were annotated as associated with disease resistance, of which TRIDC7AG077150.1 was found to be highly similar to Pm60, previously cloned from Triticum urartu and residing in the same syntenic region. A functional molecular marker (FMM) for Pm60 (M-Pm60-S1) co-segregated with PmG16, suggesting that WEW PmG16 is probably an orthologue of Pm60 from Triticum urartu (designated here as TdPm60). Sequence alignment identified only eight SNPs that differentiate between TdPm60 and TuPm60. Furthermore, our results suggest that other WEW powdery mildew resistance genes MlIW172 and MlIW72, that also mapped to the same region of Chromosome 7AL, might be identical or allelic to TdPm60. Screening of 230 WEW accessions with Pm60 specific markers, 58 resistant accessions were identified from Southern Levant harboring the TdPm60 allele, while all the susceptible accessions showed no PCR amplifications. Deployment of TdPm60 is clearly more advantageous over TuPm60 since it can be rapidly introgressed by classical breeding approaches into bread wheat genetic background.

Triticum turgidum and T. timopheevii are two tetraploid wheat species sharing T. urartu as a common ancestor, and domesticated accessions from both of these allopolyploids exhibit nonbrittle rachis (i.e., nonshattering spikes). We previously described the loss-of-function mutations in the Brittle Rachis 1 genes BTR1-A and BTR1-B in the A and B subgenomes, respectively, that are responsible for this most visible domestication trait in T. turgidum. Resequencing of a large panel of wild and domesticated T. turgidum accessions subsequently led to the identification of the two progenitor haplotypes of the btr1-A and btr1-B domesticated alleles. Here, we extended the haplotype analysis to other T. turgidum subspecies and to the BTR1 homologues in the related T. timopheevii species. Our results showed that all the domesticated wheat subspecies within T. turgidum share common BTR1-A and BTR1-B haplotypes, confirming their common origin. In T. timopheevii, however, we identified a novel loss-of-function btr1-A allele underlying a partially brittle spike phenotype. This novel recessive allele appeared fixed within the pool of domesticated Timopheev’s wheat but was also carried by one wild timopheevii accession exhibiting partial brittleness. The promoter region for BTR1-B could not be amplified in any T. timopheevii accessions with any T. turgidum primer combination, exemplifying the gene-level distance between the two species. Altogether, our results support the concept of independent domestication processes for the two polyploid, wheat-related species.

The destructive wheat powdery mildew disease is caused by the fungal pathogen Blumeria graminis f. sp. tritici (Bgt). PmG3M, derived from wild emmer wheat Triticum dicoccoides accession G305-3M, is a major gene providing a wide-spectrum resistance against Bgt. PmG3M was previously mapped to wheat chromosome 6B using an F6 recombinant inbred line (RIL) mapping population generated by crossing G305-3M with the susceptible T. durum wheat cultivar Langdon (LDN). In the current study, we aimed to explore the defense mechanisms conferred by PmG3M against Bgt. Histopathology of fungal development was characterized in artificially inoculated leaves of G305-3M, LDN, and homozygous RILs using fluorescence and light microscopy. G305-3M exhibited H2O2 accumulation typical of a hypersensitive response, which resulted in programmed cell death (PCD) in Bgt-penetrated epidermal cells, while LDN showed well-developed colonies without PCD. In addition, we observed a post-haustorial resistance mechanism that arrested the development of fungal feeding structures and pathogen growth in both G305-3M and resistant RIL, while LDN and a susceptible RIL displayed fully developed digitated haustoria and massive accumulation of fungal biomass. In contrast, both G305-3M and LDN exhibited callose deposition in attempt to prevent fungal invasion, supporting this as a mechanism of a basal defense response not associated with PmG3M resistance mechanism per se. The presented results shed light on the resistance mechanisms conferred by PmG3M against wheat powdery mildew.

The zinc/iron-regulated transporter-like protein (ZIP) family has a crucial role in Zn homeostasis of plants. Although the ZIP genes have been systematically studied in many plant species, the significance of this family in wild emmer wheat (Triticum turgidum ssp. dicoccoides) is not yet well understood. In this study, a genome-wide investigation of ZIPs genes based on the wild emmer reference genome was conducted, and 33 TdZIP genes were identified. Protein structure analysis revealed that TdZIP proteins had 1 to 13 transmembrane (TM) domains and most of them were predicted to be located on the plasma membrane. These TdZIPs can be classified into three clades in a phylogenetic tree. They were annotated as being involved in inorganic ion transport and metabolism. Cis-acting analysis showed that several elements were involved in hormone, stresses, grain-filling, and plant development. Expression pattern analysis indicated that TdZIP genes were highly expressed in different tissues. TdZIP genes showed different expression patterns in response to Zn deficiency and that 11 genes were significantly induced in either roots or both roots and shoots of Zn-deficient plants. Yeast complementation analysis showed that TdZIP1A-3, TdZIP6B-1, TdZIP6B-2, TdZIP7A-3, and TdZIP7B-2 have the capacity to transport Zn. Overexpression of TdZIP6B-1 in rice showed increased Zn concentration in roots compared with wild-type plants. The expression levels of TdZIP6B-1 in transgenic rice were upregulated in normal Zn concentration compared to that of no Zn. This work provides a comprehensive understanding of the ZIP gene family in wild emmer wheat and paves the way for future functional analysis and genetic improvement of Zn deficiency tolerance in wheat.

