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The environmental adaptation of eudicots is the most reasonable explanation for why they compose the largest clade of modern plants (70% of angiosperms), which indicates that the basal eudicots would be valuable and helpful to study their survival and ability to thrive throughout evolutionary processes. Here, we detected two whole-genome duplication (WGD) events in the high-quality assembled Akebia trifoliata genome (652.73 Mb) with 24 138 protein-coding genes based on the evidence of intragenomic and intergenomic collinearity, synonymous substitution rate (K

A major and stable QTL cQSGR.sau.3D, which can explain 33.25% of the phenotypic variation in SGR, was mapped and validated, and cQSGR.sau.3D was found to be independent of GI. In this study, a recombinant inbred line (RIL) population containing 304 lines derived from the cross of Chuan-nong17 (CN17) and Chuan-nong11 (CN11) was genotyped using the Wheat55K single-nucleotide polymorphism array. A high-density genetic map consisting of 8329 markers spanning 4131.54 cM and distributed across 21 wheat chromosomes was constructed. QTLs for whole spike germination rate (SGR) were identified in multiple years. Six and fourteen QTLs were identified using the Inclusive Composite Interval Mapping-Biparental Populations and Multi-Environment Trial methods, respectively. A total of 106 digenic epistatic QTLs were also detected in this study. One of the additive QTLs, cQSGR.sau.3D, which was mapped in the region from 3.5 to 4.5 cM from linkage group 3D-2 on chromosome 3D, can explain 33.25% of the phenotypic variation in SGR and be considered a major and stable QTL for SGR. This QTL was independent of the seeds' germination traits, such as germination index. One Kompetitive Allele-Specific PCR (KASP) marker, KASP-AX-110772653, which is tightly linked to cQSGR.sau.3D, was developed. The genetic effect of cQSGR.sau.3D on SGR in the RIL and natural populations was successfully confirmed. Furthermore, within the interval in which cQSGR.sau.3D is located in Chinese Spring reference genomes, thirty-seven genes were found. cQSGR.sau.3D may provide new resources for pre-harvest sprouting resistance breeding of wheat in the future.

Stripe rust (caused by Puccinia striiformis f. sp. tritici) is one of the most severe diseases for wheat production. An important method to improve the stripe rust resistance of wheat is to introduce resistance genes from related species into the wheat genome. The 1RS.1BL wheat–rye translocation from Petkus rye has contributed substantially to wheat resistance breeding worldwide. However, given the breakdown of the stripe rust resistance gene Yr9 in 1RS, its importance for wheat improvement has decreased. In this study, we developed 166 new primary 1RS.1BL translocation lines by crossing rye varieties Weining, Baili, and Aigan with several wheat cultivars. Cytogenetic and molecular analyses indicated that all of these lines contained a pair of intact 1RS.1BL translocation chromosomes. The stripe rust resistance of these translocation lines and their wheat parents was evaluated in southwestern China during the severe stripe rust epidemics in 2015 and 2021. The results showed diverse effects of the 1RS.1BL translocations from different rye cultivars on resistance to stripe rust. The highest genetic diversity was observed in 1RS.1BL translocations derived from diverse rye varieties but in the same wheat background. The development of diverse 1RS.1BL translocation lines offers ample opportunities to introduce new variations into wheat for improving stripe rust resistance. Finally, 71 new translocation lines, including nine developed from the cross of MY11 × Aigan, four from MY11 × Baili, 40 from MY11 × Weining, 14 from A42912 × Baili, and four from A42912 × Weining. These lines showed consistent resistance to stripe rust in fields under frequent changes of the pathogen races and could be useful genetic stocks for breeding wheat cultivars with resistance to stripe rust.

Wheat-rye 1RS·1BL translocations from ‘Petkus’ rye have contributed substantially to wheat production worldwide with their great disease resistance and yield traits. However, the resistance genes on the 1RS chromosomes have completely lost their resistance to newly emerged pathogens. Rye could widen the variation of 1RS as a naturally cross-pollinated related species of wheat. In this study, we developed three new 1RS·1BL translocation lines by crossing rye inbred line BL1, selected from Chinese landrace rye Baili, with wheat cultivar Mianyang11. These three new translocation lines exhibited high resistance to the most virulent and frequently occurring stripe rust pathotypes and showed high resistance in the field, where stripe rust outbreaks have been most severe in China. One new gene for stripe rust resistance, located on 1RS of the new translocation lines, is tentatively named YrRt1054. YrRt1054 confers resistance to Puccinia striiformis f. sp. tritici pathotypes that are virulent toward Yr9 and YrCn17. This new resistance gene, YrRt1054, is available for wheat improvement programs. The present study indicated that rye cultivars may carry additional untapped variation as potential sources of resistance.

