Aegilops Biuncialis Research Articles

Chromosome genomics facilitates the marker development and selection of wheat-Aegilops biuncialis addition, substitution and translocation lines

The annual goatgrass, Aegilops biuncialis is a rich source of genes with considerable agronomic value. This genetic potential can be exploited for wheat improvement through interspecific hybridization to increase stress resistance, grain quality and adaptability. However, the low throughput of cytogenetic selection hampers the development of alien introgressions. Using the sequence of flow-sorted chromosomes of diploid progenitors, the present study enabled the development of chromosome-specific markers. In total, 482 PCR markers were validated on wheat (Mv9kr1) and Ae. biuncialis (MvGB642) crossing partners, and 126 on wheat-Aegilops additions. Thirty-two markers specific for U- or M-chromosomes were used in combination with GISH and FISH for the screening of 44 Mv9kr1 × Ae. biuncialis BC3F3 genotypes. The predominance of chromosomes 4M and 5M, as well as the presence of chromosomal aberrations, may indicate that these chromosomes have a gametocidal effect. A new wheat-Ae. biuncialis disomic 4U addition, 4M(4D) and 5M(5D) substitutions, as well as several introgression lines were selected. Spike morphology and fertility indicated that the Aegilops 4M or 5M compensated well for the loss of 4D and 5D, respectively. The new cytogenetic stocks represent valuable genetic resources for the introgression of key genes alleles into wheat.

Classification of 17 species Aegilops using DNA barcoding and SNPs, reveals gene flow among Aegilops biuncialis, Aegilops juvenalis, and Aegilops columnaris.

Rapid changes in agricultural environments caused by global warming pose a major challenge to food production and safety. Common wheat (Triticum aestivum) is a hexaploid plant (AABBDD) that shares large numbers of quantitative traits and resistance genes with B and D genomes of Aegilops species, which are responsible for several metabolic functions and biosynthetic processes, particularly in plant adaptation to biotic as well as abiotic stresses. Comparatively, the abundance of the Aegilops gene pool is much higher than that of Triticum. Therefore, we used four universal DNA barcodes for plants (ITS2, matK, rbcL, and psbM-petN) to construct a phylogenetic tree to classify the genus Aegilops. Fourteen species were distinguished among a total of 17 representative species. Aegilops biuncialis, Aegilops juvenalis, and Aegilops umbellulata could not be grouped into any of the clusters in the phylogenetic tree, indicating that these three species could not be distinguished by four DNA barcodes. Therefore, from 2408 SNPs obtained using genotyping by sequencing (GBS), we manually screened 30 SNPs that could be potentially used to classify these three species. The results of gene flow and genetic differentiation index (Fst) showed that the genetic differentiation among the three species was small, and there was bidirectional horizontal gene transfer between the three species, which was consistent with our results that the three species were difficult to classify by DNA barcode.

Mapping of the novel powdery mildew resistance gene Pm2Mb from Aegilops biuncialis based on ph1b-induced homoeologous recombination.

A novel powdery mildew resistance gene Pm2Mb from Aegilops biuncialis was transferred into common wheat and mapped to chromosome 2MbL bin FL 0.49-0.66 by molecular cytogenetic analysis of 2Mb recombinants. Aegilops biuncialis, a wild relative of common wheat, is highly resistant to powdery mildew. Previous studies identified that chromosome 2Mb in Chinese Spring (CS)-Ae. biuncialis 2Mb disomic addition line TA7733 conferred high resistance to powdery mildew, and the resistance gene was temporarily designated as Pm2Mb. In this study, a total of 65 CS-Ae. biuncialis 2Mb recombinants were developed by ph1b-induced homoeologous recombination and they were grouped into 12 different types based on the presence of different markers of 2Mb-specificity. Segment sizes and breakpoints of each 2Mb recombinant type were further characterized using in situ hybridization and molecular marker analyses. Powdery mildew responses of each type were assessed by inoculation of each 2Mb recombinant-derived F2 progenies using the isolate E05. Combined analyses of in situ hybridization, molecular markers and powdery mildew resistance data of the 2Mb recombinants, the gene Pm2Mb was cytologically located to an interval of FL 0.49-0.66 in the long arm of 2Mb, where 19 2Mb-specific markers were located. Among the 65 2Mb recombinants, T-11 (T2DS.2DL-2MbL) and T-12 (Ti2DS.2DL-2MbL-2DL) contained a small 2MbL segment harboring Pm2Mb. Besides, a physical map of chromosome 2Mb was constructed with 70 2Mb-specific markers in 10 chromosomal bins and the map showed that submetacentric chromosome 2Mb of Ae. biuncialis was rearranged by a terminal intrachromosomal translocation. The newly developed 2Mb recombinants with powdery mildew resistance, the 2Mb-specific molecular markers and the physical map of chromosome 2Mb will benefit wheat disease breeding as well as fine mapping and cloning of Pm2Mb.

