ABSTRACT
BACKGROUND: As an important forage in arid and semi-arid regions, Agropyron cristatum provides livestock with exceptionally high nutritional value. Additionally, A. cristatum exhibits outstanding genetic characteristics to endure drought and disease. Therefore, rich genetic diversity serves as a cornerstone for the improvement of major food crops. The purposes of this study were to systematically describe mitogenome of A.cristatum and preliminarily analyze its internal variations. RESULT: The A. cristatum mitogenome was a single-ring molecular structure of 381,065 bp that comprised 52 genes, including 35 protein-coding, 3 rRNA and 14 tRNA genes. Among these, two pseudoprotein-coding genes and multiple copies of tRNA genes were observed. A total of 320 repetitive sequences was found to cover more than 10% of the mitogenome (105 simple sequences, 185 dispersed and 30 tandem repeats), which led to a large number of fragment rearrangements in the mitogenome of A. cristatum. Leucine was the most frequent amino acid (n = 1087,10.8%) in the protein-coding genes of A. cristatum mitogenome, and the highest usage codon was ATG (initiation codon). The number of A/T changes at the third base of the codon was much higher than that of G/C. Among 23 PCGs, the range of Pi values is from 0.0021 to 0.0539, with an average of 0.013. Additionally, 81 RNA editing sites were predicted, which were considerably fewer than those reported in other plant mitogenomes. Most of the RNA editing site base positions were concentrated at the first and second codon bases, which were C to T transitions. Moreover, we identified 95 sequence fragments (total length of 34, 343 bp) that were transferred from the chloroplast to mitochondria genes, introns, and intergenic regions. The stability of the tRNA genes was maintained during this process. Selection pressure analysis of 23 protein-coding genes shared by 15 Poaceae plants, showed that most genes were subjected to purifying selection during evolution, whereas rps4, cob, mttB, and ccmB underwent positive selection in different plants. Finally, a phylogenetic tree was constructed based on 22 plant mitogenomes, which showed that Agropyron plants have a high degree of independent heritability in Triticeae. CONCLUSION: The findings of this study provide new data for a better understanding of A. cristatum genes, and demonstrate that mitogenomes are suitable for the study of plant classifications, such as those of Agropyron. Moreover, it provides a reference for further exploration of the phylogenetic relationships within Agropyron species, and establishes a theoretical basis for the subsequent development and utilization of A. cristatum plant germplasm resources.
Subject(s)
Agropyron , Genome, Mitochondrial , RNA Editing , Agropyron/genetics , RNA, Transfer/genetics , Phylogeny , Genome, PlantABSTRACT
To investigate the effects of discharge plasma on Agropyron mongolicum seeds, various treatments including direct exposure to discharge plasma, combined treatment with discharge plasma and plasma-activated water (PAW) were applied to the seeds. The changes in germination rate, MDA content, and volatile compound levels of Agropyron mongolicum seeds after different treatments were examined. The results showed that the direct effect of plasma had no significant effect on the MDA content or germination rate of Agropyron mongolicum seeds due to the limited penetration depth. However, the combined effect of plasma and activated water could cause active nitrogen and oxygen particles to enter the seeds and cause oxidative stress damage. After 18 h of combined treatment, the MDA content increased significantly, and the germination rate decreased to below the semilethal dose, which was 33.44 %. After plasma treatment, 55 volatile compounds, mainly alcohols, aldehydes and ketones, were identified from the seeds of Agropyron mongolicum. Due to the oxidation and modification of the plasma, the content of most aldehydes increased with increasing reaction time. After screening, 13 volatile organic compounds could be used as potential markers to distinguish between different treatment methods. These results reveal the mechanism underlying the biological effects of plasma treatment on Agropyron mongolicum seeds.
