RS Translocation Research Articles

Genetic Diversity of Promising Spring Wheat Accessions from Russia and Kazakhstan for Rust Resistance.

Spring bread wheat (Triticum aestivum) is a major crop in Russia and in Kazakhstan. The rust pathogens, leaf rust caused by the fungus Puccinia triticina, stem rust incited by P. graminis and yellow rust caused by P. striiformis, are the significant biotic factors affecting wheat production. In this study, 40 new promising spring wheat genotypes from the Kazakhstan-Siberia Network for Spring Wheat Improvement (KASIB) were tested for resistance to leaf, stem and yellow rust at the seedling stage, and for identification of rust resistance genes using molecular markers. In addition, the collection was tested for leaf rust resistance and grain yields in the South Urals agroclimatic zone of Russia in 2023. As a result, 16 accessions with seedling resistance to leaf rust, 21 to stem rust and 4 to yellow rust were identified. Three breeding accessions were resistant to all rust species, and nine to P. triticina and P. graminis. Wheat accessions resistant to leaf rust at the seedling stage were also resistant in the field. Molecular analysis showed the presence of cataloged resistance genes, Lr1, Lr3a, Lr9, Lr10, Lr19, Lr20, Lr24, Lr26, Sr15, Sr24, Sr25, Sr31, Sr38, Yr9 and Yr18; uncatalogued genes Lr6Agi1 and Lr6Agi2 from Thinopyrum intermedium and LrAsp from Aegilops speltoides; and 1AL.1RS translocation. The current analysis showed an increase in leaf and stem rust resistance of new KASIB genotypes and their genetic diversity due to the inclusion of alien genetic material in breeding.

A study of the influence of the T2DL.2DS-2SS translocation and the 5S(5D) substitution from Aegilops speltoides on breeding-valuable traits of common wheat.

The use of the gene pool of wild relatives for expanding the genetic diversity of common wheat is an important task of breeding programs. However, the practical application of common wheat lines with alien genetic material is constrained by the lack of information on chromosomal rearrangements and the negative impact of the transferred material on agronomically important traits. This research is aimed at studying 14 introgression lines with the T2DL.2DS-2SS translocation and the 5S(5D) substitution from Aegilops speltoides obtained from crossing common wheat varieties (Aurora, Krasnodarskaya 99, Nika Kubani) with the genome-substituted form Avrodes (BBAASS). Hybrid lines with different combinations of T2DL.2DS-2SS and T1BL.1RS translocations and 5S(5D) substitution were characterized by resistance to leaf and yellow rusts, productivity components and technological qualities of grain. The assessment of the varieties' resistance to rust diseases showed that Krasnodarskaya 99, Nika Kubani and the Aurora variety, which is a carrier of the T1BL.1RS translocation, are highly susceptible to diseases, while the presence of the T2DL.2DS-2SS translocation and the 5S(5D) substitution, both together and separately, provides resistance to fungal pathogens. The analysis of the lines using markers designed for known resistance genes of Ae. speltoides did not reveal the presence of the Lr28, Lr35 and Lr51 genes in the lines. The results suggest that the genetic material of Ae. speltoides transferred to chromosomes 2D and 5D contains new resistance genes. To determine the effect of the T2DL.2DS-2SS translocation and the 5S(5D) substitution on the productivity and technological qualities of grain, the lines were assessed by weight of 1000 grains, grain weight and number of ears per 1 m2, by protein and gluten content, gluten quality and general baking evaluation. A positive effect was determined upon the weight of 1000 grains, protein and gluten content. There were no significant differences in other characteristics. The T2DL.2DS-2SS translocation and the 5S(5D) substitution did not have a negative effect on the productivity and technological quality of grain, and are of interest for breeding practice.

Rye-durum wheat 1BL.1RS translocation: implications for drought tolerance and nutritional status.

The translocation of the short chromosome arm 1RS of rye onto the 1B chromosome of common wheat has been shown to improve resistance to stress and yield. Here, translocation was operated in durum wheat and its effects on drought tolerance were evaluated. Both the 1BL.1RS translocation line (Svevo 1BL.1RS) and the corresponding Svevo control were exposed to drought for 7 days. Significant differences were found in root morphology between Svevo and Svevo 1BL.1RS under control and drought conditions. Although Svevo 1BL.1RS experienced more severe growth inhibition due to drought than Svevo, it exhibited greater resilience to oxidative stress. Furthermore, several drought-responsive genes were upregulated in both shoots and roots only in the translocation line. Notably, in roots of Svevo 1BL.1RS, the expression of these genes was also higher in the control condition compared to Svevo, suggesting that these genes could be constitutively expressed at higher levels in the translocation line. Moreover, the 1BL.1RS translocation had a significant impact on the plant's ability to accumulate nutrients under drought. Overall, the impact on sulfate accumulation and the expression of genes associated with its assimilation pathways are particularly noteworthy, highlighting the involvement of sulfur in the plant response to water stress. Additionally, the genetic characterization of Svevo 1BL.1RS revealed variants extending beyond the translocation, located in drought stress-responsive genes.