Fifteen full-length wheat grain avenin-like protein coding genes ( TaALP ) were identified on chromosome arms 7AS, 4AL, and 7DS of bread wheat with each containing five genes. Besides the a- and b-type ALPs, a c type was identified in the current paper. Both a and b types have two subunits, named x and y types. The five genes on each of the three chromosome arms consisted of two x-type genes, two y-type genes, and one c-type gene. The a-type genes were typically of 520 bp in length, whereas the b types were of 850 bp in length, and the c type was of 470 bp in length. The ALP gene transcript levels were significantly up-regulated in Blumeria graminis f. sp. tritici (Bgt) -infected wheat grain caryopsis at early grain filling. Wild emmer wheat [(WEW), Triticum dicoccoides ] populations were focused on in our paper to identify allelic variations of ALP genes and to study the influence of natural selection on certain alleles. Consequently, 25 alleles were identified for TdALP-bx-7AS , 13 alleles were identified for TdALP-ax-7AS , 7 alleles were identified for TdALP-ay-7AS , and 4 alleles were identified for TdALP-ax-4AL . Correlation studies on TdALP gene diversity and ecological stresses suggested that environmental factors contribute to the ALP polymorphism formation in WEW. Many allelic variants of ALPs in the endosperm of WEW are not present in bread wheat and therefore could be utilized in breeding bread wheat varieties for better quality and elite plant defense characteristics.

The seven plant species mentioned in the Bible describes the fertility of the Promised Land. These are: wheat, barley, the grapevine, the fig tree, the pomegranate tree, the olive tree and the date palm. They represent some of the earliest domesticated plants in the Middle East. They could serve as basic food all year round, because their fruits were easy to store. Olive oil, wine and fig fruit were also used for medicinal purposes. Contemporary knowledge confirms the exceptional nutritional value of these seven species, as well as their health-related benefits.

We demonstrate that Yr15, YrG303, and YrH52 resistances are encoded by the Wtk1 locus, but express variable resistance responses to yellow rust in a genetic background-dependent manner., The wild emmer wheat (Triticum turgidum ssp. dicoccoides; WEW) yellow (stripe) rust resistance genes Yr15, YrG303, and YrH52 were discovered in natural populations from different geographic locations. They all localize to chromosome 1B but were thought to be non-allelic based on differences in resistance response. We recently cloned Yr15 as a Wheat Tandem Kinase 1 (WTK1) and show here that these three resistance loci co-segregate in fine-mapping populations and share an identical full-length genomic sequence of functional Wtk1. Independent ethyl methanesulfonate (EMS)-mutagenized susceptible yrG303 and yrH52 lines carried single nucleotide mutations in Wtk1 that disrupted function. A comparison of the mutations for yr15, yrG303, and yrH52 mutants showed that while key conserved residues were intact, other conserved regions in critical kinase subdomains were frequently affected. Thus, we concluded that Yr15-, YrG303-, and YrH52-mediated resistances to yellow rust are encoded by a single locus, Wtk1. Introgression of Wtk1 into multiple genetic backgrounds resulted in variable phenotypic responses, confirming that Wtk1-mediated resistance is part of a complex immune response network. WEW natural populations subjected to natural selection and adaptation have potential to serve as a good source for evolutionary studies of different traits and multifaceted gene networks.

Heading date (HD) is an important agronomic trait, influencing directly or indirectly yield and quality traits. Previous experiments showed that the chromosome arm substitution line (CASL) 4AL of wild emmer in the background of Chinese Spring (CS) was about 18–22 days later in HD than CS. In this study, CASL4AL flowered roughly 20 days earlier than CS grown under long day (LD) with short day (SD) vernalization, but failed to flower when planted under controlled SD conditions. The above results suggest CASL4AL carries an extremely sensitive photoperiod response gene. CASL4AL showed a major difference from CS in restricted young spike development, remaining at the double-ridge stage and floret-primordium differentiation stage much longer than CS under SD. To map this gene, the F2 population from cross between CS and CASL4AL were explored in two consecutive years. In 2016, a HD related QTL flanked by M576 and wmc468 with a LOD score (8.5) was detected. In 2017, this QTL was repeatedly detected with a higher LOD score (10.03), and therefore named as QPpd.zafu-4A. A total of 27 genes were annotated and possible candidate was discussed. This work lays a foundation for map-based cloning of QPpd.zafu-4A and elucidating its molecular mechanism in affecting HD.

