Tianheng Ren

The flag leaf serves as the primary photosynthetic organ in wheat, and its size is significantly correlated with wheat yield. The mapping of QTLs associate

Stripe rust and powdery mildew are serious diseases that significantly reduce wheat yield. Distant hybridization between wheat and its related species to develop disease-resistant translocation lines is an effective method for enhancing wheat's disease resistance. However, many newly developed disease-resistant wheat-related species translocation lines are difficult to use in wheat breeding because of their poor agronomic traits. Therefore, developing translocation lines that are resistant to diseases and have good agronomic traits is key for further use in wheat breeding programs. In this study, five novel T2AS.2RL translocation lines were developed from a cross between a high-yield wheat cultivar, CN25, and a Chinese rye landrace, Qinling. The results of cytogenetics and molecular analyses indicated that all five lines contained a pair of T2AS.2RL translocation chromosomes. These T2AS.2RL lines were highly resistant to stripe rust and powdery mildew. Genetic analysis indicated that resistance to stripe rust and powdery mildew was conferred by the 2RL chromosome arms derived from Qinling. In addition, compared with their high-yielding wheat parent CN25, these translocation lines presented good agronomic traits and no significant difference in yield. These results indicate that these new T2AS.2RL lines have great potential for use in future wheat breeding programs.

Fusarium head blight (FHB) is a serious disease that severely decreases the yield and quality of wheat. Planting wheat cultivars with FHB resistance is one of the most effective ways to control FHB epidemics. Introducing chromosome fragments from wheat-related species with FHB resistance into the wheat genome through chromosome translocation is an important way to improve wheat FHB resistance. In this study, 178 new wheat–rye ( Secale cereale) T1RS.1BL translocation lines were developed from the crosses of common wheat and three Chinese rye landraces: Weining, Baili, and Aigan. The wheat parents Mianyang11 (MY11) and A42912 were susceptible to FHB, and the percentage of diseased spikelets (PDS) values of MY11 and A42912 were 63.41 and 50.52% at 30 days postinoculation (DPI), respectively. The PDSs of the translocation lines developed from the MY11 × Aigan, MY11 × Baili, MY11 × Weining, A42912 × Baili, and A42912 × Weining crosses ranged from 14.32 to 37.68%, 20.21 to 35.38%, 13.58 to 45.28%, 12.93 to 32.87%, and 20.18 to 31.14% at 30 DPI, respectively. The increasing PDS per day in the translocation lines was lower than those in the wheat parents from 20 to 30 DPI. All the results showed that the 1RS translocations of the three Chinese rye strains effectively improved FHB resistance when introduced into the wheat genome. The FHB-resistant germplasm resources evaluated in this study are important materials for future FHB-resistant wheat breeding.

Key message QTLs for seven different quality traits were mapped. Six QTLs were considered stable and major QTLs, and the genetic effects of the QTLs were validated. Abstract Wheat grain quality traits are the key factors for economic value and are largely influenced by genetics and the environment. In this study, a genetic linkage map consisting of 8329 markers spanning 4131.54 cM was constructed using the Wheat55K SNP Array by genotyping a recombinant inbred line population of 304 lines. The quantitative trait loci (QTLs) for the swelling index of glutenin, SDS sedimentation volume (SDSS), wet gluten content, grain protein content, gluten index, grain starch content, and falling number were mapped for multiple years of experiments using the ICIM-BIP, ICIM-MET, and ICIM-EPI methods, respectively. A total of 92 QTLs, 194 cQTLs, and 117 pairs of eQTLs were mapped. Six QTLs, which were QGPC.sau-4A.1, QWGC.sau-4A, QSDSS.sau-1A.1, QGI.sau-1A, QFN.sau-4D, and QSIG.sau-1A, were considered major and stable QTLs. BLAST results showed that except QFN.sau-4D, the other 5 QTLs were new. Eight QTL clusters that contained 19 QTLs were also detected, and all the major and stable QTLs were located in these QTL clusters. Kompetitive allele-specific PCR markers closely linked to the six QTLs were designed. The genetic effects of the major and stable QTLs were successfully confirmed in different populations. These results provide new resources for breeding of high-quality wheat in the future.