Identification of New QTLs for Dietary Fiber Content in Aegilops biuncialis.

Grain dietary fiber content is an important health-promoting trait of bread wheat. A dominant dietary fiber component of wheat is the cell wall polysaccharide arabinoxylan and the goatgrass Aegilops biuncialis has high β-glucan content, which makes it an attractive gene source to develop wheat lines with modified fiber composition. In order to support introgression breeding, this work examined genetic variability in grain β-glucan, pentosan, and protein content in a collection of Ae. biuncialis. A large variation in grain protein and edible fiber content was revealed, reflecting the origin of Ae. biuncialis accessions from different eco-geographical habitats. Association analysis using DArTseq-derived SNPs identified 34 QTLs associated with β-glucan, pentosan, water-extractable pentosan, and protein content. Mapping the markers to draft chromosome assemblies of diploid progenitors of Ae. biuncialis underlined the role of genes on chromosomes 1Mb, 4Mb, and 5Mb in the formation of grain β-glucan content, while other QTLs on chromosome groups 3, 6, and 1 identified genes responsible for total- and water-extractable pentosan content. Functional annotation of the associated marker sequences identified fourteen genes, nine of which were identified in other monocots. The QTLs and genes identified in the present work are attractive targets for chromosome-mediated gene transfer to improve the health-promoting properties of wheat-derived foods.

Variability in Physiological Traits Reveals Boron Toxicity Tolerance in Aegilops Species.

Boron (B) is an important micronutrient required for the normal growth and development of plants. However, its excess in the soil causes severe damage to plant tissues, which affects the final yield. Wheat, one of the main staple crops, has been reported to be largely affected by B toxicity stress in arid and semi-arid regions of the world. The prevalence of B toxicity stress can be addressed by utilizing wild wheat genotypes with a variant level of stress tolerance. Wild wheat relatives have been identified as a prominent source of several abiotic stress-tolerant genes. However, Aegilops species in the tertiary gene pool of wheat have not been well exploited as a source of B toxicity tolerance. This study explores the root and shoot growth, proline induction, and extent of lipid peroxidation in 19 Aegilops accessions comprising 6 different species and the B-tolerant check wheat cultivar Bolal 2973 grown under Control (3.1 μM B), toxic (1 mM B), and highly toxic (10 mM B) B stress treatment. B toxicity stress had a more decisive impact on growth parameters as compared to the malondialdehyde (MDA) and proline content. The obtained results suggested that even the genotypes with high shoot B (SB) accumulation can be tolerant to B toxicity stress, and the mechanism of B redistribution in leaves should be studied in detail. It has been proposed that the studied Aegilops accessions can be potentially used for genetically improving the B toxicity-tolerance trait due to a high level of variation in the response toward high B toxicity. Though a number of accessions showed suppression in the root and shoot growth, very few accessions with stress adaptive plasticity to B toxicity stress leading to an improvement of shoot growth parameters could be determined. The two accessions, Aegilops biuncialis accession TGB 026219 and Aegilops columnaris accession TGB 000107, were identified as the potential genotypes with B toxicity stress tolerance and can be utilized for developing a pre-breeding material in B tolerance-based breeding programs.

Grain quality indices in common wheat lines with introgressions of chromosome 1U from Aegilops biuncialis Vis.