This study identified QTLs associated with the functional stay green trait by a high-density genetic map. Two large effect QTLs, QSg.sau-2B.1 and QSg.sau-6A.2, were identified in multiple years and one of them was successfully validated. The functional stay green phenotype enables wheat to acclimate to stressful environments and prolongs the effectiveness of photosynthesis during the end-of-crop season. Despite the fact that stay green mutants in wheat have been reported, our knowledge of loci for the functional stay green trait remains limited. In this study, an RIL population containing 371 lines genotyped using the Wheat55K SNP array was used to map QTLs controlling the functional stay green trait in multiple years. In total, 21 and 19 QTLs were mapped using the BIP or MET modules of the ICIM method, respectively. Among them, two QTLs, QSg.sau-2B.1 and QSg.sau-6A.2, were considered large effect QTLs for the stay green trait and explained 11.43% and 15.27% of phenotypic variation on average, respectively. Two KASP markers were developed and tightly linked to QSg.sau-2B.1 and QSg.sau-6A.2, respectively, and the genetic effects of different genotypes in the RIL population were successfully confirmed. QSg.sau-2B.1 was also validated by linked KASP marker in different genetic backgrounds. QSg.sau-2B.1 and QSg.sau-6A.2 may influence heredity of the stay green trait and also exhibited a positive effect on the grain filling content. In the interval where QSg.sau-2B.1 and QSg.sau-6A.2 were located on the Chinese Spring and T. turgidum ssp. dicoccoides reference genomes, several genes associated with the leaf senescence process were identified. Altogether, our results identified two QTLs associated with the functional stay green trait and will be useful for the fine mapping and cloning of genes for stay green in the future.

Genetic diversity is usually regarded as an important role for understanding the origin, evolution and environmental adaptation of species. A total of 174 living collections of Akebia trifoliata and 72 high-polymorphism-potential (HPP) simple sequence repeat (SSR) markers were employed to systematically explore the diversity and structure of this species. The average number of alleles (Na), Shannon's information index (I), number of effective alleles (Ne), observed heterozygosity (Ho), expected heterozygosity (He) and polymorphism information content (PIC) values were 9.01, 1.64, 4.98, 0.56, 0.72 and 0.69, respectively, and the linkage disequilibrium (LD) locus pairs percentage was on 1.17%. The PIC value of AK78 was the highest (0.92), while that of AK53 was the lowest (0.21). Sixty of 72 loci exhibited high polymorphism, while only one exhibited low polymorphism. In addition, the average PIC of chromosomes varied from 0.56 to 0.79. The genetic diversity of the SCB population was the highest, while that of NQH was the lowest. Further analysis of SCB suggested that JSJ-MJ, in the main part of the Heng Duan Mountain zone, had the highest genetic diversity and could be the origin centre of A. trifoliata. The main migration route of A. trifoliata could have been latitudinally from western to eastern China along the Yangtze River. Structure, cluster and principal coordinate analyses yielded similar results, revealing that the 6 populations could be divided into 2 groups or clusters. The geographic origin of several unknown accessions, such as Alc-166, Alc-171, Alc-172 and Alc-174, was revealed by cluster analysis. Overall, the results suggested that the living collections of A. trifoliata had high genetic diversity, good representativeness, and low duplication, which will benefit A. trifoliata germplasm collection, preservation, and breeding applications.

As the largest clade of modern plants, flower plants have evolved a wide variety of flowers and fruits. MADS-box genes play key roles in regulating plant morphogenesis, while basal eudicots have an evolutionarily important position of acting as an evolutionary bridge between basal angiosperms and core eudicots.