Genetic dissection of GPC and TKW in tetraploid durum × WEW RIL population, based on high-density SNP genetic map, revealed 12 GPC QTLs and 11 TKW QTLs, with favorable alleles for 11 and 5 QTLs, respectively, derived from WEW. Wild emmer wheat (Triticum turgidum ssp. dicoccoides, WEW) was shown to exhibit high grain protein content (GPC) and therefore possess a great potential for improvement of cultivated wheat nutritional value. Genetic dissection of thousand kernel weight (TKW) and grain protein content (GPC) was performed using a high-density genetic map constructed based on a recombinant inbred line (RIL) population derived from a cross between T. durum var. Svevo and WEW acc. Y12-3. Genotyping of 208 F6 RILs with a 15 K wheat single nucleotide polymorphism (SNP) array yielded 4166 polymorphic SNP markers, of which 1510 were designated as skeleton markers. A total map length of 2169 cM was obtained with an average distance of 1.5 cM between SNPs. A total of 12 GPC QTLs and 11 TKW QTLs were found under five different environments. No significant correlations were found between GPC and TKW across all environments. Four major GPC QTLs with favorable alleles from WEW were found on chromosomes 4BS, 5AS, 6BS and 7BL. The 6BS GPC QTL coincided with the physical position of the NAC transcription factor TtNAM-B1, underlying the cloned QTL, Gpc-B1. Comparisons of the physical intervals of the GPC QTLs described here with the results previously reported in other durum × WEW RIL population led to the discovery of seven novel GPC QTLs. Therefore, our research emphasizes the importance of GPC QTL dissection in diverse WEW accessions as a source of novel alleles for improvement of GPC in cultivated wheat.

BACKGROUND Wild emmer wheat could serve as a source of novel variation in grain quality and stress resistance for wheat breeding. A set of T. durum–T. dicoccoides chromosome substitution lines [LDN(DIC)] and the parental recipient cv. Langdon grown under contrasting water and nitrogen availability in the soil was examined in this study to identify differences in grain quality traits and dough rheological properties. RESULTS Significant genotypic variation was found among the materials for studied traits. This variation was also considerably affected by soil treatments and G-E interactions. The substitutions LDN(DIC-1A) and LDN(DIC-1B) showed separate differentiation in the composition of glutenin subunits. The results indicated that primarily chromosome DIC-6B is stable source of an enhanced grain protein content and advantageous dough rheological properties. Similar features seem to be shown by the substitutions with the DIC-1A, DIC-2A and DIC-6A, but not under nitrogen shortage, when generally a considerable decrease was noticed in the range of genotypic variation in grain quality. CONCLUSIONS The substitution lines, particularly those with DIC-6B and DIC-6A and to a lesser extent DIC-1A and DIC-2A, were distinguished by advantageous grain quality traits, mixing properties and dough functionality and appear to be the most promising sources of innovative genes for wheat breeding.

The modern cultivated wheat has passed a long evolution involving origin of wild emmer (WEM), development of cultivated emmer, formation of spelt wheat and finally establishment of modern bread wheat and durum wheat. During this evolutionary process, rapid alterations and sporadic changes in wheat genome took place, due to hybridization, polyploidization, domestication, and mutation. This has resulted in some modifications and a high level of gene loss. As a result, the modern cultivated wheat does not contain all genes of their progenitors. These lost genes are novel for modern wheat improvement. Exploring wild progenitor for genetic variation of important traits is directly beneficial for wheat breeding. WEM wheat (Triticum dicoccoides) is a great genetic resource with huge diversity for traits. Few genes and quantitative trait loci (QTL) for agronomic, quantitative, biotic and abiotic stress-related traits have already been mapped from WEM. This resource can be utilized for modern wheat improvement by integrating identified genes or QTLs through breeding.

Wild emmer, Triticum turgidum subsp. dicoccoides, is an annual tetraploid wheat characterized by a brittle spike axis that spontaneously disintegrates at maturity. It occurs widely in the so-called Fertile Crescent of the Near East and is of great importance for understanding wheat evolution and for breeding modern wheat cultivars tolerant of extreme heat and dryness. Wild emmer was first collected by Theodor Kotschy on Mt Hermon in Lebanon in 1855, but was not found again for more than half a century. Friedrich August Kornicke was first to realize that Kotschy's specimen represented an ancestral form of hexaploid bread wheat, T. aestivum, but, although he gave it a name, he did not describe it. Paul Ascherson and Paul Graebner were the first to provide a description, basing it on information received in a letter from Kornicke. In doing so, they validated Kornicke's suggested name T. sativum var. dicoccoides and made Kotschy's specimen the holotype. Five years later, on the basis of information received from Ascherson and Georg Schweinfurth in Berlin, Aaron Aaronsohn rediscovered wild emmer on Mt Hermon and started to send specimens for further study to Europe. Soon afterwards he also discovered it east of the river Jordan, while Theodor Strauss collected the first specimens in Iran. This paper focuses on the as yet widely unappreciated herbarium record, listing and commenting on early specimens collected in the wild as well as those cultivated in botanical gardens up to 1910.