Subject(s)
Agropyron , Germination , Plasma Gases , Seeds , Volatile Organic Compounds , Seeds/growth & development , Seeds/metabolism , Seeds/chemistry , Volatile Organic Compounds/metabolism , Plasma Gases/pharmacology , Agropyron/metabolism , Oxidative Stress/drug effects , Malondialdehyde/metabolism , Malondialdehyde/blood , Aldehydes/metabolismABSTRACT
KEY MESSAGE: A grain weight locus from Agropyron cristatum chromosome 5P increases grain weight in different wheat backgrounds and is localized to 5PL (bin 7-12). Thousand-grain weight is an important trait in wheat breeding, with a narrow genetic basis being the main factor limiting improvement. Agropyron cristatum, a wild relative of wheat, harbors many desirable genes for wheat improvement. Here, we found that the introduction of the 5P chromosome from A. cristatum into wheat significantly increased the thousand-grain weight by 2.55-7.10 g, and grain length was the main contributor to grain weight. An increase in grain weight was demonstrated in two commercial wheat varieties, indicating that the grain weight locus was not affected by the wheat background. To identify the chromosome segment harboring the grain weight locus, three A. cristatum 5P deletion lines, two wheat-A. cristatum 5P translocation lines and genetic populations of these lines were used to evaluate agronomic traits. We found that the translocation lines harboring the long arm of A. cristatum chromosome 5P (5PL) exhibited high grain weight and grain length, and the genetic locus associated with increased grain weight was mapped to 5PL (bin 7-12). An increase in grain weight did not adversely affect other agronomic traits in translocation line 5PT2, which is a valuable germplasm resource. Overall, we identified a grain weight locus from chromosome 5PL and provided valuable germplasm for improving wheat grain weight.
Subject(s)
Agropyron , Chromosome Mapping , Chromosomes, Plant , Edible Grain , Phenotype , Plant Breeding , Quantitative Trait Loci , Triticum , Triticum/genetics , Triticum/growth & development , Agropyron/genetics , Agropyron/growth & development , Chromosomes, Plant/genetics , Edible Grain/genetics , Edible Grain/growth & development , Seeds/growth & development , Seeds/genetics , Genetic Introgression , Translocation, GeneticABSTRACT
KEY MESSAGE: We developed T1AL·1PS and T1AS·1PL Robertsonian translocations by breakage-fusion mechanism based on wheat-A. cristatum 1P(1A) substitution line with smaller leaf area, shorter plant height, and other excellent agronomic traits Agropyron cristatum, a wild relative of wheat, is a valuable germplasm resource for improving wheat genetic diversity and yield. Our previous study confirmed that the A. cristatum chromosome 1P carries alien genes that reduce plant height and leaf size in wheat. Here, we developed T1AL·1PS and T1AS·1PL Robertsonian translocations (RobTs) by breakage-fusion mechanism based on wheat-A. cristatum 1P (1A) substitution line II-3-1c. Combining molecular markers and cytological analysis, we identified 16 spontaneous RobTs from 911 F2 individuals derived from the cross of Jimai22 and II-3-1c. Fluorescence in situ hybridization (FISH) was applied to detect the fusion structures of the centromeres in wheat and A. cristatum chromosomes. Resequencing results indicated that the chromosomal junction point was located at the physical position of Triticum aestivum chromosome 1A (212.5 Mb) and A. cristatum chromosome 1P (230 Mb). Genomic in situ hybridization (GISH) in pollen mother cells showed that the produced translocation lines could form stable ring bivalent. Introducing chromosome 1PS translocation fragment into wheat significantly increased the number of fertile tillers, grain number per spike, and grain weight and reduced the flag leaf area. However, introducing chromosome 1PL translocation fragment into wheat significantly reduced flag leaf area and plant height with a negative effect on yield components. The pre-breeding of two spontaneous RobTs T1AL·1PS and T1AS·1PL was important for wheat architecture improvement.
Subject(s)
Agropyron , Chromosomes, Plant , Plant Breeding , Translocation, Genetic , Triticum , Triticum/genetics , Triticum/growth & development , Triticum/anatomy & histology , Agropyron/genetics , Agropyron/growth & development , Chromosomes, Plant/genetics , In Situ Hybridization, Fluorescence , PhenotypeABSTRACT
BACKGROUND: Agropyron cristatum (L.) is a valuable genetic resource for expanding the genetic diversity of common wheat. Pubing3228, a novel wheat-A. cristatum hybrid germplasm, exhibits several desirable agricultural traits, including high grain number per spike (GNS). Understanding the genetic architecture of GNS in Pubing3228 is crucial for enhancing wheat yield. This study aims to analyze the specific genetic regions and alleles associated with high GNS in Pubing3228. METHODS: The study employed a recombination inbred line (RIL) population derived from a cross between Pubing3228 and Jing4839 to investigate the genetic regions and alleles linked to high GNS. Quantitative Trait Loci (QTL) analysis and candidate gene investigation were utilized to explore these traits. RESULTS: A total of 40 QTLs associated with GNS were identified across 16 chromosomes, accounting for 4.25-17.17% of the total phenotypic variation. Five QTLs (QGns.wa-1D, QGns.wa-5 A, QGns.wa-7Da.1, QGns.wa-7Da.2 and QGns.wa-7Da.3) accounter for over 10% of the phenotypic variation in at least two environments. Furthermore, 94.67% of the GNS QTL with positive effects originated from Pubing3228. Candidate gene analysis of stable QTLs identified 11 candidate genes for GNS, including a senescence-associated protein gene (TraesCS7D01G148000) linked to the most significant SNP (AX-108,748,734) on chromosome 7D, potentially involved in reallocating nutrients from senescing tissues to developing seeds. CONCLUSION: This study provides new insights into the genetic mechanisms underlying high GNS in Pubing3228, offering valuable resources for marker-assisted selection in wheat breeding to enhance yield.
