The allelic compositions of high- and low-molecular-weight subunits of glutenins (HMW-GS and LMW-GS) among European spelt ( Triticum spelta L.) and related hexaploid and tetraploid Triticum species were investigated by one- and two-dimensional polyacrylamide-gel electrophoresis (PAGE) and capillary electrophoresis (CE). A total of seven novel glutenin alleles (designated A1a*, B1d*, B1g*, B1f*, B1j*, D1a* at Glu-1 and A3h at the Glu-3 loci, respectively) in European spelt wheat were detected by SDS-PAGE, which were confirmed further by employing A-PAGE and CE methods. Particularly, two HMW-GS alleles, Glu-B1d* coding the subunits 6.1 and 22.1, and Glu-B1f* coding the subunits 13 and 22*, were found to occur in European spelt with frequencies of 32.34% and 5.11%, respectively. These two alleles were present in cultivated emmer (Triticum dicoccum), but they were not observed in bread wheat (Triticum aestivum L.). The allele Glu-B1g* coding for 13* and 19* subunits found in spelt wheat was also detected in club wheat (Triticum compactum L.). Additionally, two alleles coding for LMW-GS, Glu-A3h and Glu-B3d, occurred with high frequencies in spelt, club and cultivated emmer wheat, whereas these were not found or present with very low frequencies in bread wheat. Our results strongly support the secondary origin hypothesis, namely European spelt wheat originated from hybridization between cultivated emmer and club wheat. This is also confirmed experimentally by the artificial synthesis of spelt through crossing between old European emmer wheat, T. dicoccum and club wheat, T. compactum.

A wheat cultivar “Chinese Spring” chromosome substitution line CS-1Sl(1B), in which the 1B chromosome was substituted by 1Sl from Aegilops longissima, was developed and found to possess superior dough and breadmaking quality. The molecular mechanism of its super quality conformation is studied in the aspects of high molecular glutenin genes, protein accumulation patterns, glutenin polymeric proteins, protein bodies, starch granules, and protein disulfide isomerase (PDI) and PDI-like protein expressions. Results showed that the introduced HMW-GS 1Sl×2.3* and 1Sly16* in the substitution line possesses long repetitive domain, making both be larger than any known x- and y-type subunits from B genome. The introduced subunit genes were also found to have a higher level of mRNA expressions during grain development, resulting in more HMW-GS accumulation in the mature grains. A higher abundance of PDI and PDI-like proteins was observed which possess a known function of assisting disulfide bond formation. Larger HMW-GS deposited in protein bodies were also found in the substitution line. The CS substitution line is expected to be highly valuable in wheat quality improvement since the novel HMW-GS are located on chromosome 1Sl, making it possible to combine with the known superior D×5+Dy10 subunits encoded by Glu-D1 for developing high quality bread wheat.

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Powdery mildew, caused by the fungus Erysiphe graminis DC. ex Merat f. sp. tritici Em. Marchal, is a serious disease of cultivated bread wheat, Triticum aestivum L. em Thell. About 20 powdery mildew resistance genes are known in wheat and most of them are used in cultivar improvement. however, many of these genes were overcome by th funus and are no longer effective and therefre, new sources of resistance are continuously being sought. recently, we reported a new source of powdery mildew resistance, preliminarily desinated MIP6L, that was derived from the long arm of chromosome 6R of secale cereale L. cv. Prolific. the aim of this study was to transfer MIP6L to a cytologically stable wheat‐rye chromosome translocation. Here we report the transfer of MIP6L from a monosomic 6RL (6D) chromosome substitution line by homologous recomination to a cytologically stable T6BS‐6RL weat‐rye chromosome translocation. The powdery mildew resistance gene was desinated Pm20. The powdery mildew resistance gene was designated Pm20. C‐banding analysis was used to physically map Pm20 in the distal third of the recombined translocation chromosome T6BS 6RLrec.. The succesful transfer of the resistance gene was veriied by artificial inoculation with the powdery mildew funus. Furthermore, a strategy for transferring additional useful genes from alien species to wheat is discussed.