Significance Wheat grain avenin-like proteins (ALPs) have functions for dough quality and antifungal activities. A genome-wide characterization of ALP encoding genes in bread wheat is conducted. Results showed that most ALPs are transcriptionally active in developing grains and are up-regulated upon Bgt infection. The allelic diversity of ALPs in 21 natural populations of wild emmer wheat (WEW) in Israel were studied. Many ALP allelic variations in WEW were associated with regional environmental adaption. Our findings demonstrate that the diversifying natural selection through climatic and edaphic factors was a major driving force for the allelic diversity of ALP genes. The results indicate that WEW harbors a high genetic diversity of ALPs utilizable for wheat improvement., Fifteen full-length wheat grain avenin-like protein coding genes (TaALP) were identified on chromosome arms 7AS, 4AL, and 7DS of bread wheat with each containing five genes. Besides the a- and b-type ALPs, a c type was identified in the current paper. Both a and b types have two subunits, named x and y types. The five genes on each of the three chromosome arms consisted of two x-type genes, two y-type genes, and one c-type gene. The a-type genes were typically of 520 bp in length, whereas the b types were of 850 bp in length, and the c type was of 470 bp in length. The ALP gene transcript levels were significantly up-regulated in Blumeria graminis f. sp. tritici (Bgt)-infected wheat grain caryopsis at early grain filling. Wild emmer wheat [(WEW), Triticum dicoccoides] populations were focused on in our paper to identify allelic variations of ALP genes and to study the influence of natural selection on certain alleles. Consequently, 25 alleles were identified for TdALP-bx-7AS, 13 alleles were identified for TdALP-ax-7AS, 7 alleles were identified for TdALP-ay-7AS, and 4 alleles were identified for TdALP-ax-4AL. Correlation studies on TdALP gene diversity and ecological stresses suggested that environmental factors contribute to the ALP polymorphism formation in WEW. Many allelic variants of ALPs in the endosperm of WEW are not present in bread wheat and therefore could be utilized in breeding bread wheat varieties for better quality and elite plant defense characteristics.

The biotroph wheat powdery mildew, Blumeria graminis (DC.) E.O. Speer, f. sp. tritici Em. Marchal (Bgt), has undergone long and dynamic co-evolution with its hosts. In the last 10,000 years, processes involved in plant evolution under domestication, altered host-population structure. Recently both virulence and genomic profiling separated Bgt into two groups based on their origin from domestic host and from wild emmer wheat. While most studies focused on the Bgt pathogen, there is significant knowledge gaps in the role of wheat host diversity in this specification. This study aimed to fill this gap by exploring qualitatively and also quantitatively the disease response of diverse host panel to powdery mildew [105 domesticated wheat genotypes (Triticum turgidum ssp. dicoccum, T. turgidum ssp. durum, and T. aestivum) and 241 accessions of its direct progenitor, wild emmer wheat (T. turgidum ssp. dicoccoides)]. A set of eight Bgt isolates, originally collected from domesticated and wild wheat was used for screening this wheat collection. The isolates from domesticated wheat elicited susceptible to moderate plant responses on domesticated wheat lines and high resistance on wild genotypes (51.7% of the tested lines were resistant). Isolates from wild emmer elicited reciprocal disease responses: high resistance of domesticated germplasm and high susceptibility of the wild material (their original host). Analysis of variance of the quantitative phenotypic responses showed a significant Isolates × Host species interaction [P(F) < 0.0001] and further supported these findings. Furthermore, analysis of the range of disease severity values showed that when the group of host genotypes was inoculated with Bgt isolate from the reciprocal host, coefficient of variation was significantly higher than when inoculated with its own isolates. This trend was attributed to the role of major resistance genes in the latter scenario (high proportion of complete resistance). By testing the association between disease severity and geographical distance from the source of inoculum, we have found higher susceptibility in wild emmer close to the source. Both qualitative and quantitative assays showed a reciprocal resistance pattern in the wheat host and are well aligned with the recent findings of significant differentiation into wild-emmer and domesticated-wheat populations in the pathogen.

Vitamin E is an essential human nutrient that was first isolated from wheat. Emmer wheat, the cereal of Old World agriculture and a precursor to durum wheat, grows wild in the Fertile Crescent. Evolution Canyon, Israel, provides a microsite that models effects of contrasting environments. The north-facing and south-facing slopes exhibit low and high stress environments, respectively. Wild emmer wheat seeds were collected from both slopes and seed tocochromanol contents measured to test the hypothesis that high stress alters emmer wheat seed tocol-omics. Seeds from high stress areas contained more total vitamin E (108±15 nmol/g) than seeds from low stress environments (80±17 nmol/g, P=.0004). Vitamin E profiles within samples from these different environments revealed significant differences in isoform concentrations. Within each region, β- plus γ-tocotrienols represented the highest concentration of wheat tocotrienols (high stress, P.0001; low stress, P.0001), while α-tocopherol represented the highest concentration of the tocopherols (high stress, P=.0002; low stress, P.0001). Percentages of both δ-tocotrienol and δ-tocopherol increased in high stress conditions. Changes under higher stress apparently are due to increased pathway flux toward more tocotrienol production. The production of more δ-isoforms suggests increased flow through a divergent path controlled by the VTE1 gene. Hence, stress conditions alter plant responses such that vitamin E profiles are changed, likely an attempt to provide additional antioxidant activity to promote seed viability and longevity.