Aim. The aim of this study was to analyze grain quality indices in winter common wheat lines with introgressions of chromosome 1U from Aegilops biuncialis Vis. marked by storage protein loci. Methods. Acid polyacrylamide gel electrophoresis and SDS-electrophoresis of storage proteins were performed to identify introgressions. Grain quality indices (SDS sedimentation volume and grain protein content) were analyzed in lines with introgressed chromosome 1U or its arm 1UL, as well as in the cultivars Panna and Bezostaya 1. Results. SDS-sedimentation volume in the cultivars and lines depended on year’s conditions. The studying of the lines during two years has demonstrated that the presence of the allele at the high molecular weight glutenin subunit locus Glu-U1 from Ae. biuncialis was associated with a high volume of SDS-sedimentation SDS30 (higher than that in the cultivar Bezostaya 1). The introgressive lines show high grain protein content. Conclusions. The effect of the allele at the high molecular weight glutenin subunit locus Glu-U1 from Ae. biuncialis on SDS-sedimentation value is similar to that of the high-quality allele Glu-B1al. The lines with the introgressed allele at Glu-U1 from Ae. biuncialis are valuable initial material for breeding for quality.Keywords: Triticum aestivum, Aegilops biuncialis, high molecular weight glutenin subunits, SDS-sedimentation, protein content.

Crop Wild Relatives (CWR) Priority in Italy: Distribution, Ecology, In Situ and Ex Situ Conservation and Expected Actions

The study presents an updated overview of the 14 non-endemic threatened crop wild relatives (CWR) in Italy: Aegilops biuncialis, Ae. uniaristata, Ae. ventricosa, Asparagus pastorianus, Beta macrocarpa, Brassica insularis, B. montana, Crambe hispanica subsp. hispanica, C. tataria subsp. tataria, Ipomoea sagittata, Lathyrus amphicarpos, L. palustris, Vicia cusnae and V. serinica. Geographical distribution, ecology (with plant communities and habitat 92/43/EEC aspects), genetics (focused on gene pools), property, and in situ and ex situ conservation were analyzed. In addition, with the aim of their protection and valorization, specific actions are recommended.

An overview of innovative developments from the scientific provision of plant selection to resistance to diseases and pests

The Institute of Plant Protection of NAAS developed methods of plant selection for resistance to major pathogens and assessment methodology the resistance of winter wheat, potatoes, clover and alfalfa to pests to create complex resistant varieties. Donors of potato resistance to cancer, Alternaria, Phomosis and cyst-forming nematodes were identified. Methods for determining the resistance of cereals to high and low temperatures were developed. A collection of the Aegilops biuncialis L. wild wheat samples as sources of new resistance genes to plant diseases and pests was compiled. The soft winter wheat resistance genes to diseases by DNA markers were identified at the Institute of Plant Production named after V. Ya. Yuriev. The V. M. Remeslo Myronivka Institute of Wheat formed a set of winter wheat cultivars with group and complex resistance to diseases and pests. The Institute of Oilseed Crops of NAAS established physiological and biochemical mechanisms of resistance of sunflower, soybean, crown flax to pathogens. Collections of sunflower lines based on complex resistance to sunflower broomrape, dry rot, downy mildew and soybean lines based on complex resistance to white rot and Anthracnose were also created. In the National Scientific Center "Institute of Agriculture of NAAS", the fodder lupine resistance to the most important pathogens was investi-gated. The Institute of Agriculture in the Carpathian Region of NAAS revealed the spring barley, oat, rape, fiber flax varieties and selection numbers resistant to basic diseases; and the Institute of Rice of NAAS – rice cultivars resistant to diseases and pest pathogens. The resistance to main phytophagous insects of the modern genotypes of hemp, fiber flax and crown flax was assessed by the Institute of Agriculture of the North-East of NAAS. The assessment method of breeding value for the initial material of the main vegetables on the basis of disease resistance was developed by the Institute of Vegetables and Melons Growing of NAAS. Scientists of the Institute of Agroecology and Environmental Management of NAAS and V. M. RemesloMyronivka Institute of Wheat of NAAS revealed the cucumber and barley resistance to viral diseases. Key words: crops, pests, pathogens, resistance, resistance gene, resistance source.