Subject(s)
Agropyron , Quantitative Trait Loci , Quantitative Trait Loci/genetics , Chromosome Mapping , Agropyron/genetics , Plant Breeding , Genetic Linkage , Triticum/genetics , Phenotype , Edible Grain/geneticsABSTRACT
KEY MESSAGE: A novel locus on Agropyron cristatum chromosome 6P that increases grain number and spikelet number was identified in wheat-A. cristatum derivatives and across 3 years. Agropyron cristatum (2n = 4x = 28, PPPP), which has the characteristics of high yield with multiple flowers and spikelets, is a promising gene donor for wheat high-yield improvement. Identifying the genetic loci and genes that regulate yield could elucidate the genetic variations in yield-related traits and provide novel gene sources and insights for high-yield wheat breeding. In this study, cytological analysis and molecular marker analysis revealed that del10a and del31a were wheat-A. cristatum chromosome 6P deletion lines. Notably, del10a carried a segment of the full 6PS and 6PL bin (1-13), while del31a carried a segment of the full 6PS and 6PL bin (1-8). The agronomic characterization and genetic population analysis confirmed that the 6PL bin (9-13) brought about an increase in grain number per spike (average increase of 10.43 grains) and spikelet number per spike (average increase of 3.67) over the three growing seasons. Furthermore, through resequencing, a multiple grain number locus was mapped to the physical interval of 593.03-713.89 Mb on chromosome 6P of A. cristatum Z559. The RNA-seq analysis revealed the expression of 537 genes in the del10a young spike tissue, with the annotation indicating that 16 of these genes were associated with grain number and spikelet number. Finally, a total of ten A. cristatum-specific molecular markers were developed for this interval. In summary, this study presents novel genetic material that is useful for high-yield wheat breeding initiatives to meet the challenge of global food security through enhanced agricultural production.
Subject(s)
Agropyron , Agropyron/genetics , Plant Breeding , Chromosomes, Plant/genetics , Triticum/genetics , Edible Grain/genetics , Genetic LociABSTRACT
Recently it has been recognized that herbal plants contain endogenous molecules with biostimulant properties, capable of inducing morphological and biochemical changes in crop plants. Therefore, the present experiment was conducted to screen herbal samples for their plant growth promoting properties. Twenty-five herbal extracts were tested for their biostimulating activity on wheat crop (Triticum aestivum) through seed priming. Morphological parameters chosen for evaluation include: percent seed germination, length and weight of seedling, wheat grass length and biomass. Biochemical parameters include: total phenolic and flavonoid, enzymatic activity of catalase and phenylalanine ammonium lyase and antioxidant activity. Results indicated an increase in the tested parameters by the extracts, however the biostimulant property varied between the selected herbal samples. Some of the samples, such as Phyllanthus emblica, Plumbago zeylanica, Catharanthus roseus and Baccopa monnieri, were highly effective in inducing plant growth promoting parameters. Principal component analysis was performed and herbal samples were grouped into categories based on their activity.
Subject(s)
Agropyron , Germination , Plant Development , Seedlings , BiomassABSTRACT
BACKGROUND: Grain number per spike (GNS) is a pivotal determinant of grain yield in wheat. Pubing 3228 (PB3228), a wheat-Agropyron cristatum germplasm, exhibits a notably higher GNS. RESULTS: In this study, we developed a recombinant inbred line (RIL) population derived from PB3228/Gao8901 (PG-RIL) and constructed a high-density genetic map comprising 101,136 loci, spanning 4357.3 cM using the Wheat 660 K SNP array. The genetic map demonstrated high collinearity with the wheat assembly IWGSC RefSeq v1.0. Traits related to grain number and spikelet number per spike were evaluated in seven environments for quantitative trait locus (QTL) analysis. Five environmentally stable QTLs were detected in at least three environments. Among these, two major QTLs, QGns-4A.2 and QGns-1A.1, associated with GNS, exhibited positive alleles contributed by PB3228. Further, the conditional QTL analysis revealed a predominant contribution of PB3228 to the GNS QTLs, with both grain number per spikelet (GNSL) and spikelet number per spike (SNS) contributing to the overall GNS trait. Four kompetitive allele-specific PCR (KASP) markers that linked to QGns-4A.2 and QGns-1A.1 were developed and found to be effective in verifying the QTL effect within a diversity panel. Compared to previous studies, QGns-4A.2 exhibited stability across different trials, while QGns-1A.1 represents a novel QTL. The results from unconditional and conditional QTL analyses are valuable for dissecting the genetic contribution of the component traits to GNS at the individual QTL level and for understanding the genetic basis of the superior grain number character in PB3228. The KASP markers can be utilized in marker-assisted selection for enhancing GNS. CONCLUSIONS: Five environmentally stable QTLs related to grain number and spikelet number per spike were identified. PB3228 contributed to the majority of the QTLs associated with GNS.