The flowering in winter and wild wheats is induced by extended exposure to cold temperatures, a process called vernalization while spring wheats do not have any such requirement. In the present study, we analyzed 45 accessions of wild emmer wheat T. dicoccoides for the allelic composition of the vernalization genes at VRN-A1 and VRN-B1 loci. Three gene based markers for VRN-A1 and two for VRN-B1 locus were used. Thirty five T. dicoccoides accessions had only winter type allele vrn-A1 at VRN-A1 locus. One accession each had VRN-A1a and Vrn-A1d allele, and two accessions each showed the presence of VRN-A1b and Vrn-A1c, potent spring type alleles. Three accessions, however, had multiple alleles at VRN-A1 locus. At the VRN-B1 locus 35 accessions had winter type allele vrn-B1 and 10 accession had dominant Vrn-B1 allele. These T. dicoccoides accessions constitute a very useful resource for incorporation of alternative vernalization alleles in the cultivated wheat gene pool for developing better adaptive wheat varieties.

This study was conducted to revise the taxonomic identity and clarify specific relationships among the studied Triticum species in Egypt. The studied species included; T. dicoccum (Schrank) Schubl.; T. dicoccoides (Koren ex Asch. & Graebn.) Aaron Sohn. T. tugidum L.; T. durum Desf.; T. pyramidale (Delile ex Schult.) Percival and T. aestivum L. Moreover, the wild Emmer Wheat T. dicoccoides (Koren ex Asch. & Graebn.) Aaron Sohn was recently found in Egypt as a new record. The genus Triticum L. includes 14 species, all of them are cultivated for food except the wild Emmer.

Emmer wheat (Triticum turgidum ssp. dicoccum) was a principal crop in the development and spread of Neolithic agriculture in the Old World. It represents the primitive situation in the domestication of AABB tetraploid wheat. To understand the genetic modifications underlying the early stage of tetraploid wheat domestication, QTL analysis was carried out using 144 F2 plants derived from a cross between the domesticated emmer wheat and the wild emmer wheat (T. turgidum ssp. dicoccoides). To our knowledge, this is the first report of molecular linkage map and QTL analysis of the domestication-related characters in emmer wheat. The linkage map with a total length of 2849.8 cM was constructed using 227 microsatellite (SSR) markers. Chromosomal location and effect of QTLs were estimated for ten domestication-related traits including whole plant and spike characteristics. Seventeen QTLs were detected on chromosomes 1B, 2A, 2B, 3A, 3B, 4A, 5B, and 7B. Two regions on chromosomes 2A and 3B have a large effe...

Whole-genome scans with large number of genetic markers provide the opportunity to investigate local adaptation in natural populations and identify candidate genes under positive selection. In the present study, adaptation genetic differentiation associated with solar radiation was investigated using 695 polymorphic SNP markers in wild emmer wheat originated in a micro-site at Yehudiyya, Israel. The test involved two solar radiation niches: (1) sun, in-between trees; and (2) shade, under tree canopy, separated apart by a distance of 2–4 m. Analysis of molecular variance showed a small (0.53%) but significant portion of overall variation between the sun and shade micro-niches, indicating a non-ignorable genetic differentiation between sun and shade habitats. Fifty SNP markers showed a medium (0.05 ≤ FST ≤ 0.15) or high genetic differentiation (FST > 0.15). A total of 21 outlier loci under positive selection were identified by using four different FST-outlier testing algorithms. The markers and genome locations under positive selection are consistent with the known patterns of selection. These results suggested that genetic differentiation between sun and shade habitats is substantial, radiation-associated, and therefore ecologically determined. Hence, the results of this study reflected effects of natural selection through solar radiation on EST-related SNP genetic diversity, resulting presumably in different adaptive complexes at a micro-scale divergence. The present work highlights the evolutionary theory and application significance of solar radiation-driven natural selection in wheat improvement.

Wild emmer wheat, Triticum turgidum subsp. dicoccoides, (2n = 4x = 28; genome BBAA), the progenitor of domesticated wheat, is genetically very close to durum and common wheat. This wild taxon has many characteristics that would be valuable if transferred to domesticated wheat. An appropriate exploitation of the "wild" genome requires its dissection into segments and evaluation of the contribution of each segment separately to the performance of domesticated wheat. This work describes the production of a series of chromosome-arm substitution lines (CASLs) of wild emmer in the background of the Israeli common wheat cultivar Bethlehem (2n = 6x = 42; genome BBAADD). The identity of the "wild" arm in each CASL was confirmed through the use of RFLP and SSR markers that were polymorphic between the two taxa. The product of this work is a series of true-breeding agronomic lines the breeding value of which can be evaluated under field conditions in different geographic regions. The usefulness of CASLs in studying the improvement of qualitative and quantitative traits in wheat is discussed.