Innovations on scientific support of grain crop breeding for resistance to diseases and pests

Goal. Database formation of innovations in the scientific provision of breeding crops for resistance to pathogens and pests — grounds for creating sustainable varieties.
 Methods. Analysis of innovative development of the Institute of Plant Protection of the National Academy of Agrarian Sciences of Ukraine and other institutions of the Scientific and Methodological Center «Protection of Plants» for 2001—2020. Isolation of those relating to the problem of grain crops’ resistance to pests and pathogens.
 Results. Methods of selection of wheat and barley for resistance to basic pathogens of diseases and methodology for assessing the stability of winter wheat stability to pests to create complex resistant varieties are developed. A database for the resistance of corn hybrids against main pests was created. Methods of determining the stability of grain crops to high and low temperatures are developed. A collection of samples of wild relative of wheat Aegilops biuncialis L. that are sources of new genes for plant resistance to diseases and pests was created. Genes of resistance of soft winter wheat to diseases by DNA markers have been identified. A set of varieties of winter wheat with group and complex resistance to diseases and pests has been formed. Physiological and biochemical mechanisms of soybean resistance to pathogens of diseases are established. Collection of soybean lines is created on the basis of complex resistance to white rot and anthracnosis. The varieties and selection numbers of spring barley, oats, resistant to basic diseases, as well as rice varieties that are resistant to pathogens of diseases and pests were identified. Resistance to viral diseases has been found in barley plants.
 Conclusions. The established innovations can be widely used by breeding centers and other scientific institutions of the agrarian profile when of output sustainable grain and leguminous grain crops. In this case, the timing of the selection process can be accelerated by 40—60%.

Addition of Aegilops biuncialis chromosomes 2M or 3M improves the salt tolerance of wheat in different way

Aegilops biuncialis is a promising gene source to improve salt tolerance of wheat via interspecific hybridization. In the present work, the salt stress responses of wheat-Ae. biuncialis addition lines were investigated during germination and in young plants to identify which Aegilops chromosomes can improve the salt tolerance of wheat. After salt treatments, the Aegilops parent and the addition lines 2M, 3M and 3M.4BS showed higher germination potential, shoot and root growth, better CO2 assimilation capacity and less chlorophyll degradation than the wheat parent. The Aegilops parent accumulated less Na in the roots due to an up-regulation of SOS1, SOS2 and HVP1 genes, while it contained higher amount of proline, fructose, glucose, galactose, maltose and raffinose. In the leaves, lower Na level was accompanied by high amount of proline and increased expression of NHX2 gene. The enhanced accumulation of sugars and proline was also observed in the roots of 3M and 3M.4BS addition lines. Typical mechanism of 2M addition line was the sequestration of Na into the vacuole due to the increased expression of HVP1 in the roots and NHX2 in the leaves. These results suggest the Aegilops chromosomes 2M and 3M can improve salt tolerance of wheat in different way.

Special features of transmission of markers for Aegilops biuncialis Vis. Chromosome 1U in common wheat hybrids

Aim. The wild wheat relative Aegilops biuncialis Vis. is a potential source of new storage protein alleles for enriching the common wheat gene pool. We have produced the wheat material from direct crossing of common wheat with Crimean samples of Ae. biuncialis followed by backcrossing with wheat. Using storage proteins as genetic markers, lines with introgressions of chromosome 1U have been selected. The objective of the investigation was to study the transmission of markers for chromosome 1U in the hybrid from crossing the common wheat cultivar Bezostaya 1 with a line carrying chromosome 1U. Methods. F2 seeds from the cross of the common wheat cultivar Besostaya 1 and the line NVG41 carrying Ae. biuncialis chromosome 1U were analyzed. Storage proteins encoded by Gli-U1 and Glu-U1 served as markers for chromosome 1U. Gliadins were analyzed by acid polyacrylamide gel electrophoresis by the procedure of Kozub et al. (2009). Electrophoresis of total seed proteins, including high-molecular-weight glutenin subunits, was carried out by the procedure of Laemmli (1970).Results. Among the F2 seeds analyzed, we identified four classes of genotypes with respect to the markers Gli-U1 and Glu-U1: 1) with complete chromosome 1U, 2) with the 1UL arm only, 3) with the 1US arm only, 4) without chromosome 1U. In the F1 hybrid NVG41 × Bezostaya 1, Ae. biuncialis chromosome 1U was transmitted with an increased frequency (with respect to the marker Glu-U1 and the simultaneous presence of the markers Gli-U1 and Glu-U1). The frequency of centric misdivision of chromosome 1U (univalent) in the F1 hybrid amounted about 9 %. This resulted in a significantly lower number of seeds with the 1US arm only (2 %) than that with the 1UL arm (6 %).Conclusions. In the progeny of F1 hybrids with Ae. biuncialis univalent 1U, a lower frequency of genotypes with the 1US arm only as compared with the 1UL arm only can be observed at the grain stage. This could be due to the loss of telocentrics with the 1US arm at gamete formation or reduced viability of genotypes with 1US only at the gamete stage or after zygote formation.Manuscript received 02.04.2020