WRKY transcription factors have been found in most plants and play an important role in regulating organ growth and disease response. Outlining the profile of

Secale cereale is used as a source of genes for disease resistance in wheat cultivation. In this study, a homozygous translocation line (RT14-245) that originated from a cross between a commercial wheat cultivar (Mianyang 11) and a local Chinese variety of rye (Baili) was developed. Multicolor fluorescence in situ hybridization and PCR analysis demonstrated that the translocation chromosome was 7BS.7RL. Resistance analysis showed that RT14-245 was resistant to prevalent pathotypes of stripe rust and powdery mildew. RT14-245 also exhibited high resistance to Fusarium head blight, which was similar to the resistance exhibited by the wheat cultivar Sumai 3. The results indicated that RT14-245 simultaneously exhibited high levels of resistance against stripe rust, powdery mildew, and Fusarium head blight. These results indicate that chromosome arm 7RL in the translocation line RT14-245 is an excellent new resource for wheat breeding programs.

Wheat powdery mildew, caused by the obligate parasite Blumeria graminis f. sp. tritici, severely reduces wheat yields. Identifying durable and effective genes against wheat powdery mildew and further transferring them into wheat cultivars is important for finally controlling this disease in wheat production. Pm40 has been widely used in wheat breeding programs in Southwest China due to the spectrum and potentially durable resistance to powdery mildew. In the present study, a resistance test demonstrated that Pm40 is still effective against the Bgt race E20. We identified and cloned the TraesCS7B01G164000 with a total length of 4883 bp, including three exons and two introns, and encoded a protein carrying the CC-NBS-NBS-LRR domain in the Pm40-linked region flanked by two EST markers, BF478514 and BF291338, by integrating analysis of gene annotation in wheat reference genome and both sequence and expression difference in available transcriptome data. Two missense mutations were detected at positions 68 and 83 in the CC domain. The results of both cosegregation linkage analysis and qRT-PCR also suggested that TraesCS7B01G164000 was a potential candidate gene of Pm40. This study allowed us to move toward the final successfully clone and apply Pm40 in wheat resistance improvement by gene engineering.

Akebia trifoliata, a member of the family Lardizabalaceae, has high exploitation potential for multiple economic purposes, so genetic improvements to meet requirements for commercial demand are needed. However, this progress is largely impeded by a lack of effective selection markers. In this study, we obtained 271.49 Gb of clean transcriptomic data from 12 samples (three tissues at four developmental stages) of A. trifoliata fruit. We identified 175,604, 194,370, and 207,906 SSRs from the de novo assembled 416,363, 463,756, and 491,680 unigene sequences obtained from the flesh, seed, and rind tissues, respectively. The profile and proportion of SSR motifs expressed in each fruit tissue and developmental stage were remarkably similar, but many trinucleotide repeats had differential expression levels among different tissues or at different developmental stages. In addition, we successfully designed 16,869 functional EST-SSR primers according to the annotated unigenes. Finally, 94 and 72 primer pairs out of 100 randomly selected primer pairs produced clear bands and polymorphic bands, respectively. These results were also used to elucidate the expression profiles of different tissues at various stages. Additionally, we provided a set of effective, polymorphic, and reliable EST-SSR markers sufficient for accelerating the discovery of metabolic and pathway-specific functional genes for genetic improvement and increased commercial productivity.

This study mapped QTLs associated with kernel-related traits by high-density genetic map. Five new major and stable QTLs for KL, KDR, SN, and KWPS were mapped in multiple environments. In the present study, a recombinant inbred line population including 371 lines derived from the cross of Chuannong18 and T1208 was genotyped using the Wheat55K single nucleotide polymorphism array. A novel high-density genetic map consisting of 11,583 markers spanning 4192.62 cM and distributed across 21 wheat chromosomes was constructed. QTLs for important kernel-related traits were mapped in multiple environments. A total of 96 and 151 QTLs were mapped by using the ICIM method and the MET method, respectively. And a total of 114 digenic epistatic QTLs were also detected across 21 chromosomes, and the epistatic effects of each trait were analyzed. BLAST analysis showed that 23 QTLs for different kernel-related traits were first time mapped and five of them were major and stable QTLs for kernel diameter ratio (121.34-126.83 cM on 4BS), spike number per square meter (71.32-73.84 cM on 2DS), kernel weight per spike (71.32-75.26 cM on 2DS), and kernel length (16.78-31.64 cM on 6A and 51.63-58.40 cM on 3D), respectively. Fifteen QTL clusters that contained 58 QTLs were also detected, and all most stable QTLs were contained in these QTL clusters. Significant correlations between different traits were detected and discussed. These results lay the foundation for fine mapping and cloning of the gene(s) underlying the stable QTLs detected in this study.