Subject(s)
Agropyron , Triticum , Triticum/genetics , Agropyron/genetics , Chromosome Mapping , Phenotype , Quantitative Trait Loci/genetics , Edible Grain/genetics , Genetic LinkageABSTRACT
The genus Agropyron has an important role in soil protection and forage production in rangelands. The investigation utilized 37 ISSR primers, resulting in the detection of 956 loci within the A. elongatum genome and 705 loci within the A. cristatum genome. The findings revealed a high level of polymorphism, with 97% of loci in A. elongatum and 84% of loci in A. cristatum exhibiting variability. Notably, the primer (AC)8GCT emerged as a promising candidate for evaluating genetic diversity due to its ability to amplify numerous loci in both species. Using both the UPGMA algorithm and Bayesian analysis, the examined Agropyron accessions were categorized into two subgroups based on their respective species. The Q values associated with these subgroups suggested that certain accessions, namely "G16," "G19," "G20," "G21," "G22," "G23," "G24," and "G25," displayed potential admixture genomes. An analysis of molecular variance (AMOVA) underscored the significance of within-species variability, which accounted for 69% of the overall diversity, compared to between-species variability at 31%. Various genetic diversity parameters, including Na, Ne, I, He, and the number of private loci, were found to be higher in A. elongatum when compared to A. cristatum. Furthermore, Jaccard similarity coefficients ranged from 0.33 to 0.66 in A. cristatum and from 0.25 to 0.7 in A. elongatum, indicating the extent of genetic relatedness among these species. Intriguingly, the study identified two and three heterotic groups in A. cristatum and A. elongatum, respectively, which could be harnessed in the development of synthetic varieties to exploit heterosis. The results also indicated that a small proportion of ISSR loci pairs (5.2% in A. elongatum and 0.5% in A. cristatum) exhibited significant levels of linkage disequilibrium (LD) (P≤0.05), suggesting the potential utility of LD-based association mapping in Agropyron species. In conclusion, this research sheds light on the genetic diversity of Agropyron species and provides valuable insights into their potential applications in soil protection and forage production, as well as the prospects for enhancing genetic variability and heterosis in these species.
Subject(s)
Agropyron , Agropyron/genetics , Gene Pool , Iran , Bayes Theorem , Poaceae , SoilABSTRACT
To clarify the alleviation effect of exogenous melatonin (MT) on Agropyron mongolicum under drought stress, we examined the response of A. mongolicum 'Yanchi' seedlings to simulated drought stress with polyethylene glycol 6000 (PEG-6000), by investigating the effects of exogenous addition of different concentrations (0, 1, 10, 50, 100, 150 and 200 mg·L-1) of MT on seedlings growth and physiological characteristics under drought stress. The results showed that drought stress significantly inhibited the growth of A. mongolicum seedlings, and that exogenous addition of different concentrations of MT could alleviate the growth inhibition caused by drought stress, with the strongest mitigation effect observed at MT concentration of 100 mg·L-1. Compared with the drought stress treatment alone, exogenous addition of 100 mg·L-1 MT under drought stress increased plant height, aboveground dry weight, and leaf relative water content by 58.2%, 121.2% and 48.1%. The contents of chlorophyll a, chlorophyll b, carotenoids increased by 48.7%, 80.8% and 38.3%, superoxide dismutase, peroxidase and root activity increased by 12.6%, 33.9% and 39.1%, and the contents of ascorbic acid and glutathione increased by 19.5% and 18.3%, respectively. The contents of proline, soluble sugar and soluble protein were increased by 16.2%, 32.6% and 14.3%, while that of malondialdehyde, hydrogen peroxide and superoxide anion radical were decreased by 45.8%, 65.8% and 30.8%, respectively. In summary, exogenous addition of 100 mg·L-1 MT could improve drought tolerance of A. mongolicum seedlings by promoting growth, enhancing antioxidant capacity, increasing the content of osmoregulation substances, inhibiting the excessive production of reactive oxygen, and reducing membrane peroxide level.