Unlocking the Genetic Diversity and Population Structure of a Wild Gene Source of Wheat, Aegilops biuncialis Vis., and Its Relationship With the Heading Time.

Understanding the genetic diversity of Aegilops biuncialis, a valuable source of agronomical useful genes, may significantly facilitate the introgression breeding of wheat. The genetic diversity and population structure of 86 Ae. biuncialis genotypes were investigated by 32700 DArT markers with the simultaneous application of three statistical methods— neighbor-joining clustering, Principal Coordinate Analysis, and the Bayesian approach to classification. The collection of Ae. biuncialis accessions was divided into five groups that correlated well with their eco-geographic habitat: A (North Africa), B (mainly from Balkans), C (Kosovo and Near East), D (Turkey, Crimea, and Peloponnese), and E (Azerbaijan and the Levant region). The diversity between the Ae. biuncialis accessions for a phenological trait (heading time), which is of decisive importance in the adaptation of plants to different eco-geographical environments, was studied over 3 years. A comparison of the intraspecific variation in the heading time trait by means of analysis of variance and principal component analysis revealed four phenotypic categories showing association with the genetic structure and geographic distribution, except for minor differences. The detailed exploration of genetic and phenologic divergence provides an insight into the adaptation capacity of Ae. biuncialis, identifying promising genotypes that could be utilized for wheat improvement.

Discovery of powdery mildew resistance gene candidates from Aegilops biuncialis chromosome 2Mb based on transcriptome sequencing.

Powdery mildew is one of the most widespread diseases of wheat. The development and deployment of resistant varieties are one of the most economical and effective methods to manage this disease. Our previous study showed that the gene(s) at 2Mb in Chinese Spring (CS)-Aegilops biuncialis 2Mb disomic addition line TA7733 conferred a high level of resistance to powdery mildew of wheat. In this study, resistance spectrum of TA7733 was assayed by using 15 Blumeria graminis f. sp. tritici (Bgt) isolates prevalent in different regions of China. The result indicated that TA7733 was highly resistant to all tested Bgt isolates and the gene(s) on chromosome 2Mb conferred broad-spectrum resistance to powdery mildew. In order to characterize mechanism of powdery mildew resistance by identifying candidates R-genes derived from Ae. biuncialis chromosome 2Mb and develop 2Mb-specific molecular markers, we performed RNA-seq analysis on TA7733 and CS. In total we identified 7,278 unigenes that showed specific expression in TA7733 pre and post Bgt-infection when compared to CS. Of these 7,278 unigenes, 295 were annotated as putative resistance (R) genes. Comparatively analysis of R-gene sequences from TA7733 and CS and integration CS Ref Seq v1.0 were used to develop R-gene specific primers. Of 295 R-genes we identified 53 R-genes were specific to 2Mb and could be involved in powdery mildew resistance. Functional annotation of majority of the 53 R-genes encoded nucleotide binding leucine rich repeat (NLR) protein. The broad-spectrum resistance to powdery mildew in TA7733 and availability of 2Mb-derived putative candidate R-gene specific molecular markers identified in this study will lay foundations for transferring powdery mildew resistance from 2Mb to common wheat by inducing CS-Ae. biuncialis homoeologous recombination. Our study also provides useful candidates for further isolation and cloning of powdery mildew resistance gene(s) from Ae. biuncialis chromosome 2Mb.

