Molecular cytogenetics for a wheat–Aegilops geniculata 3Mg alien addition line with resistance to stripe rust and powdery mildew

Background Aegilops geniculata Roth is closely related to common wheat (Triticum aestivum L.) and is a valuable genetic resource for improvement of wheat. Results In this study, the W19513 line was derived from the BC1F10 progeny of a cross between wheat ‘Chinese Spring’ and Ae. geniculata SY159. Cytological examination showed that W19513 contained 44 chromosomes. Twenty-two bivalents were formed at the first meiotic metaphase I in the pollen mother cellsand the chromosomes were evenly distributed to opposite poles at meiotic anaphase I. Genomic in situ hybridization demonstrated that W19513 carried a pair of alien chromosomes from the M genome. Fluorescence in situ hybridization confirmed detection of variation in chromosomes 4A and 6B. Functional molecular marker analysis using expressed sequence tag–sequence-tagged site and PCR-based landmark unique gene primers revealed that the alien gene belonged to the third homologous group. The marker analysis confirmed that the alien chromosome pair was 3Mg. In addition, to further explore the molecular marker specificity of chromosome 3Mg, based on the specific locus amplified fragment sequencing technique, molecular markers specific for W19513 were developed with efficiencies of up to 47.66%. The W19513 line was inoculated with the physiological race E09 of powdery mildew (Blumeria graminis f. sp. tritici) at the seedling stage and showed moderate resistance. Field inoculation with a mixture of the races CYR31, CYR32, CYR33, and CYR34 of the stripe rust fungus (Puccinia striiformis f. sp. triticii) revealed that the line W19513 showed strong resistance. Conclusions This study provides a foundation for use of the line W19513 in future genetic research and wheat improvement.

Molecular Cytogenetics and SLAF-seq-based Specific Molecular Markers for a Wheat–Aegilops geniculata 3M g Alien Addition Line with Resistance to Stripe Rust and Powdery Mildew

Background: Aegilops geniculata Roth is closely related to common wheat (Triticum aestivum L.) and is a valuable genetic resource for improvement of wheat. Results: In this study, the W19513 line was derived from the BC1F10 progeny of a cross between wheat ‘Chinese Spring’ and Ae. geniculata SY159. Cytological examination showed that W19513 contained 44 chromosomes. Twenty-two bivalents were formed at the first meiotic metaphase in the pollen mother cells, and the chromosomes were evenly distributed to opposite poles at meiotic anaphase. Genomic in situ hybridization demonstrated that W19513 carried a pair of alien chromosomes from the M genome. Fluorescence in situ hybridization confirmed detection of variation in chromosomes 4A and 6B. Functional molecular marker analysis using expressed sequence tag–sequence-tagged site and PCR-based landmark unique gene primers revealed that the alien gene belonged to the third homologous group. The marker analysis confirmed that the alien chromosome pair was 3Mg. In addition, to further explore the molecular marker specificity of chromosome 3Mg, based on the specific locus amplified fragment sequencing technique, molecular markers specific for W19513 were developed with efficiencies of up to 47.66%. The W19513 line was inoculated with the physiological race E09 of powdery mildew (Blumeria graminis f. sp. tritici) at the seedling stage and showed moderate resistance. Field inoculation with a mixture of the races CYR31, CYR32, CYR33, and CYR34 of the stripe rust fungus (Puccinia striiformis f. sp. triticii) revealed that the line W19513 showed strong resistance.Conclusions: This study provides a foundation for use of the line W19513 in future genetic research and wheat improvement.

Characterization and Evaluation of Resistance to Powdery Mildew of Wheat–Aegilops geniculata Roth 7Mg (7A) Alien Disomic Substitution Line W16998

Aegilops geniculata Roth has been used as a donor of disease-resistance genes, to enrich the gene pool for wheat (Triticum aestivum) improvement through distant hybridization. In this study, the wheat–Ae. geniculata alien disomic substitution line W16998 was obtained from the BC1F8 progeny of a cross between the common wheat ‘Chinese Spring’ (CS) and Ae. geniculata Roth (serial number: SY159//CS). This line was identified using cytogenetic techniques, analysis of genomic in situ hybridization (GISH), functional molecular markers (Expressed sequence tag-sequence-tagged site (EST–STS) and PCR-based landmark unique gene (PLUG), fluorescence in situ hybridization (FISH), sequential fluorescence in situ hybridization–genomic in situ hybridization (sequential FISH–GISH), and assessment of agronomic traits and powdery mildew resistance. During the anaphase of meiosis, these were evenly distributed on both sides of the equatorial plate, and they exhibited high cytological stability during the meiotic metaphase and anaphase. GISH analysis indicated that W16998 contained a pair of Ae. geniculata alien chromosomes and 40 common wheat chromosomes. One EST–STS marker and seven PLUG marker results showed that the introduced chromosomes of Ae. geniculata belonged to homoeologous group 7. Nullisomic–tetrasomic analyses suggested that the common wheat chromosome, 7A, was absent in W16998. FISH and sequential FISH–GISH analyses confirmed that the introduced Ae. geniculata chromosome was 7Mg. Therefore, W16998 was a wheat–Ae. geniculata 7Mg (7A) alien disomic substitution line. Inoculation of isolate E09 (Blumeria graminis f. sp. tritici) in the seedling stage showed that SY159 and W16998 were resistant to powdery mildew, indeed nearly immune, whereas CS was highly susceptible. Compared to CS, W16998 exhibited increased grain weight and more spikelets, and a greater number of superior agronomic traits. Consequently, W16998 was potentially useful. Germplasms transfer new disease-resistance genes and prominent agronomic traits into common wheat, giving the latter some fine properties for breeding.

Hybridization potential Aegilops sp. / durum wheat: which interest for the genetic breeding of the drought tolerance?

<p>To study their hybridization potential, two species of the genus <em>Aegilops</em> (<em>Aegilops geniculata </em>Roth; <em>Aegilops triuncialis</em> L.) and two durum wheat (<em>Triticum durum </em>Desf.) varieties (‘Oued Zenati’ and ‘Hoggar’) were crossed, where <em>Aegilops</em> was the female parent. The four cross combinations were tested during five years in order to release the genitors having the most affinity for obtaining interspecific hybrids. The parents were also characterized for their drought stress tolerance during the crossing period. The results confirm the tolerance of <em>Aegilops </em>sp. and adaptation of the durum wheat varieties to climatic conditions governing the Algerian cereal zones. 81 hybrids F1 were obtained. Differences in hybridization affinity between the parents were very remarkable. The combination of parents <em>Aegilops geniculata</em>/’ Oued Zenati’ has produced the highest number of hybrids (54 or a rate of 5.23 %), followed by <em>Aegilops triuncialis</em>/’Oued Zenati’ (18 hybrids or a rate of 3.88 %). The crossing of the two <em>Aegilops</em> species with the Hoggar variety produced a small number of hybrids. Among the advantages of this crossing, the obtaining of hybrids in caryopsis without resorting to the embryos rescue. Hybrid seedlings expressed a maternal cytoplasmic heredity. However, no adult plant could have been regenerated.</p>