Genetic Analysis of Stripe Rust Resistance in the Chinese Wheat Cultivar Luomai 163.

Stripe or yellow rust (YR) caused by Puccinia striiformis tritici (Pst) is an important foliar disease affecting wheat production globally. Resistant varieties are the most economically and environmentally effective way to manage this disease. The common winter wheat (Triticum aestivum L.) cultivar Luomai 163 exhibited resistance to Pst races CYR32 and CYR33 at the seedling stage and showed a high level adult plant resistance in the field. To understand the genetic basis of YR resistance in this cultivar, 142 F5 recombinant inbred lines (RILs) derived from cross Apav#1 × LM163 and both parents were genotyped with the 16K SNP array and bulked segregant analysis sequencing (BSA-Seq). The analysis detected a major gene, YrLM163, at the seedling stage associated with the 1BL.1RS translocation. Additionally, three genes for resistance at the adult plant stage were detected on chromosome arms 1BL (Lr46/Yr29/Pm39/Sr58), 6BS and 6BL in Luomai 163, whereas Apav#1 contributed resistance at a QTL on 2BL. These QTL explained YR disease severity variations ranging from 6.9 to 54.8%. KASP markers KASP-2BL, KASP-6BS and KASP-6BL for three novel loci QYr.hzau-2BL, QYr.hzau-6BS and QYr.hzau-6BL were developed and validated. QYr.hzau-1BL, QYr.hzau-2BL and QYr.hzau-6BS showed varying degrees of resistance to YR when present individually or in combination based on genotype and phenotype analysis of a panel of 570 wheat accessions. Six RILs combining resistance alleles of all QTL, showing higher resistance to YR in the field than Luomai 163 with disease severities of 10.7-16.0%, are important germplasm resources for breeding programs to develop YR resistant wheat varieties with good agronomic traits.

Grain albumin content is affected by 1BL/1RS translocation and alters the processing quality of wheat (Triticum aestivum L.).

Grain albumin is highly nutritious and closely related to the processing quality of wheat. However, few studies have explored the grain albumin content (GAC) in wheat. This study aims to uncover quantitative trait loci (QTLs) linked to wheat GAC by analyzing a doubled haploid (DH) population derived from common wheat cultivars ShanNong23 and ZhouMai17. We detected six QTLs controlling GAC on chromosomes 1B, 5A, and 6D, with individual QTL explaining 5.78% to 22.29% of the GAC variation. The effect of QGac.cau-1B.1 on GAC is attributed to the presence of the 1BL/1RS translocation, indicating that the 1BL/1RS translocation increase of GAC compared with the non-1BL/1RS translocation lines. The higher GAC observed in 1BL/1RS lines could be primarily attributed to the increased accumulation of omega-secalin, omega-gliadin, low molecular weight glutenin subunit and ribosomal protein content. Additionally, we also found that the SDS-sedimentation value of whole wheat flour was decreased by adding albumin solution. These results advance our understanding of the genetic basis of GAC and offer novel perspectives for enhancing wheat quality through genetic enhancements.

Genetic mapping of loci affecting seedling and adult-plant resistance to powdery mildew derived from two CIMMYT wheat lines