Three novel low molecular weight (LMW) glutenin subunits from cultivated einkorn (Triticum monococcum L., A(m)A(m), 2n = 2x = 14) were characterized by SDS-PAGE and molecular weights determined by MALDI-TOF-MS. Their coding genes were amplified and cloned with designed AS-PCR primers, revealing three complete gene sequences. All comprised upstream, open reading frame (ORF), downstream and no introns were present. The deduced amino acid sequences showed that all three genes, named as LMW-M1, LMW-M3 and LMW-M5, respectively, belonged to the LMW-i type subunits with the predicted molecular weight between 38.5206 and 38.7028 kDa. They showed high similarity with other LMW-i type genes from hexaploid bread wheats, but also displayed unique features. Particularly, LMW-M5 subunit contained an extra cysteine residue in the C-terminus except for eight conserved cysteines, which resulted from a single-nucleotide polymorphism (SNP) of the T-C transition, namely arginine --> cysteine substitution at position 242 from the N-terminal end. This is the first report that the LMW-i subunit contained nine cysteines residues that could result in a more highly cross-linked and more elastic glutenin suggesting that LMW-M5 gene may associates with good quality properties. In addition, a total of 25 SNPs and one insertions/deletions (InDels) were detected among three LMW-i genes, which could result in significant functional changes in polymer formation of gluten. It is anticipated that these SNPs could be used as reliable genetic markers during wheat quality improvement. The phylogenetic analysis indicated that LMW-i type genes apparently differed from LMW-m and LMW-s type genes and diverged early from the primitive LMW-GS gene family, at about 12.92 million years ago (MYA) while the differentiation of A(m) and A genomes was estimated at 3.98 MYA.

A total of 7654 DNA fragments were screened for linkage to wheat powdery mildew resistance gene Pm1c employing fluorescently based AFLP analysis and phenotypic pools from F3 families. F3 and derived F4 families were used for segregation analysis. Pool screening revealed several cosegregating and tightly linked (0.9 cM) AFLP markers for the Pm1c resistance gene. The previously reported RFLP locus Xwhs178 was integrated into the AFLP map in the vicinity of Pm1c. One AFLP marker, 18M2, was determined to be highly specific for the Pm1c gene in diverse genetic backgrounds. As Pm1c allele confers an effective resistance to powdery mildew, the marker 18M2 provides a valuable tool for enhancing marker assisted selection and pyramiding of powdery mildew resistance genes in wheat.Key words: Triticum aestivum, powdery mildew, disease resistance, AFLP, bulked segregant analysis

Major genes for resistance to powdery mildew were analysed in 24 Czechoslovakian wheat cultivars and, in part, in their parents. For this purpose individual isolates of the pathogen, able to differentiate host lines with known resistance genes, were selected. Eight of nineteen winter wheat cultivars do not possess any major resistance gene. Three cultivars have one and seven have two genes. One cultivar carries a combination of three genes {Pm2, Pm4b, Pm8). The most common resistance genes are Pm4b, Pm5 and Pm8. Pm2 is once combined with Pm6. Only one of five spring cultivars lacked a major resistance gene. Mlk is once present alone and twice combmed with Pm5. There is one spring cultivar with a novel combination of three genes: Pml, Pm5 and another gene needing further characterization. The observations are discussed with additional results of parent lines and further information on pedigrees.

Tan spot, caused by the fungus Pyrenophora tritici-repentis (Died.) Drechs. (Ptr), anamorph Drechslera tritici-repentis (Died.) Shoem., is becoming a major yield limiting leaf disease of both durum (Triticum turgidum L. var durum) and common wheat (Triticum aestivum L.) worldwide. In this study, differential isolates and varieties were developed, and using the most virulent isolate, ASC1b, we screened about 100 synthetic wheat genotypes against the disease. Two (2%) and 20 (20.4%) of the genotypes were found to be immune and highly resistant, respectively. Monosomic analyses of the F 2 hybrids (crosses of the highly resistant accessions (XX41, XX45) and the moderately resistant accession XX110 with the monosomic lines (D-genome) of the wheat cultivar Chinese Spring have revealed that the resistance genes are located on chromosome 3D. The gene in lines XX41 and XX110 showed a recessive monogenic inheritance, whereas the gene in line XX45 exhibited a dominant mode of inheritance. The recessive genes from XX41 and XX110 are tentatively named tsn3 and tsn-syn1, respectively, and the dominant gene from XX45 is named as Tsn-syn2.