Triticum Species Research Articles

Cytogenetic analysis of meiotic behaviour and stability in a trigeneric hybrid (triticale x trigopiro).

Trigeneric hybrids in Triticeae may help to establish evolutionary relationships among different genomes present in the same cellular genetic background and to transfer different alien characters into cultivated wheat. In the present study, a trigeneric hybrid involving species of Triticum, Secale, and Thinopyrum was synthesized by crossing hexaploid triticale with hexaploid trigopiro. The meiotic behaviour of chromosomes belonging to different genomes was analyzed, using routine and in situ hybridization techniques in F1, F2, and F3 generations of the trigeneric hybrid. The purpose of this study was to determine the chromosome number and genomic constitution and to discuss the mechanisms involved in the stabilization of the artificial tricepiro hybrids. The chromosome number of the trigeneric F1 hybrid was 2n = 42. Between 12 and 16 bivalents were observed in the central zone of the equatorial meiotic plate and between 9 and 18 univalents were found in the periphery of the MI equatorial plate. Seven of these univalents showed hybridization signals with rye DNA. Lagging rye and non-rye chromosomes and separation of sister chromatids were found in anaphase I. Tetrads with a maximum of six micronuclei, with and without hybridization signals of rye DNA, were observed. After three generations, meiotic cells revealed the presence of 42 chromosomes and 21 bivalents in diakinesis cells. The presence of 14 rye (Secale cereale) chromosomes and the complete pairing of chromosomes in F3 hybrids suggest that rye chromosomes would be preferentially transmitted to the progeny and that an elimination mechanism would act on chromosomes of Thinopyrum and wheat D genome.

Phylogenetic Analysis of Wall-Associated Kinase Genes in Triticum Species and Characterization of TaWAK7 Involved in Wheat Powdery Mildew Resistance.

Wall-associated kinases (WAKs), a group of receptor-like kinases, have been found to play important roles in defending against pathogens and in various developmental processes. However, the importance of this family in wheat remains largely unknown. Wheat powdery mildew is caused by Blumeria graminis f. sp. tritici (Bgt), which initiates infection on the cell surface and forms haustoria inside the cell; therefore, the defense to Bgt involves extracellular and subsequently intracellular signals. In this study, WAKs were identified genome-wide and analyzed phylogenetically, and then a transmembrane WAK gene that putatively participated in pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity to Bgt was functionally and evolutionarily investigated. In total, 1,193 WAKs were identified from wheat and its Gramineae relatives. Phylogenetic analysis indicated that WAKs expanded through tandem duplication or segment duplication. TaWAK7, from chromosome 2A, was identified as a Bgt-inducible gene both in susceptible and resistant materials, but it showed distinct responsive patterns. Functional analysis showed that TaWAK7 was involved in both the basal and resistance gene-mediated resistances. The specific gene structures and protein characteristics of TaWAK7, along with its orthologs, were characterized both in subgenomes of Triticum spp. and in the A genome of multiple wheat accessions, which revealed that TaWAK7 orthologs underwent complex evolution with frequent gene fusion and domain deletion. In addition, three cytoplasmic proteins interacting with TaWAK7 were indicated by yeast two-hybrid and bimolecular fluorescence complementation assays. Binding of TaWAK7 with these proteins could change its subcellular localization from the plasma membrane to the cytoplasm. This study provides a better understanding of the evolution of WAKs at the genomic level and TaWAK7 at the gene level and provides useful clues for further investigation of how WAKs transmit the extracellular signals to the cytoplasm to activate defense responses.

Diploid Triticum species as a potential source of resistance to powdery mildew

Mączniak prawdziwy jest jedną z najważniejszych chorób grzybowych roślin zbożowych. Powoduje obniżenie plonu i jakości zbieranego ziarna. Jednym z najlepszych sposobówochrony roślin przed mączniakiem jest wprowadzenie do odmian uprawnych efektywnych genów odporności. W niniejszej pracy przeprowadzono screening diploidalnych gatunków z rodzaju Triticum pod kątem identyfikacji potencjalnych źródeł genetycznej odporności na mączniaka. Spośród analizowanych form zidentyfikowano 21 genotypów, które wykazywały pełną odporność na wszystkie 3 zastosowane izolaty mączniaka. Cztery z nich należą do gatunku T. urartu, 12 do T. monococcum i 4 do T. boeoticum. Badania przedstawione w niniejszej pracy wykazały, że każdy z badanych gatunków może być źródłem genów odporności na mączniaka prawdziwego. Ponadto najbardziej odporne genotypy zidentyfikowano wśród form z Libanu i Syrii. Najniższy poziom odporności wykazałygenotypy z Turcji, co wskazuje, że obszar ten nie jest regionem o dużej presji tego patogena.