Studying common wheat material from crosses with Aegilops biuncialis vis. using markers for chromosome 1U

Aim. The aim of the research was to study common wheat material developed from crosses with Aegilops biuncialis Vis. using storage protein loci as markers for chromosome 1U. Methods. SDS and APAG electrophoreses of seed storage proteins were employed to identify alleles at the Glu-1 and Gli-1 loci. The following markers of chromosome 1U of Ae. biuncialis were used: the Glu-U1 locus encoding high-molecular-weight glutenin subunits located on the long arm (1UL) and the gliadin locus Gli-U1 on the short arm (1US). Results. In F6–F7, elimination of chromosome 1U material with a frequency of about 0.222 proceeded. This indicates selection against unbalanced genotypes, which could be tracked using markers for chromosome 1U. In wheat F4–F6 hybrids from crosses with Ae. biuncialis, we revealed a high frequency of formation of genotypes possessing the 1UL arm and lacking 1US. Conclusions. Since the Glu-U1 locus on the arm 1UL encodes high-molecular-weight subunits which directly determine bread-making quality, the developed wheat material is a source of a new allele of this locus introgressed from Ae. biuncialis for enriching the common wheat gene pool. Keywords: Triticum aestivum, Aegilops biuncialis, storage proteins, introgression.

Development and studying of Triticum aestivum L. material with introgressions from Aegilops biuncialis Vis.

Aim. The aim of the study was to develop and study T. aestivum material with introgressions from Ae. biuncialis. Methods. Quantitative traits of F4 lines from crossing wheat with Crimean accessions of Ae. biuncialis were studied. SDS and APAG electrophoreses of storage proteins were used to identify alleles at the Glu-1 and Gli-1 loci, including introgressed ones. Results. F4 lines from crosses of wheat with Ae. biuncialis showed a wide range of yield traits. Some lines had a clavate spike and a hairy leaf blade. Using storage proteins as genetic markers the presence of chromosome 1U was identified among the progeny of plants analyzed; some of them had translocation of arm 1UL. Lines with introgressions of chromosome 1M were not revealed. Conclusions. T. aestivum lines with introgressions from Ae. biuncialis were developed without amphidiploid production. Lines with chromosome 1U were selected, including lines with translocations of arm 1UL.
 Keywords: Triticum aestivum L., Aegilops biuncialis Vis., introgression.

Intron length polymorphism of β-tubulin genes of Aegilops biuncialis Vis.

Intron-specific DNA polymorphism is present among plant β-tubulin gene family members and is considered to be one of the molecular markers based on the difference of tubulin introns length assayed both separately (TBP: 1st intron) or in combination (h-TBP: 1st and 2nd introns). These two approaches are possibly useful for wheat breeding programs, since TBP and h-TBP help to differentiate between the accessions of Aegilops biuncialis Vis., a wild relative of wheat. PCR-derived polymorphic fragments were resolved by PAGE electrophoresis. The length of amplicons varied significantly (395-3900 bp for TBP and 466-3440 bp for h-TBP), while the numbers of polymorphic bands were 21 for TBP and 23 for h-TBP, respectively. PIC mean value was circa 0.3. Dendrograms constructed on the basis of the Nei and Li coefficient with the high bootstrap support reveal a similar order of hierarchy for the samples analyzed using both methods. Thus, both techniques uncover DNA polymorphism level sufficiently high to distinguish different accessions of Ae. biuncialis Vis.

Adaptation of the Pivotal-Differential Genome Pattern for the Induction of Intergenomic Chromosome Recombination in Hybrids of Synthetic Amphidiploids within Triticeae Tribe.

A pivotal-differential evolution pattern is when two allopolyploids share a common genome, which is called pivotal, and differ with respect to the other genome or genomes, called differential. This feature induces the intergenomic recombination between chromosomes of differential genomes, which can lead to speciation. Our study is a cytomolecular insight into this mechanism which was adapted for the induction of intergenomic chromosome recombination in hybrids of synthetic amphidiploids Aegilops biuncialis × S. cereale (UUMMRR) and triticale (AABBRR) where R-genome was pivotal. We observed chromosome recombination events which were induced by both: (1) random chromosome fragmentation and non-homologous chromosome end joining at mitosis of root meristem cells and (2) intergenomic chromosome associations at meiosis of pollen mother cells (PMCs) of F1 hybrids. Reciprocal chromosome translocations were identified in six F1 plants and 15 plants of F2 generation using fluorescence in situ hybridization (FISH) with DNA clones (pTa-86, pTa-k374, pTa-465, pTa-535, pTa-k566, and pTa-713). We observed signals of pTa-86, pTa-535, and pTa-k566 probes in several chromosome breakpoints. The comparison of the DNA clone sequences distinguished a number of common motifs, which can be considered as characteristics of chromosome breakpoint loci. Immunodetection of synaptonemal complex proteins and genomic in situ hybridization analysis at meiosis of PMCs of F1 hybrids showed, that the homologous pairing of pivotal R—genome chromosomes is crucial for the fertility of F1 hybrids, however, these chromosomes can be also involved in the intergeneric recombination.