Main conclusionPM3 and PM8 alleles carried by two CIMMYT wheat lines confer powdery mildew resistance in seedlings and/or adult plants. A stage-specific epistatic interaction was observed between PM3 and PM8.Powdery mildew is an important foliar disease of wheat. Major genes for resistance, which have been widely used in wheat breeding programs, are typically effective against only limited numbers of virulence genes of the pathogen. The main aim of this study was to map resistance loci in wheat lines 7HRWSN58 and ZWW09-149 from the International Maize and Wheat Improvement Center (CIMMYT). Doubled haploid populations (Magenta/7HRWSN58 and Emu Rock/ZWW09-149) were developed and grown in controlled environment experiments and inoculated with a composite of Blumeria graminis f.sp. tritici isolates that had been collected at various locations in Western Australia. Plants were assessed for powdery mildew symptoms (percentage leaf area diseased) on seedlings and adult plants. Populations were subjected to genotyping-by-sequencing and assayed for known SNPs in the resistance gene PM3. Linkage maps were constructed, and markers were anchored to the wheat reference genome sequence. In both populations, there were asymptomatic lines that exhibited no symptoms. Among symptomatic lines, disease severity varied widely. In the Magenta/7HRWSN58 population, most of the observed variation was attributed to the PM3 region of chromosome 1A, with the allele from 7HRWSN58 conferring resistance in seedlings and adult plants. In the Emu Rock/ZWW09-149 population, two interacting quantitative trait loci were mapped: one at PM3 and the other on chromosome 1B. The Emu Rock/ZWW09-149 population was confirmed to segregate for a 1BL·1RS translocation that carries the PM8 powdery mildew resistance gene from rye. Consistent with previous reports that PM8-derived resistance can be suppressed by PM3 alleles, the observed interaction between the quantitative trait loci on chromosomes 1A and 1B indicated that the PM3 allele carried by ZWW09-149 suppresses PM8-derived resistance from ZWW09-149, but only at the seedling stage. In adult plants, the PM8 region conferred resistance regardless of the PM3 genotype. The resistance sources and molecular markers that were investigated here could be useful in wheat breeding.

Effects of the 1RS.1BL wheat-rye translocationon kernel and bran content of bread wheat (Triticum aestivum L.)

In this study, the effects of rye translocation on some quality properties and mineral content of whole wheat kernel and bran were investigated.The plant material consisted of 147 recombinant inbred lines (RILs) and five control cultivars, including the parent. The genotypes were grown in Turkey at two different locations for two consecutive years. In the study, lines with and without rye translocation were determined by SDS-PAGE and PCR analysis, and the glutenin subunits of the lines at Glu-A1, Glu-B1, Glu-A3 and Glu-B3 loci were also analyzed. The protein, starch, fat, ash, dry matter, acid detergent insoluble fiber (ADF), neutral detergent insoluble fiber (NDF), potassium (K), phosphorus (P) and magnesium (Mg) contents of kernels and bran of the RILs were determined. Statistically significant differences were found between the genotypes in terms of all the examined characteristics except the amount of dry matter. The RILs carrying translocation 1RS.1BLhad a higher average ADF, NDF, protein content, ash content, K, Mg, and P contents of kernels, as well as a higher average ADF, NDF, ash, and K bran contents than the RILs without thetranslocation. The bran of the RILs without thetranslocationhad higher values in terms of fat, starch, and phosphorus content. The results indicate that wheat- rye translocation1RS.1BL has a significant effect on both whole wheat kernel and bran content, and can be used to enrich the content of wheat bran.

Resistance of Modern Russian Winter Wheat Cultivars to Yellow Rust.

Over the last decade, the significance of yellow rust caused by Puccinia striiformis (Pst) has substantially increased worldwide, including in Russia. The development and cultivation of resistant genotypes is the most efficient control method. The present study was conducted to explore the yellow rust resistance potential of modern common winter wheat cultivars included in the Russian Register of Breeding Achievements in 2019-2022 using the seedling tests with an array of Pst races and molecular markers linked with Yr resistance genes. Seventy-two winter wheat cultivars were inoculated with five Pst isolates differing in virulence and origin. Molecular markers were used to identify genes Yr2, Yr5, Yr7, Yr9, Yr10, Yr15, Yr17, Yr18, Yr24, Yr25 and Yr60. Thirteen cultivars were resistant to all Pst isolates. The genes Yr5, Yr10, Yr15 and Yr24 that are effective against all Russian Pst races in resistant cultivars were not found. Using molecular methods, gene Yr9 located in translocation 1BL.1RS was detected in 12 cultivars, gene Yr18 in 24, gene Yr17 in 3 and 1AL.1RS translocation with unknown Yr gene in 2. While these genes have lost effectiveness individually, they can still enhance genetic diversity and overall yellow rust resistance, whether used in combination with each other or alongside other Yr genes.