Investigation of media for wheat (Triticum aestivum L.) immature embryo culture

Immature embryos of F1 progeny resulting from taxonomically wide hybridizations require tissue culture using complex media to mature, grow and develop into normal and healthy plants. To gain insight as to how progeny of wide-crosses between wild and domestic Triticum species, 12 domestic varieties (Al-Eiz, Babel, Bedhaa, Entisar, Hadbaa, IPA 99, Latifia, Nour, Rabia, Sally, Sham 6, Tamoz 2) were used to determine the genotype response to culture media type. Immature embryos the aforementioned wheat varieties were screened on four media (Murashige and Skoog; MS full strength, ½ strength MS, Gamborg B-5; B-5 full strength, and ½ strength B-5) to determine performance when used as a female in a cross with wild species. The experiment used a completely randomized design with six replications. Traits recorded were final germinations percentage (FGP), shoot length (SL), root length (RL), and root number (RN). Results indicated significant variety x media interaction for all traits studied. Despite the interaction, in a practical sense, all varieties performed adequately on ½ B-5 and varieties Al-Eiz, Entisar, Hadbaa, and Latifia performed well on any of the four media. Tamoz 2 behaved recalcitrantly on all media tested. Data from this study indicated genetic variability among these wheat varieties caused substantial differences in response to each type of media.

Investigating Metabolic Plant Response toward Deoxynivalenol Accumulation in Four Winter Cereals.

Deoxynivalenol (DON) is a phytotoxic agent supporting the spread of fungal diseases in cereals worldwide, i.e., fusarium head blight. It is known that DON accumulation may elicit changes in plant secondary metabolites in response to pathogen attack. This study maps the changes in selected secondary metabolite classes upon DON contamination occurring in fifteen Triticum spp. genotypes, among them emmer, spelt, and soft wheat, and 2 tritordeum varieties, cultivated in two different sites and over two harvest years. The main phenolic classes (i.e., alkylresorcinols, soluble, and cell-wall bound phenolic acids) were targeted analyzed, while changes in the lipidome signature were collected through untargeted HRMS experiments. The results, obtained across multiple Triticum species and in open fields, confirmed the modulation of first-line biological pathways already described in previous studies involving single cereal species or a limited germplasm, thus reinforcing the involvement of nonspecific chemical defenses in the plant response to pathogen attack.

Allelic diversity of the Vrn genes and the control of growth habit and earliness in wheat.

Wheat is one of three main food crops around the world, which has the largest distribution area due to its adaptation to the different environments. This review considers polymorphisms and allelic variation of the vernalization response genes Vrn controlling the major adaptation traits in wheats (the genus Triticum L.): growth habit (spring vs. winter) and length of vegetative period (earliness). The review summarizes available information on the allelic diversity of the Vrn genes and discusses molecular-level relationships between Vrn polymorphisms and their effect on growth habit (spring vs. winter) and earliness (length vegetative period in spring plants) in di-, tetra- and hexaploid wheat species. A unique attempt has been made to relate information on mutations (polymorphisms) in dominant Vrn alleles to the values of the commercially most important trait "length of plant vegetative period (earliness)". The effects of mutations (polymorphisms) in the recessive vrn genes on vernalization requirement in winter wheats are considered, and this trait was formalized. The evolution of the winter/spring growth habit in the genus Triticum species is discussed. A scheme of phylogenetic interactions between Vrn alleles was constructed on the basis of these polymorphisms; the paper considers the possibilities to enhance the diversity of polymorphisms for the dominant Vrn genes and their alleles using wheat related species and rarely used alleles and discusses the prospects of breeding for improved earliness for concrete agroecological zones.

Phytochemical profile and anti-inflammatory activity of the hull of γ-irradiated wheat mutant lines (Triticum aestivum L.).