Introduction: Rye (Secale cereale L.) played a very important role in wheat genetic improvement and forage production worldwide. However, since rye is a kind of cross-pollinated plant, high levels of genetic heterozygosity and heterogeneity existed in the genome. Genome-wide variation in repeat sequences is one of the most important reasons for chromosome evolution in rye. High-precision cytological identification can effectively identify the heterochromatin or repeat sequence variations in the rye genome, and the relationship between different rye varieties can be identified while obtaining the FISH-karyotype of different rye varieties. The evolution of rye chromosomes can be analyzed by the variation degree of different probes on rye chromosomes.Methods: All materials were identified by non-denaturing fluorescence in situ hybridization (ND-FISH). Five probes, (AAC)₆, Oligo-pSc119.2-1, Oligo-pTa71A-2, Oligo-pSc200, and Oligo-pSc250 were used to identify rye chromosomes.Results: 15 rye varieties including S. cereale (cultivated rye and weedy rye), S. strictum (wild rye), S. sylvestre (wild rye), and S. vavilovii (wild rye) were examined by five oligonucleotides probes. 92 signal sites and 2074 signal patterns were observed, suggesting that high polymorphisms exist in the different rye genomes. The karyotypes of 15 rye varieties were obtained, the frequency of different signal types at each signal site was calculated and the model diagrams of probes (AAC)₆, Oligo-pSc119.2-1, Oligo-pTa71A-2, Oligo-pSc200 + Oligo-pSc250 were drawn. The results showed that the rate of variation of different chromosomes of rye was not consistent. 1R, 6R, and 7R have higher variation and genetic diversity, while 2R and 3R have lower variation and are more conserved relative to other chromosomes. The results also indicated that S. sylvestre has a far genetic distance from other rye species, and S. vavilovii might be one of the ancestors of Chinese rye varieties.Discussion: Results from this study confirmed rapid chromosome change and high levels of chromosome diversity in rye.

Rye (Secale cereale L.) is the most widely used related species in wheat genetic breeding, and the introduction of its chromosome fragments into the wheat genome through distant hybridization is essential for enriching the genetic diversity of wheat. Rapid and accurate detection of rye chromatin in the wheat genome is important for distant hybridization. Simple sequence repeats (SSRs) are widely distributed in the genome, and SSRs of different species often exhibit species-specific characteristics. In this study, genome-wide SSRs in rye were identified, and their characteristics were outlined. A total of 997,027 SSRs were selected, with a density of 115.97 SSRs/Mb on average. There was no significant difference in the number of SSRs on each chromosome. The number of SSRs on 2R was the highest (15.29%), and the number of SSRs on 1R was the lowest (13.02%). The number of SSRs on each chromosome is significantly correlated with chromosome length. The types of SSR motifs were abundant, and each type of SSR was distributed on 7 chromosomes of rye. The numbers of mononucleotide simple sequence repeats (MNRs), dinucleotide simple sequence repeats (DNRs), and trinucleotide simple sequence repeats (TNRs) were the greatest, accounting for 46.90%, 18.37%, and 22.64% of the total number, respectively. Among the MNRs, the number of G/C repeats and the number of 10 bp motifs were the greatest, accounting for 26.24% and 31.32% of the MNRs, respectively. Based on the SSR sequences, a total of 657 pairs of primers were designed. The PCR results showed that 119 pairs of these primers were rye-specific and could effectively detect rye chromatin in the wheat genome. Moreover, 86 pairs of the primers could also detect one or more specific rye chromosomes. These results lay a foundation for both genomic evolution studies of rye and molecular breeding in wheat.