Subject(s)
Agropyron , Melatonin , Melatonin/pharmacology , Seedlings , Agropyron/metabolism , Droughts , Chlorophyll A/metabolism , Stress, Physiological , Antioxidants/metabolism , Superoxides/metabolism , Superoxides/pharmacologyABSTRACT
Wild relatives of wheat are essential gene pools for broadening the genetic basis of wheat. Chromosome rearrangements and genomic variation in alien chromosomes are widespread. Knowledge of the genetic variation between alien homologous chromosomes is valuable for discovering and utilizing alien genes. In this study, we found that 5113 and II-30-5, two wheat-A. cristatum 6P addition lines, exhibited considerable differences in heading date, grain number per spike, and grain weight. Genome resequencing and transcriptome analysis revealed significant differences in the 6P chromosomes of the two addition lines, including 143,511 single-nucleotide polymorphisms, 62,103 insertion/deletion polymorphisms, and 757 differentially expressed genes. Intriguingly, genomic variations were mainly distributed in the middle of the chromosome arms and the proximal centromere region. GO and KEGG analyses of the variant genes and differentially expressed genes showed the enrichment of genes involved in the circadian rhythm, carbon metabolism, carbon fixation, and lipid metabolism, suggesting that the differential genes on the 6P chromosome are closely related to the phenotypic differences. For example, the photosynthesis-related genes PsbA, PsbT, and YCF48 were upregulated in II-30-5 compared with 5113. ACS and FabG are related to carbon fixation and fatty acid biosynthesis, respectively, and both carried modification variations and were upregulated in 5113 relative to II-30-5. Therefore, this study provides important guidance for cloning desirable genes from alien homologous chromosomes and for their effective utilization in wheat improvement.
Subject(s)
Agropyron , Agropyron/genetics , Hybridization, Genetic , Chromosomes, Plant/genetics , Phenotype , GenomicsABSTRACT
Background: The nitrogen (N) and protein concentrations in plant tissues exposed to elevated CO2 (eCO2) generally decline , such declines in forage grass composition are expected to have negative implications for the nutritional and economic value of grass. Plants require N for the production of a photosynthetically active canopy and storage proteins in the tissues, whose functionality will strongly influence productivity and quality. The objective of this study was to investigate whether eCO2 plus N-fertilization increases growth and N nutrition of Agropyron mongolicum, and the dependence of this improvement on the coordination between root and leaf development. Methods: We analyzed A. mongolicum from field-grown within the open-top chambers (OTCs) facility under two atmospheric CO2 (ambient, 400 ± 20 µmol mol-1, aCO2, and elevated, 800 ± 20 µmol mol-1, eCO2) and three N-fertigation treatments (control, low N-fertigation , and high N-fertigation) for two months. Results: Elevated CO2 plus N-fertigation strongly increased shoot and root biomass, and the nitrogen and protein concentrations of A. mongolicum compared to those plants at aCO2 levels. Increased N content in leaves and reduced specific leaf area (SLA) at a high N supply could alleviate photosynthetic acclimation to eCO2 and drive the production of greater shoot biomass with the potential for higher photosynthesis, productivity, and nutritional quality. The increased root length (RL), the ratio of total aboveground N taken up per RL (TN/RL), stomatal conductance (Gs), and transpiration rate (Tr) contribute to the transpiration-driven mass flow of N, consequently increasing N uptake by roots. In addition, a smaller percentage of N remained as unassimilated nitrate ( NO 3 - ) under eCO2, indicating that assimilation of NO 3 - into proteins was not inhibited by eCO2. These findings imply that grass productivity and quality will enhance under anticipated elevated CO2 concentration when effective management measures of N-fertilization are employed.
Subject(s)
Agropyron , Agropyron/metabolism , Carbon Dioxide/metabolism , Nitrogen/metabolism , Photosynthesis , Poaceae/metabolism , FertilizationABSTRACT
Agropyron repens (L.) P. Beauv. (couch grass) is a world-wide infesting rhizomatous plant with pharmacological applications. Chemical research is focused on its allelopathic and anti-inflammatory components, which are mainly present in the essential oil. Conversely, the aqueous extracts have been sparingly investigated, although the herbal tea is by far the most used formulation. To fill the gap, the metabolic profile of Agropyron repens rhizome herbal tea was investigated by electrospray ionization (ESI) tandem-mass spectrometry (MS/MS); the phenolic profile was investigated by HPLC-PDA-ESI-MS/MS. ESI-MS fingerprinting was provided, evidencing diagnostic ions for saccharides, organic acids and amino acids. The HPLC-PDA-ESI-MS/MS analysis evidenced at least 20 characteristic phenolic compounds, the most representative being caffeoyl and feruloyl quinic esters, followed by coumaric, caffeic and ferulic acids, and hesperidin among flavonoids. In addition, the essential amino acid tryptophan was identified for the first time. The results suggest new perspectives of applications for Agropyron repens rhizome.