Rye is a valuable food and forage crop, an important genetic resource for wheat and triticale improvement and an indispensable material for efficient comparative genomic studies in grasses. Here, we sequenced the genome of Weining rye, an elite Chinese rye variety. The assembled contigs (7.74 Gb) accounted for 98.47% of the estimated genome size (7.86 Gb), with 93.67% of the contigs (7.25 Gb) assigned to seven chromosomes. Repetitive elements constituted 90.31% of the assembled genome. Compared to previously sequenced Triticeae genomes, Daniela, Sumaya and Sumana retrotransposons showed strong expansion in rye. Further analyses of the Weining assembly shed new light on genome-wide gene duplications and their impact on starch biosynthesis genes, physical organization of complex prolamin loci, gene expression features underlying early heading trait and putative domestication-associated chromosomal regions and loci in rye. This genome sequence promises to accelerate genomic and breeding studies in rye and related cereal crops., A high-quality genome assembly of Weining rye sheds new light on gene duplications and their effects on starch biosynthesis genes, gene expression features underlying early heading trait and putative domestication-associated chromosomal regions.

Complex chromosome rearrangements (CCRs) are defined as structural abnormalities involving more than two chromosome breaks, coupled with exchanges of chromosomal segments. Information on CCRs in plants is limited. In the present study, a plant (26-4) harboring translocation chromosomes 1RS.1BL and 4RS.4DL was selected from a double monosomic (1R and 4R) addition line, which was derived from the hybrid between wheat cultivar MY11 and a Chinese local rye variety. The genome of the plant with double alien translocation chromosomes in the monosomic form showed more instability than that harboring a single translocation. The CCRs involving chromosomes 1RS.1BL and 3B, which were generated de novo in this plant, showed double monosomic translocation chromosomes. A new CCR line with balanced reciprocal translocations 1RS.3BL and 3BS.1BL was developed, which presented normal morphological traits of wheat and underwent rapid growth in the field. A new 1RS.1BL translocation line was also selected from the progeny of plant 26-4. The CCRs and simple 1RS.1BL translocation lines showed significant improvement in grain yield, number of spikes per square meter, kernel number per spike, and resistance to stripe rust and powdery mildew. The CCR line exhibited better agronomic traits and adult plant resistance in the field than its sister line, which harbored a simple 1RS.1BL translocation. The CCRs are remarkable genetic resources for crop improvement.

Non-denaturing fluorescence in situ hybridization (ND-FISH) has been used to distinguish wheat chromosomes and to detect alien chromosomes in the wheat genome. In this study, five different oligonucleotide probes were used with ND-FISH to examine 21 wheat cultivars and lines. These oligonucleotide probes distinguished 42 wheat chromosomes and also detected rye chromatin in the wheat genome. Moreover, the signal patterns of the oligonucleotide probes Oligo-pTa535-1 and Oligo-pSc119.2-1 showed high polymorphism in the wheat chromosomes. A total of 17.6% of the A group chromosomes, 25.9% of the B group chromosomes and 8.9% of the D group chromosomes showed obvious mutations when they were compared to the standard ND-FISH signal patterns, and most of them were Oligo-pSc119.2-1 mutants. The results suggested that these polymorphisms could be induced by the crossing of wheat cultivars. The results provided more information for the further application of oligonucleotide probes and ND-FISH.

This study mapped QTLs associated with kernel-related traits by high-density genetic map. Five new major and stable QTLs for KL, KDR, SN, and KWPS were mapped in multiple environments. In the present study, a recombinant inbred line population including 371 lines derived from the cross of Chuannong18 and T1208 was genotyped using the Wheat55K single nucleotide polymorphism array. A novel high-density genetic map consisting of 11,583 markers spanning 4192.62 cM and distributed across 21 wheat chromosomes was constructed. QTLs for important kernel-related traits were mapped in multiple environments. A total of 96 and 151 QTLs were mapped by using the ICIM method and the MET method, respectively. And a total of 114 digenic epistatic QTLs were also detected across 21 chromosomes, and the epistatic effects of each trait were analyzed. BLAST analysis showed that 23 QTLs for different kernel-related traits were first time mapped and five of them were major and stable QTLs for kernel diameter ratio (121.34–126.83 cM on 4BS), spike number per square meter (71.32–73.84 cM on 2DS), kernel weight per spike (71.32–75.26 cM on 2DS), and kernel length (16.78–31.64 cM on 6A and 51.63–58.40 cM on 3D), respectively. Fifteen QTL clusters that contained 58 QTLs were also detected, and all most stable QTLs were contained in these QTL clusters. Significant correlations between different traits were detected and discussed. These results lay the foundation for fine mapping and cloning of the gene(s) underlying the stable QTLs detected in this study.