The different subtelomeric structure among 1RS arms in wheat-rye 1BL.1RS translocations affecting their meiotic recombination and inducing their structural variation

BackgroundThe 1RS arm of wheat-rye 1BL.1RS translocations contains several subtelomeric tandem repeat families. To study the effect of the difference in the composition of these tandem repeats on the meiotic recombination of 1RS arms can help to enrich the genetic diversity of 1BL.1RS translocation chromosomes.ResultsFive wheat-rye 1BL.1RS translocation cultivars/lines were used to build two cross combinations including group 1 (20T401 × Zhou 8425B, 20T401 × Lovrin 10 and 20T401 × Chuannong 17) and group 2 (20T360-2 × Zhou 8425B, 20T360-2 × Lovrin 10 and 20T360-2 × Chuannong 17). Oligonucleotide (oligo) probes Oligo-s120.3, Oligo-TR72, and Oligo-119.2-2 produced the same signal pattern on the 1RS arms in lines 20T401 and 20T360-2, and another signal pattern in the three cultivars Zhou 8425B, Lovrin 10 and Chuannong 17. The Oligo-pSc200 signal disappeared from the 1RS arms of the line 20T401, and the signal intensity of this probe on the 1RS arms of the line 20T360-2 was weaker than that of the three cultivars. The five cultivars/lines had the same signal pattern of the probe Oligo-pSc250. The recombination rate of 1RS arms in group 1 was significantly lower than that in group 2. In the progenies from group 1, unequal meiotic recombination in the subtelomeric pSc119.2 and pSc250 tandem repeat regions, and a 1BL.1RS with inversion of 1RS segment between the pSc200 and the nucleolar organizer region were found.ConclusionsThis study provides a visual tool to detect the meiotic recombination of 1RS arms. The meiotic recombination rate of 1RS arms was affected by the variation of pSc200 tandem repeat, indicating the similar composition of subtelomeric tandem repeats on these arms could increase their recombination rate. These results indicate that the 1RS subtelomeric structure will affect its recombination, and thus the localization of genes on 1RS by means of meiotic recombination might also be affected.

Toward reducing the immunogenic potential of wheat flour: identification and characterization of wheat lines missing omega-5 gliadins encoded by the 1D chromosome.

Eleven wheat lines that are missing genes for the 1D-encoded omega-5 gliadins will facilitate breeding efforts to reduce the immunogenic potential of wheat flour for patients susceptible to wheat allergy. Efforts to reduce the levels of allergens in wheat flour that cause wheat-dependent exercise-induced anaphylaxis are complicated by the presence of genes encoding omega-5 gliadins on both chromosomes 1B and 1D of hexaploid wheat. In this study, we screened 665 wheat germplasm samples using gene specific DNA markers for omega-5 gliadins encoded by the genes on 1D chromosome that were obtained from the reference wheat Chinese Spring. Eleven wheat lines missing the PCR product corresponding to 1D omega-5 gliadin gene sequences were identified. Two of the lines contained the 1BL·1RS translocation. Relative quantification of gene copy numbers by qPCR revealed that copy numbers of 1D omega-5 gliadins in the other nine lines were comparable to those in 1D null lines of Chinese Spring, while copy numbers of 1B omega-5 gliadins were like those of Chinese Spring. 2-D immunoblot analysis of total flour proteins from the selected lines using a specific monoclonal antibody against the N-terminal sequence of omega-5 gliadin showed no reactivity in regions of the blots containing previously identified 1D omega-5 gliadins. Interestingly, RP-UPLC analysis of the gliadin fractions of the selected lines indicated that the expression of omega-1,2 gliadins was also significantly reduced in seven of the lines, implying that 1D omega-5 gliadin and 1D omega-1,2 gliadin genes are tightly linked on the Gli-D1 loci of chromosome 1D. Wheat lines missing the omega-5 gliadins encoded by the genes on 1D chromosome should be useful in future breeding efforts to reduce the immunogenic potential of wheat flour.

The perspective soft spring wheat variety Semenovna is the result of international cooperation

The research is aimed at studying economically valuable traits and genetic control of resistance to leaf-stem diseases, photoperiodic reaction and short stemming of soft spring wheat variety Semenovna, created by scientists of the Omsk Agrarian Scientific Center (Russia) and the North Kazakhstan Agricultural Experimental Station (Kazakhstan). Using methods of state variety testing, molecular genetics and in vitro methods, morphological features of a new variety, features of its development have been described, the yield level at different ecological test points for three years (2015-2017) has been analyzed. The studies conducted at two ecological points made it possible to select a medium-sized promising line of soft spring wheat (Lutescens 354/04-6), which was transferred to the State Registration Service of the Republic of Kazakhstan and after two years of testing was included into the State Register of the Republic of Kazakhstan under the name Semenovna (patent No. 1023). In terms of grain quality, it was at the level of valuable wheat, exceeded the standard in protein content by 1-2 % and raw gluten by 3-4 %. The new medium-ripe Semenovna variety combines increased yield (2.73-4.40 t/ha) with resistance to drought (resistance index Ir = 0.57), brown and stem rust (IU = 0.00-0.23). The genotype of the variety contains wheat-rye translocation 1RS.1BL (with a cluster of Lr26/Sr31/Pm8/Yr9 genes). The medium-stem variety carries the Rht8b allele in its genotype (174 bp) and is photosensitive to the length of the day (allele 414 bp). The parameters of ecological plasticity of the new variety are determined: linear regression coefficient (bi = 1.08), stability index (σd2 = 0.27).