Subject(s)
Agropyron , Teas, Herbal , Chromatography, High Pressure Liquid/methods , Flavonoids/chemistry , Metabolome , Phenols/analysis , Plant Extracts/chemistry , Rhizome/chemistry , Spectrometry, Mass, Electrospray Ionization/methods , Tandem Mass Spectrometry/methods , Teas, Herbal/analysisABSTRACT
KEY MESSAGE: The powdery mildew resistance locus was mapped to A. cristatum chromosome 6PL bin (0.27-0.51) and agronomic traits evaluation indicated that this locus has potential breeding application value. Agropyron cristatum (2n = 4x = 28, PPPP) is a wild relative of wheat with an abundance of biotic and abiotic stress resistance genes and is considered one of the best exogenous donor relatives for wheat breeding. A number of wheat-A. cristatum derived lines have been generated, including addition lines, translocation lines and deletion lines. In this study, the 6P disomic addition line 4844-12 (2n = 2x = 44) was confirmed to have genetic effects on powdery mildew resistance. Four 6P deletion lines (del16a, del19b, del21 and del27) and two translocation lines (WAT638a and WAT638b), derived from radiation treatment of 4844-12, were used to further assess the 6P powdery mildew resistance locus by powdery mildew resistance assessment, genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH) and 6P specific sequence-tagged-site (STS) markers. Collectively, the locus harboring the powdery mildew resistance gene was genetically mapped to a 6PL bin (0.27-0.51). The genetic effects of this chromosome segment on resistance to powdery mildew were further confirmed by del16a and del27 BC3F2 lines. Comprehensive evaluation of agronomic traits revealed that the powdery mildew resistance locus of 6PL (0.27-0.51) has potential application value in wheat breeding. A total of 22 resistant genes were annotated and 3 specific gene markers were developed for detecting chromatin of the resistant region based on genome re-sequencing. In summary, this study could broaden the powdery mildew resistance gene pool for wheat genetic improvements.
Subject(s)
Agropyron , Agropyron/genetics , Chromosomes, Plant/genetics , Disease Resistance/genetics , In Situ Hybridization, Fluorescence , Plant Breeding , Plant Diseases/genetics , Translocation, Genetic , Triticum/geneticsABSTRACT
Wheat leaf rust (caused by Puccinia triticina Erikss.) is among the major diseases of common wheat. The lack of resistance genes to leaf rust has limited the development of wheat cultivars. Wheat-Agropyron cristatum (A. cristatum) 2P addition line II-9-3 has been shown to provide broad-spectrum immunity to leaf rust. To identify the specific A. cristatum resistance genes and related regulatory pathways in II-9-3, we conducted a comparative transcriptome analysis of inoculated and uninoculated leaves of the resistant addition line II-9-3 and the susceptible cultivar Fukuhokomugi (Fukuho). The results showed that there were 66 A. cristatum differentially expressed genes (DEGs) and 1389 wheat DEGs in II-9-3 during P. triticina infection. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and gene set enrichment analysis (GSEA) revealed that the DEGs of II-9-3 were associated with plant-pathogen interaction, MAPK signaling pathway-plant, plant hormone signal transduction, glutathione metabolism, and phenylpropanoid biosynthesis. Furthermore, many defense-related A. cristatum genes, such as two NLR genes, seven receptor kinase-encoding genes, and four transcription factor-encoding genes, were identified. Our results indicated that the key step of resistance to leaf rust involves, firstly, the gene expression of chromosome 2P upstream of the immune pathway and, secondly, the effect of chromosome 2P on the co-expression of wheat genes in II-9-3. The disease resistance regulatory pathways and related genes in the addition line II-9-3 thus could play a critical role in the effective utilization of innovative resources for leaf rust resistance in wheat breeding.