Wheat (Triticum aestivum Linn.; Poaceae) is the second most cultivated food crop among all global cereal crop production. The high carbohydrate content of its grains provides energy, multiple nutrients, and dietary fiber. After threshing, a substantial amount of wheat hull is produced, which serves as the non-food component of wheat. For the valorization of these by-products as a new resource from which functional components can be extracted, the hull from the seeds of cultivated wheat mutant lines bred after γ-irradiation were collected. Untargeted metabolite analysis of the hull of the original cultivar (a crossbreeding cultivar., Woori-mil × D-7) and its 983 mutant lines were conducted using ultra-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry technique. A total of 55 molecules were tentatively identified, including 21 compounds found in the Triticum species for the first time and 13 compounds not previously described. Among them, seven flavonolignans with a diastereomeric structure, isolated as a single compound from the hull of T. aestivum in our previous study, were used as the standards in the metabolite analysis. The differences in their collision cross-section values were shown to contribute to the clear distinction between tricine-lignan stereoisomers. To select functionally active agents with anti-inflammatory activity among the identified compounds, the wheat hull samples were evaluated for their inhibitory effect on nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 cells. As a result of multivariate analysis based on the results of chemical and biological profiles of the wheat hull samples, 10 metabolites were identified as key markers, contributing to the distinction between active and inactive mutant lines. Considering that one of the four key markers attributed to anti-inflammatory activity has been identified to be a flavonolignan, the wheat hull could be a valuable source of diverse tricin-lignan type compounds and used as a natural health-promoting product in food supplements.

Evolutionary genetics of wheat mitochondrial genomes

The Triticum-Aegilops complex provides ideal models for the study of polyploidization, and mitochondrial genomes (mtDNA) can be used to trace cytoplasmic inheritance and energy production following polyploidization. In this study, gapless mitochondrial genomes for 19 accessions of five Triticum or Aegilops species were assembled. Comparative genomics confirmed that the BB-genome progenitor donated mtDNA to tetraploid T. turgidum (genome formula AABB), and that this mtDNA was then passed on to the hexaploid T. aestivum (AABBDD). T urartu (AA) was the paternal parent of T. timopheevii (AAGG), and an earlier Ae. tauschii (DD) was the maternal parent of Ae. cylindrica (CCDD). Genic sequences were highly conserved within species, but frequent rearrangements and nuclear or chloroplast DNA insertions occurred during speciation. Four highly variable mitochondrial genes (atp6, cob, nad6, and nad9) were established as marker genes for Triticum and Aegilops species identification. The BB/GG-specific atp6 and cob genes, which were imported from the nuclear genome, could facilitate identification of their diploid progenitors. Genic haplotypes and repeat-sequence patterns indicated that BB was much closer to GG than to Ae. speltoides (SS). These findings provide novel insights into the polyploid evolution of the Triticum/Aegilops complex from the perspective of mtDNA, advancing understanding of energy supply and adaptation in wheat species.

Valorizing Traditional Greek Wheat Varieties: Phylogenetic Profile and Biochemical Analysis of Their Nutritional Value

Research has highlighted the nutritional benefits of ancient grains, especially emmer (Triticum turgidum ssp. dicoccum) and einkorn (Triticum monococcum), compared to modern varieties of common and durum wheat, focusing on their higher levels of antioxidants and phytochemicals. In this study, grains from old Greek landraces of einkorn, emmer, durum and common wheat were compared to modern wheat cultivars, as well as barley, oats and rye grains, to investigate their unique genetic profile and nutritional properties. Genotyping of Triticum species was performed using SSR markers, which allowed differentiation up to cultivar level. Nutritional factors like the total content of bound and free polyphenols, flavonoids, antioxidant activity and fatty acid profile were assessed. The results showed that emmer and einkorn had the highest total polyphenol, flavonoid and mono-unsaturated fatty acids content, as well as higher antioxidant activity than common and durum wheat. Local landraces of common and durum wheat also exhibited higher values than commercial cultivars. The results of this study demonstrate the high nutritional value of ancient wheat varieties. Many of these cultivars have been put aside by more productive, yet with lower qualitative characteristics, commercial cultivars, underlining the importance of maintaining sustainable agricultural practices to ensure their continued cultivation.