Development of diagnostic SNP markers for identification of rye 1RS translocations in wheat

AbstractWheat (Triticum aestivum L.) wild relatives are rich genetic resources for genetic improvement of wheat. The short arm of rye (Secale cereale L.) chromosome 1 (1RS) contains many beneficial genes for resistance to drought, insects, and diseases, therefore the 1RS wheat translocations have been widely used in wheat breeding programs worldwide. To facilitate marker‐assisted identification of 1RS in wheat breeding, we designed a set of Kompetitive allele‐specific polymerase chain reaction (KASP) markers to detect the translocations of 1RS with long arm from wheat chromosome 1A (1RS.1AL) and 1RS with long arm from wheat chromosome 1B (1RS.1BL) based on the sequence flanking single nucleotide polymorphisms (SNPs) generated by genotyping‐by‐sequencing (GBS) between wheat and rye panels. We identified a set of three SNP markers for diagnosis and differentiation of the two 1RS translocations in wheat. Among the three KASP markers, 1AS‐05056 is 1RS specific, and clearly separated the genotypes with 1RS (1RS.1AL and 1RS.1BL) from those without the two 1RS translocations; whereas 1AS‐29875 clearly identified the 1RS.1AL translocation and 1BS‐16654 separated 1RS.1BL from 1RS.1AL. The three new KASP markers together accurately identified the presence of 1RS translocation on either 1A or 1B chromosome in a panel of 95 representative U.S. winter wheat accessions, which were further validated in two additional U.S. hard winter wheat panels. Therefore, they can be used for routine screening of 1RS.1BL and 1RS.1AL translocation lines in wheat breeding programs.

Centromere-Specific Single-Copy Sequences of Secale Species.

Single-copy FISH analysis is a useful tool to physically locate a given sequence on chromosome. Centromeric single-copy sequences can be used to locate the position of centromere and disclose the subtle differences among different centromeres. Nine centromeric single-copy sequences 1R1, 3R1, 4R1, 4R2, 5R1, 5R2, 6R2, 6R3, and 7R1 were cloned from Kustro (Secale cereale L.). FISH analysis using these sequences as probes indicated that the signals of 1R1, 3R1, 4R1, 4R2, 5R1, 5R2, 6R1, 6R2, and 7R1 were located in the centromeric regions of rye 1R, 3R, 4R, 4R, 5R, 5R, 6R, 6R, and 7R chromosomes, respectively. In addition, for each of the centromeric single-copy sequences, high sequence similarity was observed among different Secale species. Combined with rye genomic sequence, single-copy FISH analysis indicated that the 1BL.1RS translocations in wheat cultivar CN17 and wheat line 20T363-4 contained the centromeric segment of 1R chromosome from 349,498,361 to 349,501,266 bp, and the 1BL.1RS translocations in the other two wheat cultivars did not contain this segment. The nine sequences are useful in determining the centromere location on rye chromosomes, and they have the potential to disclose the accurate structural differences of centromeres among the wheat-rye centric fusion translocation chromosomes; therefore, more centromeric single-copy sequences are needed.

Development and characterization of a novel common wheat–Mexico Rye T1DL·1RS translocation line with stripe rust and powdery mildew resistance