Subject(s)
Agropyron , Basidiomycota , Agropyron/genetics , Basidiomycota/genetics , Chromosomes, Plant , Disease Resistance/genetics , Gene Expression Profiling , Plant Breeding , Plant Diseases/genetics , Transcriptome , Triticum/geneticsABSTRACT
KEY MESSAGE: Analysis of multi-year breeding program data revealed that the genetic architecture of an intermediate wheatgrass population was highly polygenic for both domestication and agronomic traits, supporting the use of genomic selection for new crop domestication. Perennial grains have the potential to provide food for humans and decrease the negative impacts of annual agriculture. Intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza®) is a promising perennial grain candidate that The Land Institute has been breeding since 2003. We evaluated four consecutive breeding cycles of IWG from 2016 to 2020 with each cycle containing approximately 1100 unique genets. Using genotyping-by-sequencing markers, quantitative trait loci (QTL) were mapped for 34 different traits using genome-wide association analysis. Combining data across cycles and years, we found 93 marker-trait associations for 16 different traits, with each association explaining 0.8-5.2% of the observed phenotypic variance. Across the four cycles, only three QTL showed an FST differentiation > 0.15 with two corresponding to a decrease in floret shattering. Additionally, one marker associated with brittle rachis was 216 bp from an ortholog of the btr2 gene. Power analysis and quantitative genetic theory were used to estimate the effective number of QTL, which ranged from a minimum of 33 up to 558 QTL for individual traits. This study suggests that key agronomic and domestication traits are under polygenic control and that molecular methods like genomic selection are needed to accelerate domestication and improvement of this new crop.
Subject(s)
Agropyron , Quantitative Trait Loci , Agropyron/genetics , Domestication , Edible Grain/genetics , Genome-Wide Association Study , Humans , Plant Breeding/methods , Selection, GeneticABSTRACT
In turfgrass breeding, competent grass ecotypes are preferably identified for their resistance to salinity condition. This research was designed to explore genes that induce salt resistance (NHX1, NHX2, HKT1;4, SnRK2.4 and NAC9) and their role in physiological modifications of six tall wheatgrass ecotypes (Agropyron elongatum L.). The sites of sample collection were characterized by different levels of salinity, i.e. low (EC: 4 dS m-1 and pH: 6.5), moderate (EC: 7 dS m-1 and pH: 6.5) and high (EC: 12 dS m-1 and pH: 7.5). This study was designed as a split-plot in a randomized complete block where salinity treatments served as the whole-plot factor and ecotypes served as the subplot factor. The ecotypes were screened for their resistance to salinity, based on visual symptoms, salt injury index, physiological features and biochemical parameters. The results revealed that ecotype 'AE5' was most resistant to salinity than other ecotypes, whereas 'AE3' was the most susceptible. To understand why these differences occurred, measurements were aimed at revealing mRNA levels that resulted from genes responsible for salt resistance. Our results demonstrated that salinity-resistant ecotypes showed high expression levels of several genes, i.e. NHX1, NHX2, HKT1;4, SnRK2.4 and NAC9 in the leaves and roots. These results were corroborated by a decrease (by 1.5-2.5 times) in stress markers, namely, superoxide anion (O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA), as well as an increase (by 0.5-7 times) in enzymatic and non-enzymatic antioxidant activity in salinity-resistant ecotypes when the plants were exposed to salinity. We observed higher values of initial root length and lateral root density (21% and 18%, respectively) in salinity-resistant ecotypes under salinity condition, compared to other ecotypes. There were lower expression levels of NHX1 and NHX2 in the roots, which were 3.2 and 2.1 times less, respectively, compared to the leaves. This implied that NHX1 and NHX2 expressions can lead to the sequestration of Na+ in the leaves during salinity condition. The current research revealed that HKT1;4 was more able to restrict Na + accumulation, compared to the actions of NHX1 and NHX2 genes. The over-expression of HKT1;4 in 'AE5' allowed a better maintenance of root growth during salinity condition. The expression of NAC9 had an increase of 2.1-fold which correlated with an increase in the amount of antioxidant enzymes. In general, the location of sample collection explained the differences in gene expression, especially regarding the extent to which plants respond to salinity condition. Ultimately, these differences can define physiological features in salinity-resistant and salinity-susceptible ecotypes of tall wheatgrass.