Triticum turgidum L. var. dicoccoides (DIC) provides a useful source of genes to improve agronomic and quality characteristics of durum wheat. Research was performed to identify DIC chromosomes that carry useful genes for quality improvement. Langdon-T. dicoccoides substitution lines consisting of 13 lines based on DIC accession PI 481521, 10 lines on PI 478742, and 2 lines on Israel A were evaluated for kernel characteristics and protein molecular weight distribution. DIC chromosomes 3A from PI 481521, and 1A and 7A from PI 478742 increased kernel hardness. Chromosome 2A from PI 481521 increased kernel weight, which resulted in increased semolina yield. Some substituted DIC chromosomes also affected grain protein concentration and protein molecular weight distribution. For example, chromosomes 2A, 5B, and 7B from PI 481521, and 6B from Israel A increased total protein concentration, which was primarily attributed to an increase of SDS soluble gliadins. Chromosome 6B from PI 478742 was unique in that it led to an increase in SDS insoluble high molecular weight polymeric proteins, which contributed to increased dough mixing strength. Results from this research indicated that chromosome 6B from PI 478742 is a potential gene source to improve dough characteristics of durum wheat by increasing insoluble high molecular weight polymeric protein concentration.

The transition from hunting and gathering to agriculture had revolutionary consequences for the development of human societies. Crops such as wheat, barley, lentil, pea and chickpea played a crucial role in the establishment of complex civilizations in south west Asia. Wild emmer wheat (Triticum dicoccoides) was one of the first cereals to be domesticated in the Fertile Crescent between c. 12,000 and c. 10,000 years ago. This step provided the key for subsequent bread wheat evolution. Wild emmer is found today in the western Fertile Crescent in Jordan, Syria and Israel, the central part of southeastern Turkey and mountain areas in eastern Iraq and western Iran. In this review, we summarize issues concerning geography and domestication of wild emmer wheat based on published molecular and archaeobotanical data and on our recent findings. We suggest that modern domestic tetraploid wheats derived from wild emmer lines from southeast Turkey. However, our understanding of emmer domestication is not complete. The “dispersed-specific” domestication model proposed for einkorn might well be appropriate also for emmer.

Triticum turgidum L. var. dicoccoides has been a useful source of genes for high grain protein content (GPC) in wheat. The objective of this study was to test the agronomic and quality characteristics of 23 durum Langdon–T. dicoccoides (LDN–DIC) substitutions based on T. dicoccoides accessions PI 481521 (LDN521) and PI 478742 (LDN742), with emphasis on finding new genes for high GPC. The 23 LDN–DIC substitutions and checks were grown in replicated yield trials at Fargo and Prosper, ND in 2005–2006. The lines were evaluated for grain yield, plant height, and heading date. Twelve quality traits, including GPC, were evaluated using standard methods. Potentially useful variation for thousand-kernel weight, kernel size, semolina extraction, and semolina brightness and color, was identified. Eight lines including LDN742-6B, LDN521-7B, LDN521-5B, LDN742-7A, LDN742-5B, LDN521-2A, LDN742-7B, and LDN521-1A had significantly higher GPC than LDN, suggesting that chromosomes 1A, 2A, 5B, and 7B of PI 481521 and 7A, 5B, 6B, and 7B of PI 478742 may carry high GPC genes. Using allele specific marker Xuhw89, LDN742-6B was shown to carry the same Gpc-B1 allele as in Israel A. The remaining six lines with high GPC are potential sources of new high GPC genes for durum wheat.

Disease resistance (R) genes are intriguing in their evolution and diversity patterns because of their constant interactions with evolving pathogens. In this study, we demonstrate the use of resistance gene analog (RGA) markers to estimate genetic diversity among 13 populations (118 genotypes) of Triticum dicoccoides collected along a natural aridity gradient in Israel. The diversity patterns of 204 markers derived from two R-gene domains, nucleotide binding site (NBS) and leucine-rich repeat (LRR), were compared and contrasted. Diversity patterns of NBS domain markers differed significantly from those of the LRR domain. NBS markers showed higher between-population diversity (Fst= 0.58), while LRR markers showed higher within-population diversity (Fst= 0.35). Gene diversity (He) values were twofold higher in the LRR domain than in the NBS domain (0.144 vs. 0.067). LRR Hevalues were correlated with precipitation in the spring (r = 0.8, p = 0.01), while NBS Hevalues showed no correlation with any ecogeographical variable. The evolutionary and applicative inferences of these findings are discussed. The current study demonstrates that RGA profiling is an excellent tool for studying diversity of R genes in natural plant populations.

The Aaronsohn-ITMI international conference was held 16-20 April 2007 in Tiberias (Israel) to celebrate the 100 year anniversary of the rediscovery of wild emmer wheat by Aaron Aaronsohn in Rosh Pinna, a few kilometers away from Tiberias. The workshop, attended by more than 110 participants from 22 countries, also provided an opportunity to discuss the latest developments in Triticeae genetics and genomics.

Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe, is a serious disease of wheat (Triticum spp.) worldwide. Host resistance has proven the most effective method of controlling FHB in common wheat (T. aestivum L, 2n = 6x = 42, genomes AABBDD). Progress in breeding for FHB resistance in durum wheat (T. turgidum L. ssp. durum, 2n = 4x = 28, genomes AABB), however, has been limited by a lack of resistance sources. Fortunately, durum wheat has a large number of tetraploid relatives, which represent a gene pool for improvement of FHB resistance in durum. The objective of this study was to search for sources of FHB resistance in wild emmer wheat [T. turgidum L. ssp. dicoccoides (Korn. ex Asch. & Graebner) Thell., 2n = 4x = 28, genomes AABB] (TDIC). We evaluated 416 accessions of wild emmer wheat for reaction to FHB using the point inoculation method in a greenhouse environment. Accessions exhibiting a low FHB disease rating in preliminary evaluations were retested in fully replicated experiments. Among the 416 accessions tested, there was wide variation in response to FHB, ranging from highly resistant to highly susceptible. Several accessions showed minimal disease development across two or more seasons and represent potential new sources to enhance resistance of durum wheat to FHB.