Rye (Secale cereale L., 2n=2x=14, RR) is a significant genetic resource for improving common wheat because of its resistance to multiple diseases and abiotic-stress tolerant traits. The 1RS chromosome from the German cultivated rye variety Petkus is critical in wheat breeding. However, its weakened disease resistance highlights the need to identify new resources. In the present study, a novel derived line called D27 was developed from common wheat and Mexico Rye. Cytological observations characterized the karyotype of D27 as 2n=42=21 II. Genomic in situ hybridization indicated that a pair of whole-arm translocated Mexico Rye chromosomes were inherited typically in the mitotic and meiosis stages of D27. Experiments using fluorescence in situ hybridization (FISH) and gliadin electrophoresis showed that D27 lacked wheat 1DS chromosomes. They were replaced by 1RS chromosomes of Mexico Rye, supported by wheat simple-sequence repeat markers, rye sequence characterized amplified region markers, and wheat 40K SNP array analysis. The wheat 1DS chromosomes could not be detected by molecular markers and wheat SNP array, but the presence of rye 1RS chromosomes was confirmed. Agronomic trait assessments indicated that D27 had a higher tiller number and enhanced stripe rust and powdery mildew resistance. In addition, dough properties analysis showed that replacing 1DS led to higher viscosity and lower dough elasticity in D27, which was beneficial for cake making. In conclusion, the novel cytogenetically stable common wheat–Mexico Rye T1DL·1RS translocation line D27 offers excellent potential as outstanding germplasm in wheat breeding programs focusing on disease resistance and yield improvement. Additionally, it can be valuable for researching the rye 1RS chromosome’s genetic diversity.

Efficiency of using of wheat-rye translocations (WRT) 1AL/1RS and 1BL/1RS in soft winter wheat breeding

Purpose. To determine the genetic effects of WRT 1AL.1RS and 1BL.1RS on the yield, plant productivity elements and quality indices of recombinant lines, to determine the effectiveness of using each of the WRT for creating more perfect varieties of soft winter wheat in these traits under soil-air drought in the steppe zone of Ukraine and development of breeding techniques to reduce the negative effects of translocation to produce genotypes with high quality indices of valuable and strong wheat grain. Methods. Field experiments, intraspecific hybridization, evaluation of breeding material in the field, methods of laboratory determination of baking quality indices of grain, electrophoresis of spare proteins, statistical. Results. Under arid conditions of the South of Ukraine on the large experimental material of breeding process, a positive effect of 1AL.1RS on the yield of recombinant lines and the main elements of plant productivity were determined, which was manifested against the background of simultaneous positive effect of this transposition on the drought and heat tolerance. The use of 1BL.1RS in wheat breeding in this region is less promising technique. It has been determined that introduction of 1AL.1RS, 1BL.1RS translocations into local gene pool of soft winter wheat by hybridization changes the grain quality indices. In particular, the protein content tends to increase more significantly under the influence of 1BL.1RS translocation. It has been shown that the frequency of obtaining recombinant lines which combine high yield and sufficient level of baking properties (not lower than valuable and strong wheat) is quite low (1,7–6,1%), but introgressive lines with 1AL.1RS have the advantages in this parameter. Using such genetic factors as hybridization combining WRT with alleles with high positive effect on baking properties, and also creating heterogeneity in the composition of genotypes with and without WRT, one can purposefully reduce the negative impact of WRT on the quality of soft winter wheat grain and create varieties with quality parameters of valuable and strong wheat. Conclusions. In general, the results achieved give reason to assert that the use of WRT 1AL.1RS is a promising direction for further breeding increase of genetic capacity of soft winter wheat varieties in the arid conditions of the South of Ukraine. As a result of full cycle of breeding process on the material with 1AL.1RS WRT a series of varieties of soft winter wheat ‘Zhytnytsia odeska’, ‘Oktava odeska’, ‘Liha odeska’, ‘Duma odeska’, ‘Versiia odeska’, providing 10 – 15% increase in yield to standards was created and included in the State Register of Ukraine and Moldova.

Ancient variation of the AvrPm17 gene in powdery mildew limits the effectiveness of the introgressed rye Pm17 resistance gene in wheat

Introgressions of chromosomal segments from related species into wheat are important sources of resistance against fungal diseases. The durability and effectiveness of introgressed resistance genes upon agricultural deployment is highly variable-a phenomenon that remains poorly understood, as the corresponding fungal avirulence genes are largely unknown. Until its breakdown, the Pm17 resistance gene introgressed from rye to wheat provided broad resistance against powdery mildew (Blumeria graminis). Here, we used quantitative trait locus (QTL) mapping to identify the corresponding wheat mildew avirulence effector AvrPm17. It is encoded by two paralogous genes that exhibit signatures of reoccurring gene conversion events and are members of a mildew sublineage specific effector cluster. Extensive haplovariant mining in wheat mildew and related sublineages identified several ancient virulent AvrPm17 variants that were present as standing genetic variation in wheat powdery mildew prior to the Pm17 introgression, thereby paving the way for the rapid breakdown of the Pm17 resistance. QTL mapping in mildew identified a second genetic component likely corresponding to an additional resistance gene present on the 1AL.1RS translocation carrying Pm17. This gene remained previously undetected due to suppressed recombination within the introgressed rye chromosomal segment. We conclude that the initial effectiveness of 1AL.1RS was based on simultaneous introgression of two genetically linked resistance genes. Our results demonstrate the relevance of pathogen-based genetic approaches to disentangling complex resistance loci in wheat. We propose that identification and monitoring of avirulence gene diversity in pathogen populations become an integral part of introgression breeding to ensure effective and durable resistance in wheat.