Subject(s)
Agropyron , Salt Tolerance , Agropyron/genetics , Agropyron/metabolism , Gene Expression , Hydrogen Peroxide/metabolism , Ions/metabolism , Plant Breeding , Plant Leaves/genetics , Plant Leaves/metabolism , Plant Roots/genetics , Plant Roots/metabolism , Poaceae/genetics , Poaceae/metabolism , Reactive Oxygen Species/metabolism , Salinity , Salt Stress/genetics , Salt Tolerance/genetics , Sodium/metabolismABSTRACT
KEY MESSAGE: Introducing Agropyron cristatum chromosome 1P into common wheat can significantly reduce the plant height and leaf size, which can improve the plant architecture of common wheat. A new direction in crop breeding is the improvement of plant architecture for dense plantings to obtain higher yields. Wild relatives carry an abundant genetic variation that can increase the diversity of genes for crop genetic improvement. In this study, the A. cristatum 1P addition line, 1PS and 1PL telosomic addition lines were obtained by backcrossing the addition/substitution line II-3-1 (2n = 20'' W + 1P" + 2P") with the commercial recurrent parent cv. Jimai 22. Four continuous years of agronomic trait investigation in the genetic populations suggested that the introduction of A. cristatum chromosome 1P into wheat can significantly improve wheat plant architecture by reducing the plant height, leaf length and leaf width. A. cristatum chromosome arm 1PS reduced the plant height and leaf length of wheat, whereas introducing A. cristatum chromosome arm 1PL reduced the plant height, leaf length and leaf width. Altogether, our results demonstrated that A. cristatum chromosome 1P carries the dominant genes for small leaves and a dwarf habit for the enhancement of plant architecture in wheat. This study highlights wild relative donors as new gene resources for improving wheat plant architecture for dense planting.
Subject(s)
Agropyron , Agropyron/genetics , Chromosomes, Plant/genetics , Hybridization, Genetic , Plant Breeding , Plant Leaves/genetics , Translocation, Genetic , Triticum/geneticsABSTRACT
BACKGROUND: Intermediate wheatgrass (IWG) is a novel perennial grain crop currently undergoing domestication. It offers important ecosystem benefits while producing grain suitable for human consumption. Several aspects of plant biology and genetic control are yet to be studied in this new crop. To understand trait behavior and genetic characterization of kernel color in IWG breeding germplasm from the University of Minnesota was evaluated for the CIELAB components (L*, a*, b*) and visual differences. Trait values were used in a genome-wide association scan to reveal genomic regions controlling IWG's kernel color. The usability of genomic prediction in predicting kernel color traits was also evaluated using a four-fold cross validation method. RESULTS: A wide phenotypic variation was observed for all four kernel color traits with pairwise trait correlations ranging from - 0.85 to 0.27. Medium to high estimates of broad sense trait heritabilities were observed and ranged from 0.41 to 0.78. A genome-wide association scan with single SNP markers detected 20 significant marker-trait associations in 9 chromosomes and 23 associations in 10 chromosomes using multi-allelic haplotype blocks. Four of the 20 significant SNP markers and six of the 23 significant haplotype blocks were common between two or more traits. Evaluation of genomic prediction of kernel color traits revealed the visual score to have highest mean predictive ability (r2 = 0.53); r2 for the CIELAB traits ranged from 0.29-0.33. A search for candidate genes led to detection of seven IWG genes in strong alignment with MYB36 transcription factors from other cereal crops of the Triticeae tribe. Three of these seven IWG genes had moderate similarities with R-A1, R-B1, and R-D1, the three genes that control grain color in wheat. CONCLUSIONS: We characterized the distribution of kernel color in IWG for the first time, which revealed a broad phenotypic diversity in an elite breeding germplasm. Identification of genetic loci controlling the trait and a proof-of-concept that genomic selection might be useful in selecting genotypes of interest could help accelerate the breeding of this novel crop towards specific end-use.
Subject(s)
Agropyron , Genome-Wide Association Study , Agropyron/genetics , Chromosome Mapping , Ecosystem , Edible Grain/genetics , Genomics , Plant Breeding , Poaceae/geneticsABSTRACT
Crested wheatgrass (Agropyron cristatum), a wild relative of wheat, is an attractive source of genes and alleles for their improvement. Its wider use is hampered by limited knowledge of its complex genome. In this work, individual chromosomes were purified by flow sorting, and DNA shotgun sequencing was performed. The annotation of chromosome-specific sequences characterized the DNA-repeat content and led to the identification of genic sequences. Among them, genic sequences homologous to genes conferring plant disease resistance and involved in plant tolerance to biotic and abiotic stress were identified. Genes belonging to the important groups for breeders involved in different functional categories were found. The analysis of the DNA-repeat content identified a new LTR element, Agrocen, which is enriched in centromeric regions. The colocalization of the element with the centromeric histone H3 variant CENH3 suggested its functional role in the grass centromere. Finally, 159 polymorphic simple-sequence-repeat (SSR) markers were identified, with 72 of them being chromosome- or chromosome-arm-specific, 16 mapping to more than one chromosome, and 71 mapping to all the Agropyron chromosomes. The markers were used to characterize orthologous relationships between A. cristatum and common wheat that will facilitate the introgression breeding of wheat using A. cristatum.