Characterization of a New Wheat-Aegilops biuncialis1Mb(1B) Substitution Line with Good Quality-associated HMW Glutenin Subunit

In this study, a new substitution line, 12-5-1, with 42 chromosomes that was derived from BC3F2 descendants of the hybridization between Triticum aestivum cv. CN19 and Aegilops biuncialis was created and reported. The 12-5-1 was immune to both powdery mildew and stripe rust and has stable fertility. Multi-color fluorescence in situ hybridization indicated that 12-5-1 was a substitution line 1Mb(1B). The seed storage protein electrophoresis showed that 12-5-1 presented high molecular weight glutenin subunits (2 + 12) of CN19 and a new subunit designated as M which apparently originated from parent Ae. biuncialis, and absent 7 + 8 subunits. Additionally, the flour quality parameters showed that the protein content, Zeleny sedimentation value, wet gluten content, and grain hardness and mixing time of 12-5-1 were signifiantly higher than those of its parent CN19. Moreover, 5 pairs of the chromosome 1Mb-specifi polymerase chain reaction-based landmark unique gene markers, TNAC1021, TNAC1026, TNAC1041, TNAC1-02...

Germination requirements of nine European Aegilops species in relation to constant and alternating temperatures

The genus Aegilops represents the secondary gene pool of wheat. A better understanding of the germination behaviour of Aegilops species is important to improve their use in breeding programmes and strengthen their in situ/ex situ conservation. In this study, we investigated the germination behaviour of nine Aegilops species, five of them not yet investigated, under two alternating and two constant temperatures. Seed germination was higher than 60% in all temperature treatments and species. Alternating temperatures promoted higher germination rates in all the species and significantly enhanced seed germination in three species (Aegilops biuncialis, Aegilops geniculata and Aegilops neglecta), in comparison with constant temperatures. One of the rarest and least productive species in the genus (Aegilops uniaristata) displayed the highest germination. This study suggests that different (seed) regeneration strategies/niches occur across Aegilops species.

Biotechnological characterization of a diverse set of wheat progenitors (Aegilops sp. and Triticum sp.) using callus culture parameters

It is known that genetic diversity is the most important factor in classical and modern plant breeding. The considerable increase in the number of transgenic crops reveals the value of new plant genetic resources. In this study, a set of 12 wheat progenitors were screened for tissue culture parameters such as callus induction, callus weight, regeneration capacity of callus and callus efficiency using mature embryos. Embryos were excised from imbibed seeds of the progenitors. The excised embryos were placed scutellum upwards in dishes containing 2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction. The developed calli and regenerated plants were maintained on 2,4-D free MS medium. When mature embryos of 12 wheat progenitors (Aegilops sp. and Triticum sp.) were compared, significant differences were detected in callus induction frequency, weight of callus, regeneration capacity and culture efficiency. A significant genotypic effect was observed on the culture responses. Of the 12 wheat progenitors tested, Aegilops umbellulata had the highest regeneration capacity of callus. Aegilops biuncialis created the most regenerable calli because of the highest callus induction and culture efficiency. In the experiment, callus induction was significantly correlated with callus weight (r= 0.820) and regeneration capacity (r= 0.955). Weight of callus was significantly correlated with regeneration capacity (r= 0.740), while there was no significant correlation between callus induction frequency and culture efficiency (r= 0.350). Our results showed that, generally, mature embryos of some Aegilops and Triticum species have a high regeneration capacity, and therefore, can be used as an effective explant source for the successful application of biotechnology in crop improvement.