Yr41 is an all-stage resistance gene against wheat stripe rust. Previous greenhouse tests showed that Yr41 had strong resistance to races CYR31, CYR32, SY11–4, V26, and so on. To evaluate the contribution of Yr41 in practical wheat production, three F2 populations derived from disease-resistant parents, AIM5 and AIM6, which carry Yr41, and a susceptible parent L661, which lacks Yr41 (i.e., AIM5/L661, AIM6/L661, and L661/AIM5) were employed to investigate resistance responses and yield components under field conditions. Therefore, the molecular marker BE446068, which is closely linked to Yr41, within 0.19 cM, was also employed to identify the F2 plant genotypes. A χ2 test showed that infection type exhibited a significantly skewed distribution in the three genotypes of homogenous RR, heterogeneous Rr, and homogenous rr plants but not in the heterogeneous Rr plants derived from AIM5/L661 at the P = 0.05 level, indicating that Yr41 was effective against stripe rust. Multiple comparison analysis of yield parameters among various genotypes showed that yield parameter TGW exhibited significant differences among the three genotypes of all cross combinations at the P = 0.05 level, and there was no obvious difference in PEP among them, which could be explained by the onset and development of stripe rust. Multiple comparison results suggested that Yr41 could protect yields by preventing decreases in yield parameters, especially TGW, with additive and partial dominant effects. Yr41 will play an important role in the improvement of wheat resistance to stripe rust and wheat production practices and provide a new strategy to evaluate disease resistance under field conditions.

Rye is one of the most important related species used for wheat genetic improvement and breeding programs. In the present study, five novel 1BL.1RS translocations were developed and characterized from crossing of the common wheat line A42912 and a Chinese rye “Baili”. Codominant PCR and MC-FISH determined that these five translocation lines harbored a pair of 1BL.1RS chromosomes. The MC-FISH results indicated that several accompanying mutations on the wheat chromosomes occurred during the chromosome translocation process. These five new 1BL.1RS translocation lines also exhibited high resistance to stripe rust and powdery mildew and showed significantly better yield traits in the field. The present study indicates that Baili rye may carry yet untapped and potentially important sources of resistance, which may be used for wheat genetic improvement. These five novel primary 1BL.1RS translocations are likely to find application in wheat genetic improvement programs.

Maximum tiller number and productive tiller number are important traits for wheat grain yield, but research involving the temporal expression of tiller number at different quantitative trait loci (QTL) levels is limited. In the present study, a population set of 371 recombined inbred lines derived from a cross between Chuan-Nong18 and T1208 was used to construct a high-density genetic map using a Wheat55K SNP Array and to perform dynamic QTL analysis of the tiller number at four growth stages. A high-density genetic map containing 11,583 SNP markers and 59 SSR markers that spanned 4,513.95 cM and was distributed across 21 wheat chromosomes was constructed. A total of 28 single environmental QTL were identified in the recombined inbred lines population, and among these, seven QTL were stable and used for multi-environmental and dynamic analysis. These QTL were mapped to chromosomes 2D, 4A, 4D, 5A, 5D, and 7D, respectively. Each QTL explained 1.63-21.22% of the observed phenotypic variation, with an additive effect from -20.51 to 11.59. Dynamic analysis showed that cqTN-2D.2 can be detected at four growth stages of tillering, explaining 4.92-17.16% of the observed phenotypic variations and spanning 13.71 Mb (AX-109283238-AX-110544009: 82189047-95895626) according to the physical location of the flanking markers. The effects of the stable QTL were validated in the recombined inbred lines population, and the beneficial alleles could be utilized in future marker-assisted selection. Several candidate genes for MTN and PTN were predicted. The results provide a better understanding of the QTL selectively expressing the control of tiller number and will facilitate future map-based cloning. 9.17% SNP markers showed best hits to the Chinese Spring contigs. It was indicated that Wheat55K Array was efficient and valid to construct a high-density wheat genetic map.