Carotenoids and tocols comparison in different Subspecies of Triticum turgidum and aestivum

Carotenoids and Tocols in six genotypes of Triticum turgidum ssp. durum, five of Triticum turgidum ssp. dicoccum, four of Triticum aestivum ssp. aestivum, and six of Triticum aestivum ssp. spelta were investigated. The aim of the present study was to identify, quantify, and compare the content of tocopherols, tocotrienols, and carotenoids in different primitive and modern genotypes of wheat species in order to evaluate the lines with the highest content and possibly use them for selection and breeding programs. The Triticum durum group showed the highest mean content of total carotenoids, with lutein being the most abundant, accounting for 80.12 % (Triticum spelta) to 86.65 % (Triticum turgidum) of total carotenoids. Among the genotypes, Line 6 (Triticum durum) had the highest lutein content (12.17 μg g−1), significantly differing from the lines within its group and the other groups of dicoccum, aestivum, and spelta.Triticum dicoccum exhibited a lower average content of total tocols compared to other Triticum species. The tocols profile showed a prevalence of tocotrienols over tocopherols. β + γ-T3 was the most abundant individual tocol isomer in all Triticum genotypes, contributing for 50.40 % (Triticum ssp. aestivum) and 42.50 % (Triticum spelta) of the total content, respectively. The highest β + γ-T3 content (23.83 μg/g) was found in Line 6 of Triticum durum. Correlation, principal component, and cluster analyses revealed positive correlations between total tocols and β/γ tocotrienols, significant differences between various groups of the same species, formation of six clusters labeled as I to VI, and the identification of genotypes from the same species grouped in different clusters.

PHENOTYPIC VARIABILITY EVALUATION OF WHEAT VARIETIES FROM THE SUCEAVA GENE BANK COLLECTION

The intensity of selection, inadvertent pathways of domestication, and the influence of climate change collectively amplify the frequency of detrimental alleles. This phenomenon, in turn, triggers genetic drift, leading to an in-advertent decline in the diversity of plant genetic resources. Genetic variability is of utmost importance for a species’ adaptability and overall fitness. Our investigation centres on Triticum germplasm within the agroclimatic conditions of the Suceava Gene Bank, encompassing 2021–2022 field trials. Comprehensive morphophysiological characterisation was conducted across 200 cultivated varieties, spanning three Triticum species (T. aestivum, T. turgidum and T. monococcum). Initially, the data underwent meticulous processing involving the computation of amplitude of variation, variance (s2), standard deviation (√s), and coefficients of variation (s%) for three pivotal agronomical traits: plant height, spikelets per spike, and total seeds per spike. Furthermore, an extensive cluster analysis was performed, encompassing multiple vital plant descriptors. The findings unveiled a remarkable dispersion of data, with standard deviation, amplitude of variation, and coefficient of variation collectively indicating substantial variability among the cultivated varieties. Within the same population, an intriguing observation emerged; of the 200 genotypes analysed, 83 exhibited immunity to Septoria tritici. Delving deeper into the statistical analysis, we identified two primary clusters within the population. Overall, a significant proportion of this germplasm showcased elevated phenotype scores, rendering them well-suited for further exploration as foundational material in pre-breeding initiatives.

Genomic content of wheat has a higher influence than plant domestication status on the ability to interact with Pseudomonas plant growth-promoting rhizobacteria.

Plant evolutionary history has had profound effects on belowground traits, which is likely to have impacted the ability to interact with microorganisms, but consequences on root colonization and gene expression by plant growth-promoting rhizobacteria (PGPR) remain poorly understood. Here, we tested the hypothesis that wheat genomic content and domestication are key factors determining the capacity for PGPR interaction. Thus, 331 wheat representatives from eight Triticum or Aegilops species were inoculated under standardized conditions with the generalist PGPR Pseudomonas ogarae F113, using an autofluorescent reporter system for monitoring F113 colonization and expression of phl genes coding for the auxinic inducing signal 2,4-diacetylphloroglucinol. The interaction with P. ogarae F113 was influenced by ploidy level, presence of genomes AA, BB, DD, and domestication. While root colonization was higher for hexaploid and tetraploid species, and phl expression level higher for hexaploid wheat, the diploid Ae. tauschii displayed higher phl induction rate (i.e., expression:colonisation ratio) on roots. However, a better potential of interaction with F113 (i.e., under non-stress gnotobiotic conditions) did not translate, after seed inoculation, into better performance of wheat landraces in non-sterile soil under drought. Overall, results showed that domestication and especially plant genomic content modulate the PGPR interaction potential of wheats.