Variations of subtelomeric tandem repeats and rDNA on chromosome 1RS arms in the genus Secale and 1BL.1RS translocations

BackgroundThe wheat-rye 1BL.1RS translocations have played an important role in common wheat breeding programs. Subtelomeric tandem repeats have been often used to investigate polymorphisms of 1RS arms, but further research about their organizations on the 1RS chromosome is needed.Results162 1RS arms from a wild rye species (Secale strictum) and six cultivated rye accessions (Secale cereale L.) (81 plants), 102 1BL.1RS and one 1AL.1RS translocations were investigated using oligo probes Oligo-TaiI, Oligo-pSc119.2–1, Oligo-pTa71A-2, Oligo-pSc200 and Oligo-pSc250, which were derived from tandem repeats TaiI, pSc119.2, pTa71, pSc200 and pSc250, respectively. The variations of 1RS arms were revealed by signal intensity of probes Oligo-pSc119.2–1, Oligo-pTa71A-2, Oligo-pSc200 and Oligo-pSc250. Proliferation of rDNA sequences on the 1RS chromosomes was observed. According to the presence of probe signals, 34, 127 and 144 of the 162 1RS arms contained TaiI, pSc200 and pSc250, respectively, and all of them contained pSc119.2 and pTa71. Most of the 1RS arms in rye contained three kinds of subtelomeric tandem repeats, the combination of pSc119.2, pSc200 and pSc250 was most common, and only eight of them contained TaiI, pSc119.2, pSc200 and pSc250. All of the 1RS arms in 1BL.1RS and 1AL.1RS translocations contained pSc119.2, pTa71, pSc200 and pSc250, but the presence of the TaiI family was not observed.ConclusionNew organizations of subtelomeric tandem repeats on 1RS were found, and they reflected new genetic variations of 1RS arms. These 1RS arms might contain abundant allelic diversity for agricultural traits. The narrow genetic base of 1RS arms in 1BL.1RS and 1AL.1RS translocations currently used in agriculture is seriously restricting their use in wheat breeding programs. This research has found new 1RS sources for the future restructuring of 1BL.1RS translocations. The allelic variations of these 1RS arms should be studied more intensely as they may enrich the genetic diversity of 1BL.1RS translocations.

Multiple resistance genes to leaf and stem rust in Brazilian wheat varieties ‘BRS194’ and ‘Toropi’

Leaf (Puccinia triticina; Pt) and stem (Puccinia graminis tritici; Pgt) rust are important constraints to wheat production. The leaf and stem rust resistance in the Brazilian wheat varieties ‘Toropi’ and ‘BRS194’ was evaluated using a ‘Toropi/BRS194’ doubled-haploid (DH) population. Parents evaluated at the seedling stage with Pt race MCJ-HN displayed infection type (IT) = ;1 for ‘BRS194’ and IT = 3 for ‘Toropi’. The DH progeny fit a 1R:1S ratio, indicating a single Lr gene in ‘BRS194’ was effective against race MCJ-HN. Adult plant testing with isolate 18-96-1 CCDS found that ‘BRS194’ displayed an IT = 3 and ‘Toropi’ IT = 1−, with segregating progeny consistent for multigenic adult plant resistance in ‘Toropi’. The parents and DH progeny were screened for the 1BL.1RS translocation (Sr31) with marker PE061, with ‘Toropi’ negative and ‘BRS194’ positive for the presence of Sr31. ‘BRS194’ was also tested against Pgt races MCCF, QTHJ, RHTS, RTHJ, TMRT, TPMK, and TTKSK at the seedling stage. BRS194 was resistant to all Pgt races, and an IT = 0 to TTKSK suggested the presence of Sr36. The presence of Sr36 in ‘BRS194’ was supported by the molecular marker STM773-2 (+) and ‘Arthur 71’ (Sr36 carrier) in its pedigree. Most resistant lines carried the Sr36-associated allele of STM773-2, while a few did not, indicating the presence of a second gene conferring resistance to TTKSK. Seedling resistance to Pgt in ‘Toropi’ was effective against races RHTS, MCCF, QTHJ, and RTHJ, postulated to be Sr9e. The variety ‘BRS194’ has effective rust-resistance genes that can be used in wheat-breeding programmes.