Falling number (FN) is an inner quality trait in wheat (Triticum aestivum L.) ultimately determining the end use of wheat kernels. In this 3-year study, 171 recombinant inbred lines derived from Chuannong17 (a 1BL/1RS tranlocation parent) × Mianyang11 were planted in the Sichuan Basin, a rainfed agricultural area in southwestern China. In this climate, we found that FN had significant differences between 1BL/1RS translocation lines and non-1BL/1RS translocation lines in two of the 3 years and the heavy fluctuation of rainfall and temperature resulted in decreasing FN in grain filling period. We used 191 simple sequence repeats markers to construct a genetic linkage map and then detected 11 additive effect FN quantitative trait loci (QTL) on chromosomes 2B, 3D, 4A, 4D, 6B and 7D, explaining 5.48–31.91% of the phenotypic variance. The FN QTL on chromosomes 4A, 4D and 6B were major or stable and detected at least in 2 years, whereas the Qfn.sicau-3D.1 in 2015 year explained the maximum phenotypic variation (about 31.91%). Furthermore, FN QTLs additive and epistatic effects as well as their interactions with environment were estimated by a mixed linear model approach. We found that the additive effect QTLs had no significant additive × environment interaction, while the paired QTLs had significant additive × additive epistatic effects however none had a significant additive × additive epistasis × environment interaction effect, excluding the paired QTLs Qfn.sicau-3B/Qfn.sicau-5B.

Rye has been used worldwide as a source for the genetic improvement of wheat. In this study, two stable wheat-rye primary T1RS.1BL translocation lines were selected from the progeny of the crossing of the wheat cultivar Mianyang11-1 and a Chinese local rye variety, Weining. These two novel translocation lines were identified by molecular cytogenetic analysis. PCR results, multi-color fluorescence in situ hybridization (MC-FISH), and acid polyacrylamide gel electrophoresis (A-PAGE) indicated that both new translocation lines harbor a pair of T1RS.1BL translocation chromosomes, and have been named RT828-10 and RT828-11, respectively. The cytogenetic results also indicated that the pSc119.2 signals of 5AL were absent in both lines along with the pSc119.2 signals of 4AL of RT828-11. When inoculated with different stripe rust and powdery mildew isolates, both lines expressed high resistance to Puccinia striiformis f. sp. tritici and Blumeria graminis f. sp. tritici pathotypes, which are prevalent in China and are virulent on Yr9 and Pm8. The line RT828-11 also exhibited excellent agronomic traits in the field. The present study indicates that this rye variety may carry untapped variations that could potentially be used for wheat improvement.

Spike formation rate (SR), which is based on maximum tiller number per unit area and spike number per unit area, is an important yield-related trait in wheat. Increasing the spike formation rate reduces growth competition and wastage of photosynthate from ineffective tillers. Unfortunately, research studies involving quantitative trait locus (QTL) mapping for wheat spike formation rate are limited. In the present study, a set of 371 recombinant inbreed line (RIL) population, which were derived from 1BL/LRS wheat-rye translocation lines CN18 and T1208, was analysed by simple sequence repeat (SSR) markers. Genetic analysis showed that a stable and major QTL (QSR.sicau-4D) for spike formation rate was localized to chromosome 4D and explained 18.24% and 24.48% of the observed phenotypic variance in 2015 and 2016, respectively. This QTL was closely linked to SSR marker Xcfd23, and the genetic distance between the flank markers was 3.28 cM. Furthermore, QSR.sicau-4D might be a novel pleiotropic QTL, which also controlled maximum tiller number per unit area (QMTN.sicau-4D) and tiller number during pre-winter per unit area (QTNW.sicau-4D). The marker Xcfd23 associated with SR may be utilized in marker-assisted selection in wheat breeding.