Characterization of 14 Triticum species for the NAM-B1 gene and its associated traits.

Wheat grain protein, zinc (Zn), and iron (Fe) content are important wheat qualities crucial for human nutrition and health worldwide. Increasing these three components simultaneously in wheat grains by a single gene came into the picture through NAM-B1 cloning. NAM-B1 gene and its association with the mentioned grain quality traits have been primarily studied in common and durum wheat and their progenitors T. dicoccum and T. dicoccoides. In the present study, for the first time, 38 wheat accessions comprising ten hexaploids from five species and 28 tetraploids from nine species were evaluated in the field for two consecutive years. Additionally, the 582 first nucleotides of the NAM-B1 gene were examined. The NAM-B1 gene was present in 21 tetraploids and five hexaploid accessions. Seven tetraploid accessions contained the wild-type allele (five T. dicoccum, one T. dicoccoides, and one T. ispahanicum) and fourteen the mutated allele with a 'T' insertion at position 11 in the open reading frame, causing a frameshift. In hexaploid wheat comprising the gene, only one accession of T. spelta contained the wild-type allele, and the rest resembled the insertion mutated type. In the two-year field experiment, eight accessions with the wild-type NAM-B1 allele had significantly higher protein, Zn and Fe grain content when compared to indel-type accessions. Additionally, these accessions exhibited a lower mean for seed-filling duration than all other accessions containing indel-type alleles. In terms of grain yield, 1,000-kernel weight, kernel diameter, and kernel length, T. dicoccum accessions having wild-type alleles were similar to the indel-type accessions over two years of evaluation. These findings further support the possibility of simultaneous improvement of wheat grain protein, Zn, and Fe content by a single gene crucial for human nutrition and health worldwide.

Investigation of genetic diversity of Iranian wild relatives of bread wheat using ISSR and SSR markers

BackgroundWild relatives of wheat are one of the most important genetic resources to use in wheat breeding programs. Therefore, identifying wild relatives of wheat and being aware of their diversity, is undeniably effective in expanding the richness of the gene pool and the genetic base of new cultivars and can be a useful tool for breeders in the future. The present study was performed to evaluate the molecular diversity among 49 accessions of the genera Aegilops and Triticum in the National Plant Gene Bank of Iran using two DNA-based markers, i.e., SSR and ISSR. Also, the present study aimed to examine the relationships among the accessions studied belonging to different genetic backgrounds. ResultsTen SSR and tan ISSR primers produced 2065 and 1524 polymorphism bands, respectively. The number of Polymorphic Bands (NPB), the Polymorphism Information Content (PIC), Marker Index (MI), and Resolving Power (Rp) in SSR marker was 162 to 317, 0.830 to 0.919, 1.326 to 3.167, and 3.169 to 5.692, respectively, and in the ISSR marker, it was from 103 to 185, 0.377 to 0.441, 0.660 to 1.151, and 3.169 to 5.693, respectively. This indicates the efficiency of both markers in detecting polymorphism among the accessions studied. The ISSR marker had a higher polymorphism rate, MI, and Rp than the SSR marker. Molecular analysis of variance for both DNA-based markers showed that the genetic variation within the species was more than the genetic diversity between them. The high level of genomic diversity discovered in the Aegilops and Triticum species proved to provide an ideal gene pool for discovering genes useful for wheat breeding. The accessions were classified into eight groups based on SSR and ISSR markers using the UPGMA method of cluster analysis. According to the cluster analysis results, despite similarities between the accessions of a given province, in most cases, the geographical pattern was not in accordance with that observed using the molecular clustering. Based on the coordinate analysis, neighboring groups showed the maximum similarities, and distant ones revealed the maximum genetic distance from each other. The genetic structure analysis successfully separated accessions for their ploidy levels. ConclusionsBoth markers provided a comprehensive model of genetic diversity between Iranian accessions of Aegilops and Triticum genera. Primers used in the present study were effective, informative, and genome-specific which could be used in genome explanatory experiments.

Effect of NAM-1 genes on the protein content in grain and productivity indices in common wheat lines with foreign genetic material introgressions in the conditions of Belarus.