DIVERSITY OF WIDE HYBRIDIZATION DERIVATIVES OF WINTER WHEAT FOR RESISTANCE TO DISEASES AND OTHER ALIEN CHARACTERS

Introduction. The global climate change conduces spreading of main diseases of winter bread wheat (Triticum aestivum L.) and increases the yield losses caused by both these diseases and drought. Preventing the devastating impact of these factors on the yield depends on development of donors carrying the resistance genes. Aim. The diversity of new introgression wheat lines derived from complex interspecies crosses was evaluated for resistance to widespread diseases, drought and other agricultural traits. Methods. The trial was conducted consecutively during two vegetative periods (2018-2019 and 2019-2020) on the black earth area under the arid system in a control nursery design. Genetic material includes seventy-eight introgression wheat lines of different origin with two check cultivars for the arid climate zone of Ukraine. The data on nine agronomic (quantitative scores) and five plant pathological (point scores) traits were collected and subjected to both variance and correlation analysis to comprehend the contribution of the factors towards general diversity and connections between the characters. Results. Most lines were resistant to rust species due to the successful introgression of alien Lr, Yr and Sr genes from all sources involved in hybridization. High long-term resistance to stem rust was observed mainly among the derivatives of the collection sample H74/90-245 from Bulgaria, whose genetic background was favorable for generating a positive effect of 1BL.1RS translocation on both productive and adaptive traits in southern Ukraine and the ability to combine with other resistance genes. The yield traits did not correlate with the resistance to diseases except stem rust (Rsp = 0.34**) and Septoria blight (Rsp = −0.23*). Resistance to stem rust correlated with the grain and protein yield, test weight and flour density, which may be due to the presence of translocation 1BL.1RS. Negative correlation was observed between quality traits and grain yield, but quality traits mainly positively correlated with each other. The plant height had the highest contribution to grain yield followed by volume of 1000 kernels and WTK. Conclusions. The introgression lines were found to be diverse and potential for use in the wheat improvement programs for resistance to the diseases or drought in Southern Ukraine.

Triticum aestivum L. grain formation depending on the conditions of the year when crossing varieties with 1AL.1RS and 1BL.1RS translocations

The paper reveals the results of study on the parent components of soft winter wheat selection of the V.M. Remeslo Myronivka Institute of Wheat of the National Academy of Sciences of Ukraine and the Institute of Plant Physiology and Genetics of the National Academy of Sciences of Ukraine. The fndings demonstrate dependence of grain formation in the frst generation of interspecifc hybrids of soft winter wheat on the environmental factors and on wheatrye translocations 1AL.1RS and 1BL.1RS in the parental forms. The results of the analysis of variance show that the efciency of crossing and the percentage of grain formation signifcantly in the feld depended on the interaction of factors (47.7 %, p ≤ 0.05), on weather conditions (30.4 %) and the variety genotype (21.5 %) and did not depend signifcantly (0.4 %) on unaccounted factors (coincidence of flowering dates of the components involved in hybridization). In the group of crosses 1BL.1RS / 1BL.1RS, the average percentage of grain formation was the highest for three years (2016– 2018) and did not differ signifcantly – 50.1 %; 55.5 % and 49.8 %. The maximum average indicators for the research years (48.3 %) and under favorable weather conditions of 2017 (68.3 %) were obtained using the crosses of the variety of Svitanok myronivskyi 1BL.1RS as a parent form, and the minimum (37.1 % and 45.2 %, respectively) – using the variety of Kalynova 1BL.1RS. The results of the study show that hybrid combinations of Svitanok myronivskyi / Kalynova (56.1 %), Lehenda myronivska / Kalynova (54.6 %), Zolotokolosa / Svitanok myronivskyi (53.3 %), Lehenda myronivska / Ekspromt (52.4 %), Kolumbia / Zolotokolosa (48.1 %), Svitanok myronivskyi / Lehenda myronivska (47.6%) and Svitanok myronivskyi / Zolotokolosa (46.4 %) were the best in terms of the average percentage of grains formation for the research years. Key words: soft winter wheat, wheat-rye translocations, grain formation, weather conditions, genotype.