The 1BL.1RS wheat-rye translocation contained in the Russian cultivar Aurora has been the most widespread alien translocation in wheat-breeding programs all over the world. However, following the prevalence of new biotypes of the pathogens, disease-resistance genes in this translocation chromosome have been overcome and consequently they have been eliminated in modern wheat-breeding programs. In this paper, we report on 12 new primary 1BL.1RS translocation lines derived from the crosses of a Chinese high yield wheat cv. Mianyang 11 with three rye cultivars collected from China. GISH, C-banding and PCR techniques using the specific primers for 1BS, 1RS and centromeres of wheat and rye were applied to identify the constitution of chromosomes. The results confirmed that all 1BL.1RS chromosomes in the 12 primary translocation lines contained integrated 1RS chromosome arms. In the resistance analysis using five kinds of Pst pathotypes, the 12 primary translocation lines showed diversity resistance to stripe rust, which contained at least five different new genes (alleles), significantly different from the Yr9 gene coming from Russian wheat cultivar Aurora. The results indicated that the chromosome arm 1RS in the rye population carries abundant yet untapped genes (alleles) for resistance to wheat stripe rust, which would originate from the neutral diversity in the natural population of rye. It is suggested that creating more primary translocation lines in genome modification will be extremely important to use the diversity of alien R-genes, which was generated by long-term neutral mutation and maintained in the population of alien species.

Increased chromosome instability was induced by a rye (Secale cereale L.) monosomic 2R chromosome into wheat (Triticum aestivum L.). Centromere breakage and telomere dysfunction result in high rates of chromosome aberrations, including breakages, fissions, fusions, deletions, and translocations. Plants with target traits were sequentially selected to produce a breeding population, from which 3 translocation lines with target traits have been selected. In these lines, wheat chromosomes 2A, 2B, and 7B recombined with segments of the rye chromosome arm 2RL. This was detected by FISH analysis using repeat sequences pSc119.2, pAs1 and genomic DNA of rye together as probes. The translocation chromosomes in these lines were named as 2ASMR, 2BSMR, and 7BSMR. The small segments that were transferred into wheat consisted of pSc119.2 repeats and other chromatin regions that conferred resistance to stripe rust and expressed target traits. These translocation lines were highly resistant to stripe rust, and expressed several typical traits that were associated with chromosome arm 2RL, which are better than those of its wheat parent, disomic addition, and substitution lines that show agronomic characteristics. The integration of molecular methods and conventional techniques to improve wheat breeding schemes are discussed.

Secale cereale L. has been used worldwide as a source of genes for agronomic and resistance improvement. In this study, a stable wheat-rye substitution line and 3 primary 1RS.1BL translocation lines were selected from the progeny of the crossing of the Chinese local rye Aigan variety and wheat cultivar Mianyang11. The substitution and translocation lines were identified by molecular cytogenetic analysis. PCR results, fluorescence in situ hybridization and acid polyacrylamide gel electrophoresis indicated that there were a pair of 1R chromosomes in the substitution line which have been named RS1200-3, and a pair of 1RS.1BL translocation chromosomes in the other 3 translocation lines, which have been named RT1163-4, RT1217-1, and RT1249. When inoculated with stripe rust isolates, these 4 lines expressed high resistance to several Puccinia striiformis f. sp Tritici pathotypes that are virulent on Yr9. Moreover, the different response pattern of resistance among them suggested that the diversity of resistance genes for wheat stripe rust exists in the rye. These 4 lines also showed better agronomic performances than their wheat parent. The GS indices also showed the genetic diversity of the 1RS which derived from same rye variety. The present study indicates that rye cultivars may carry untapped variations that could potentially be used for wheat improvement.

Many studies have been conducted to determine the relative effects of the 1BL.1RS translocation on various traits in wheat. The effects of different wheat (Triticum aestivum L.) genetic backgrounds and rye (Secale cereale L.) sources have been addressed as major factors for inconsistent agronomic performance and end-use-quality traits of 1BL.1RS translocation wheats. However, all these studies were accomplished by using 1BL.1RS translocations with impure wheat genetic bases and narrow rye origins. The objective of this study was to test the genetic effects of centric fusion translocations by using primary 1BL.1RS lines derived from various pure wheat lines and rye sources. Twenty-one primary 1BL.1RS translocation lines were created from crosses between two pure wheat lines and three Chinese local rye varieties. These translocation lines and their wheat parents were then evaluated in southwestern China. The results provide direct evidence of the diverse effects of the different wheat parents and rye sources, taking part in 1BL.1RS translocations, on resistance to diseases, agronomic performance, and end-use quality traits. The highest amount of genetic diversity was observed in 1BL.1RS translocations derived from the same wheat lines and diverse rye varieties. The results suggest that the genetic diversity of 1BL.1RS translocation lines may originate from the different wheat genetic backgrounds, from different rye sources, from their interaction, and from the translocation itself. Creation of diverse 1BL.1RS translocations offers ample possibilities to introduce more variation into wheat for improved performance.