Introgression was detected within wild emmer wheat population in Jordan during the year 2000. Wild emmer wheat was found to occur in non-disturbed habitat, very close to cultivated durum wheat in northern parts of Jordan, and it was found in cultivated durum wheat in southern parts of Jordan. Random Amplified Polymorphic DNA (RAPD) test was constructed to assess natural introgression occurrence within wild emmer wheat population. Associated durum wheat land races from the vicinity of durum wheat fields were also collected. Shannon Diversity Index for wild emmer wheat populations was 0.46 and for durum wheat landraces was 0.45. The percentage of polymorphic loci for wild emmer wheat populations was 92.6. The close genetic distance between certain wild emmer wheat populations and durum wheat landraces provided proofs that massive introgression has occurred.

Wild emmer wheats (Triticum turgidum var. dicoccoides L.) are potentially valuable sources of leaf rust (Puccinia triticina Eriks.) and stem rust (Puccinia graminis f. sp. tritici Eriks. & Henn.) resistance in breeding both durum (T. turgidum var. durum L.) and common wheat (T. aestivum L.). In an extension of previous work, 11 rust resistant accessions of wild emmer wheat were crossed and backcrossed from two to five times to susceptible durum or common wheats. Genes for leaf or stem rust resistance were transferred singly into several susceptible genotypes. Backcross lines homozygous for resistance to leaf rust were tested with a set of either 9 or 10 leaf rust races and those homozygous for resistance to stem rust were tested with a set of either 10 or 13 stem rust races. The emmer wheats proved to carry a number of genes for resistance to each rust. In most cases, when a cross was made to a hexaploid wheat, resistance to both rusts was suppressed in the F1 seedlings, even when resistance was dominant in the tetraploids. Nevertheless, resistance was successfully transferred from several accessions to the hexaploids, indicating that suppressors on the A or B genome chromosomes were involved and segregation occurred for them. Rust resistance tended to decrease when it was transferred to another species, particularly hexaploid wheat. A number of lines carrying genes for either leaf rust or stem rust resistance were resistant to all races with which they were tested and have potential in wheat breeding. Key words: Emmer wheat, Triticum turgidum var. dicoccoides, stem rust, leaf rust, suppressors

Around 1910 Aaron Aaronsohn of the Jewish community in Ottoman Palestine became very well known both as botanical explorer and agricultural expert, especially on the semiarid regions of the Mediterranean basin and the United States. He attracted the attention of the scientific world through his rediscovery of the long-sought wild progenitor of emmer wheat. Based on his claim that wild emmer wheat, as well as other wild forms of domesticated plants, may serve as what is today known as “gene pools”, Aaronsohn formulated an agricultural vision for improvement of agricultural varieties and practices, particularly aimed at dry-land farming. Capitalizing on the wide reception of his assertions, both by American professional circles of the United States Department of Agriculture and by lay public there, Aaronsohn succeeded in recruiting financial support for founding a Jewish agricultural experiment station in Palestine. It was an institute registered in New York, and was the first American research station to o...

A study was designed to sample and characterize 12 populations of wild emmer wheat in Jordan at the high-molecular-weight (HMW) glutenin and allozyme levels. Data were collected and individual plants were sampled from 207 permanent sampling points in three central, three peripheral, and six marginal populations during all or part of a five-year study period. Patterns of variation, based on four HMW-glutenin and 36 allozyme loci, were used in characterizing these populations. Polymorphisms, based on HMW-glutenins and allozymes, decreased with increasing aridity of the collection site. A large portion of the HMW-glutenin(61.1%) and allozyme (62.7%) variant alleles were localized. Gene differentiation estimates, based on HMW-glutenins and allozymes among (60.8 and 65.8%, respectively) and within (39.2 and 34.2%, respectively) populations, were high and comparatively similar; however less variation was partitioned among the Jordanian populations when compared to populations in the more mesic parts of the Fert...

Wild emmer wheat, Triticum turgidum ssp. dicoccoides, the progenitor of most domesticated wheats, was discovered by Aaron Aaronsohn in 1906 in the Levant. The contribution of this discovery to the study of the cytogenetic structure and evolution of the wheats, to an understanding of the processes and site of their domestication and evolution under cultivation, and to the improvement of domesticated wheat is discussed.