Stripe rust and powdery mildew are serious diseases that severely decrease the yield of wheat. Planting wheat cultivars with powdery mildew and stripe rust resistance genes is the most effective way to control these two diseases. Introducing disease resistance genes from related species into the wheat genome via chromosome translocation is an important way to improve wheat disease resistance. In this study, nine novel T1RS.1AL translocation lines were developed from the cross of wheat cultivar Chuannong25 (CN25) and a Chinese rye Qinling. The results of non-denaturing fluorescence in situ hybridization and PCR showed that all new lines were homozygous for the T1RS.1AL translocation. These new T1RS.1AL translocation lines exhibited strong resistance to stripe rust and powdery mildew. The cytogenetics results indicated that the resistance of the new lines was conferred by the 1RS chromosome arms, which came from Qinling rye. The genetic analysis indicated that there were new dominant resistance genes on the 1RS chromosome arm resistant to stripe rust and powdery mildew, and their resistance patterns were different from those of Yr9, Pm8, and Pm17 genes. In addition, the T1RS.1AL translocation lines generally exhibited better agronomic traits in the field relative to CN25. These T1RS.1AL translocations have great potential in wheat-breeding programs in the future.

Key message A major and stable QTL, QFn.sau-1B.2, which can explain 13.6% of the PVE in FN and has a positive effect on resistance in SGR, was mapped and validated. Abstract The falling number (FN) is considered one of the most important quality traits of wheat grain and is the most important quality evaluation index for wheat trade worldwide. The quantitative trait loci (QTLs) for FN were mapped in three years of experiments. 23, 30, and 58 QTLs were identified using the ICIM-BIP, ICIM-MET, and ICIM-EPI methods, respectively. Among them, seven QTLs were considered stable. QFn.sau-1B.2, which was mapped to the 1BL chromosome, can explain 13.6% of the phenotypic variation on average and is considered a major and stable QTL for FN. This QTL was mapped in a 1 cM interval and is flanked by the markers AX-110409346 and AX-108743901. Epistatic analysis indicated that QFN.sau-1B.2 has a strong influence on FN through both additive and epistatic effects. The Kompetitive Allele-Specific PCR marker KASP-AX-108743901, which is closely linked to QFn.sau-1B.2, was designed. The genetic effect of QFn.sau-1B.2 on FN was successfully confirmed in Chuannong18 × T1208 and CN17 × CN11 populations. Moreover, the results of the additive effects of favorable alleles for FN showed that the QTLs for FN had significant effects not only on FN but also on the resistance to spike germination. Within the interval of QFn.sau-1B.2, 147 high-confidence genes were found. According to the gene annotation and the transcriptome data, four genes might be associated with FN. QFn.sau-1B.2 may provide a new resource for the high-quality breeding of wheat in the future.

Akebia trifoliata is an economically important, self-incompatible fruit tree in the Lardizabalaceae family. Asexual propagation is the main strategy used to maintain excellent agronomic traits. However, the generation of adventitious roots during asexual propagation is very difficult. To study the important role of the WUSCHEL-related homeobox (WOX) transcription factor in adventitious root growth and development, we characterized this transcription factor family in the whole genome of A. trifoliata. A total of 10 AktWOXs were identified, with the following characteristics: length (657~11,328 bp), exon number (2~5), isoelectric point (5.65~9.03), amino acid number (176~361 AA) and molecular weight (20.500~40.173 kDa), and their corresponding expression sequence could also be detectable in the public transcriptomic data for A. trifoliata fruit. A total of 10 AktWOXs were classified into modern (6), intermediate (2) and ancient clades (2) and all AktWOXs had undergone strong purifying selection during evolution. The expression profile of AktWOXs during A. trifoliata adventitious root formation indicated that AktWOXs play an important role in the regulation of adventitious root development. Overall, this is the first study to identify and characterize the WOX family in A. trifoliata and will be helpful for further research on A. trifoliata adventitious root formation.