Modern varieties of common wheat (Triticum aestivum L.) bred mainly for high productivity are often of low grain quality. The identification of NAM-1 alleles associated with high grain protein content in wheat relatives has enhanced the significance of distant hybridization for the nutritional value of T. aestivum L. grain. In this work we aimed to study the allelic polymorphism of the NAM-A1 and NAM-B1 genes in wheat introgression lines and their parental forms and evaluate the effects of various NAM-1 variants on the grain protein content and productivity traits in the field conditions of Belarus. We studied parental varieties of spring common wheat, the accessions of tetraploid and hexaploid species of the genus Triticum and 22 introgression lines obtained using them (2017-2021 vegetation periods). Full-length NAM-A1 nucleotide sequences of T. dicoccoides k-5199, T. dicoccum k-45926, T. kiharae, and T. spelta k-1731 accessions were established and registered with the international molecular database GenBank. Six combinations of NAM-A1/B1 alleles were identified in the accessions studied and their frequency of occurrence varied from 40 to 3 %. The cumulative contribution of NAM-A1 and NAM-B1 genes to the variability of economically important wheat traits ranged from 8-10 % (grain weight per plant and thousand kernel weight) to up to 72 % (grain protein content). For most of the traits studied, the proportion of variability determined by weather conditions was small (1.57-18.48 %). It was shown that, regardless of weather conditions, the presence of a functional NAM-B1 allele ensures a high level of grain protein content; at the same time, it does not significantly decrease thousand kernel weight. The genotypes combining the NAM- A1d haplotype and a functional NAM-B1 allele demonstrated high levels of productivity and grain protein content. The results obtained demonstrate the effective introgression of a functional NAM-В1 allele of related species increasing the nutritional value of common wheat.

Host Specificity of Soilborne Pathogens in Hordeum Species and Their Relatives.

Soilborne pathogens destabilize the yields of Triticeae crops, including barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.). Although genetic resistance derived from relatives of these species has been utilized to prevent rust diseases (i.e., in the wheat-rye 1BL-1RS translocation line), research on resistance against soilborne pathogens remains limited. Here, we performed field trials using 76 genotypes representing 28 Hordeum, six Triticum, and two Aegilops species to examine resistance against three soilborne bymoviruses: barley yellow mosaic virus (BaYMV), barley mild mosaic virus (BaMMV), and wheat yellow mosaic virus (WYMV). We also performed greenhouse tests using the soilborne fungal pathogen Fusarium pseudograminearum, which causes Fusarium crown rot (FCR). Using RT-PCR, we detected BaMMV and BaYMV in several Hordeum species, whereas WYMV induced systemic infection in the Triticum and Aegilops species. The identification of FCR susceptibility in all species examined suggests that F. pseudograminearum is a facultative fungal pathogen in Triticeae. Intraspecies variation in FCR disease severity was observed for several species, pointing to the possibility of exploring host resistance mechanisms. Therefore, by unlocking the host specificity of four soilborne pathogens in Hordeum species and their relatives, we obtained insights for the further exploration of wild sources of soilborne pathogen resistance for future wheat and barley improvement programs.

Elucidating the Genetic Relationships on the Original Old Sicilian Triticum Spp. Collection by SNP Genotyping.

Several Triticum species spread in cultivation in Sicily and neighboring regions over the centuries, which led to the establishment of a large genetic diversity. Many ancient varieties were widely cultivated until the beginning of the last century before being replaced by modern varieties. Recently, they have been reintroduced in cultivation in Sicily. Here, the genetic diversity of 115 and 11 accessions from Sicily and Calabria, respectively, belonging to Triticum species was evaluated using a high-density SNP array. Einkorn, emmer, and spelta wheat genotypes were used as outgroups for species and subspecies; five modern varieties of durum and bread wheat were used as references. A principal coordinates analysis (PCoA) and an unweighted pair group method with arithmetic mean (UPGMA) showed four distinct groups among Triticum species and T. turgidum subspecies. The population structure analysis distinguished five gene pools, among which three appeared private to the T. aestivum, T. turgidum subsp. Turgidum, and 'Timilia' group. The principal component analysis (PCA) displayed a bio-morphological trait relationship of a subset (110) of ancient wheat varieties and their wide variability within the T. turgidum subsp. durum subgroups. A discriminant analysis of principal components (DAPC) and phylogenetic analyses applied to the four durum wheat subgroups revealed that the improved varieties harbored a different gene pool compared to the most ancient varieties. The 'Russello' and 'Russello Ibleo' groups were distinguished; both displayed higher genetic variability compared to the 'Timilia' group accessions. This research represents a comprehensive approach to fingerprinting the old wheat Sicilian germplasm, which is useful in avoiding commercial fraud and sustaining the cultivation of landraces and ancient varieties.