Osmotic adjustment, accumulation of soluble saccharides, and photosynthetic gas exchange were studied in five durum wheat (Triticum turgidum L. var. durum) and one wild emmer wheat (Triticum turgidum L. var. dicoccoides) cultivars of contrasting drought tolerance and yield stability. Soil water contents (SWC) were 100, 31, 20, and 12 % of maximum capillary capacity. Under mild water stress (SWC 31 to 20 %), osmotic adjustment capacity and high accumulation of saccharides were found in cv. Cham1, a high yielding and drought tolerant cultivar, and in var. dicoccoides, while lowest values were noted in the durum wheat landraces Oued-Zenati and Jennah-Khotifa. Under more severe water stress (SWC 12 %), the cv. Cham1 maintained higher net photosynthetic rate (PN) than other genotypes. The observed changes in the ratio intercellular/ambient CO2 concentration (ci/ca) indicated that under mild and severe water stress, the decrease in PN was mainly due to stomatal and non-stomatal factors, respectively.

The germplasm base collection (BC) of wild emmer wheat,Triticum dicoccoides, from Jordan consists of over 2,000 accessions. Data on 10 quantitative and 8 qualitative traits were analyzed using multivariate statistical analysis procedures. A stratified and proportional sampling procedure was used to select 10 and 5% of the BC to form two core collections: CC10 and CC5, respectively. Phenotypic variation in the BC, as estimated by the phenotypic diversity index, hs,j, was unevenly distributed among accessions, among populations, and among ecogeographical regions. Moreover, its level differed significantly among and within quantitatively and qualitatively inherited traits. This characteristic led to successfully selecting a core collection which represents all levels of hierarchy in the base collection. Examination of the data for the same 18 traits in the BC, CC10, and CC5 indicated that CC10 and CC5 retained, on average, 86.0 and 74.3% of the variation in the BC, respectively. Percent discrete phenotypic classes, with frequency >0.10 (i.e., common widespread and common localized phenotypes). recovered in CC10 and CC5 were 79.6 and 51.5%, respectively. Results of hierarchical analyses of variance showed that percent contribution by traits to total variance in hs,j. estimates increased from 64.0% in the BC to 78.0% in CC10, and to 96.3% in CC5. Nevertheless, and as theoretically expected, CC10 was more efficient than CC5 in retaining the amount and composition of the variation originally found in the base collection.

Evaluation data on 17 morpho-agronomic traits for twelve populations of wild emmer wheat, Triticum dicoccoides, Korn. from central, peripheral, and marginal regions of its distribution in Jordan, were subjected to univariate, principal component, and canonical discriminant analyses. Interrelationships and adjustments in traits under study were used to identify genetic distances and spatial variation among and within these populations. Principal component analysis revealed that the interrelationships implied among traits, in the same principal component, were not the same among and within populations. This spatial variability in principal components reflects specific adaptation to, or interaction with, the environment. Three canonical variables explained 85.0% of total variation in these populations. Spikelet size, flag leaf width, and days to maturity were the most discriminating traits. Mahalanobis distances suggest that spatial distances are not indicative of genetic distances among and within central, peripheral, and marginal populations. A number of trait combinations arising through multilocus genetic association or developmental correlations, which are conserved by genetic linkage and natural selection, are readily available for wheat breeding and improvement.

Seedlings of 38 wild emmer derivatives, and a total of 53 advanced wheat varieties/lines introduced from the International Maize and Wheat Improvement Centre (CIMMYT) or other sources, Nepalese breeding lines and local cultivars were inoculated with 18 different yellow rust isolates to postulate yellow rust resistance genes (Yr). Many wild emmer wheat derivatives used were resistant to all isolates indicating the presence of undescribed genes. Some derivatives carried Yr9, Yr6 and/or YrSU. Genes Yr1, Yr2, Yr6, Yr7, Yr8, Yr15, YrSU and YrA+ are no longer effective in Nepal; Yr4, Yr5, Yr9, Yr10, YrSP and YrSD are still effective; the effectiveness of Yr3 remains unclear. This study shows that stripe rust resistance in seedling stage of most Nepalese cultivars and advanced materials is based on Yr9 with combinations of Yr2, Yr6, Yr7, and YrA+, of which only Yr9 is still effective in Nepal. In many countries Yr9 has lost its effectiveness. Therefore the introduction of new Yr-genes from wild emmer wheat in Nepalese cultivars is highly important.

Dispersed and tandemly repeating sequences of various types are the most polymorphic components of genomes, especially of eukaryotic genomes. The tandem repeats are also least stable due to frequent changes in the numbers of repeating units in the runs. One may associate this fluid type of genomic polymorphism with individual phenotypic variations and, perhaps, with fast adaptation to a changing environment. A “modulation (or fast adaptation) code” was suggested in 1989 (by the author) that attributed to tandem repeats the function of tuning gene expression by spontaneous changes in the copy numbers of the repeating elements associated with the gene, with subsequent selection. This potentially powerful mechanism of fast adaptation without any changes in the genes themselves was originally illustrated by only a few examples. Since then several researchers have developed similar thoughts, and numerous new supporting examples have appeared in the literature. The changes in copy numbers of tandem repeats are found to influence nearby gene expression. The variable runs of the repeats may, thus, serve as tuners of the gene expression in response to environmental pressures. The same mechanism could serve for differentiation (adaptation of individual cells to a changing cellular environment) and for gradual changes in quantitative traits.