Association Analysis for Some Biochemical Traits in Wild Relatives of Wheat under Drought Stress Conditions.

In the present study, we estimated genetic diversity and population structure in 186 accessions of Triticum and Aegilops species using 24 simple sequence repeat markers (SSR). Furthermore, an association analysis was performed for antioxidant activities, including guaiacol peroxidase (GPX), ascorbate peroxidase (APX), peroxidase (POX), catalase (CAT), and dry matter (DM) under two control and drought stress conditions. Our findings showed that drought treatment significantly decreased DM, whereas activities of all antioxidant enzymes were increased compared to the control conditions. The results of correlation analysis indicated that, under drought stress conditions, all biochemical traits had a positive and significant association with each other and with dry matter. In the molecular section, the results of the analysis of molecular variance (AMOVA) indicated that the molecular variation within species is more than within them. The dendrogram obtained by cluster analysis showed that grouping the investigated accessions was in accordance with their genomic constitutions. The results of association analysis revealed 8 and 9 significant marker–trait associations (MTA) under control and drought stress conditions, respectively. Among identified MTAs, two associations were simultaneously found in both growing conditions. Moreover, several SSR markers were associated with multiple traits across both conditions. In conclusion, our results could provide worthwhile information regarding marker-assisted selection for the activity of antioxidant enzymes in future breeding programs.

Wheat photosystem II heat tolerance responds dynamically to short- and long-term warming.

Wheat photosynthetic heat tolerance can be characterized using minimal chlorophyll fluorescence to quantify the critical temperature (Tcrit) above which incipient damage to the photosynthetic machinery occurs. We investigated intraspecies variation and plasticity of wheat Tcrit under elevated temperature in field and controlled-environment experiments, and assessed whether intraspecies variation mirrored interspecific patterns of global heat tolerance. In the field, wheat Tcrit varied diurnally-declining from noon through to sunrise-and increased with phenological development. Under controlled conditions, heat stress (36 °C) drove a rapid (within 2 h) rise in Tcrit that peaked after 3-4 d. The peak in Tcrit indicated an upper limit to PSII heat tolerance. A global dataset [comprising 183 Triticum and wild wheat (Aegilops) species] generated from the current study and a systematic literature review showed that wheat leaf Tcrit varied by up to 20 °C (roughly two-thirds of reported global plant interspecies variation). However, unlike global patterns of interspecies Tcrit variation that have been linked to latitude of genotype origin, intraspecific variation in wheat Tcrit was unrelated to that. Overall, the observed genotypic variation and plasticity of wheat Tcrit suggest that this trait could be useful in high-throughput phenotyping of wheat photosynthetic heat tolerance.

An Analysis of Genetic Variability and Population Structure in Wheat Germplasm Using Microsatellite and Gene-Based Markers.

Knowledge of the natural patterns of genetic variation and their evolutionary basis is required for sustainable management and conservation of wheat germplasm. In the current study, the genetic diversity and population structure of 100 individuals from four Triticum and Aegilops species (including T. aestivum, Ae. tauschii, Ae. cylindrica, and Ae. crassa) were investigated using two gene-based markers (start codon targeted (SCoT) polymorphism and CAAT-box derived polymorphism (CBDP)) and simple-sequence repeats (SSRs). The SCoT, CBDP, and SSR markers yielded 76, 116, and 48 polymorphism fragments, respectively. The CBDP marker had greater efficiency than the SCoT and SSR markers due to its higher polymorphism content information (PIC), resolving power (Rp), and marker index (MI). Based on an analysis of molecular variance (AMOVA) performed using all marker systems and combined data, there was a higher distribution of genetic variation within species than among them. Ae. cylindrica and Ae. tauschii had the highest values for all genetic variation parameters. A cluster analysis using each marker system and combined data showed that the SSR marker had greater efficiency in grouping of tested accessions, such that the results of principal coordinate analysis (PCoA) and population structure confirmed the obtained clustering patterns. Hence, combining the SCoT and CBDP markers with polymorphic SSR markers may be useful in genetic fingerprinting and fine mapping and for association analysis in wheat and its germplasm for various agronomic traits or tolerance mechanisms to environmental stresses.