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Wheat powdery mildew possesses a significant threat to wheat crops not only on a global scale but also in the northern region of Pakistan. Recognizing the need for effective measures, the exploration and utilization of exotic germplasm take on critical importance. To address this, a series of trials were made to investigate the response of 30 European (EU) lines, in addition to the local checks (Siran, Atta-Habib (AH) and Ghanimat-e-IBGE) against wheat powdery mildew at the Himalayan region of Pakistan. The study involved field testing from 2018 to 2022 across multiple locations, resulting in 38 different environments (location × year). In addition to field evaluations, molecular genotyping was also performed. The disease was absent on the tested lines during 2018, 2019, and 2020 whereas it ranged from 0 to 100% at Chitral location during 2021, where 100% was observed only for one EU wheat line "Matrix." The disease prevailed only at Gilgit location (0–60% for EU wheat line "F236") and at Nagar location (0–10% for EU wheat lines Substance and Nelson) during the disease season of 2022. Most of the EU wheat lines showed very low ACI values, due to an overall low disease pressure. Matrix showed the maximum ACI (1.54) followed by Ritter (1.25) and Bli_autrichion (0.87), whereas the minimum (0.1) was for Substance, JB_Asano, and KWS_Loft followed by Canon (0.19), all exhibiting partial resistance. The molecular marker-based screening revealed that Pm38 was the most prevalent and detected in 100% of wheat lines followed by Pm39 (60%) and Pm8 (30%). Six wheat lines (20%) possessed all three Pm genes (Pm8, Pm38, and Pm39) concurrently. The variability observed in this study can be utilized in future breeding efforts aimed at developing resistant wheat varieties. [ABSTRACT FROM AUTHOR]

Landraces of maize (Zea mays L.) have a variability not found in the elite hybrids due to the bottleneck during selection. There is a renewed interest in using that variability, incorporating alleles for specific traits, or widening the general variability of elite germplasm. In Europe, there is also an interest in the direct use of local landraces by farmer's associations seeking agriculture that preserves crop diversity. Pre-breeding programs are aimed to reduce the yield gap among landraces and improved materials. In the Misión Biológica de Galicia we have carried out three cycles of a S1 recurrent selection program for yield on four local landraces from Northwestern Spain with the objective of obtaining improved populations that might be cultivated by farmers and that could be used as sources of superior inbred lines. One hundred plants were selfed in each landrace and the S1 families were evaluated in a 10 × 10 simple lattice. The 20 S1 families with the highest grain yields were randomly intercrossed to form the selected population of each landrace. After three cycles of selection, each population and its cycles of selection were evaluated in three locations for two years. All the populations had a consistent yield gain in the first cycle of selection. However, the response in later cycles differed among the populations: one population had a continuous increase of 21% per cycle while two populations had a reduced yield in the last cycles. Our results highlight the need to include secondary traits to avoid unintentional indirect effects. We conclude that, in pre-breeding programs, it could be worthy to use large effective numbers to prevent inbreeding depression, particularly when the objective is the direct use of improved landraces. Another conclusion is that recurrent selection does not seem to be as efficient on European germplasm as it is on Corn Belt varieties. Finally, obtaining valuable new germplasm requires a sustained, long-term effort. [ABSTRACT FROM AUTHOR]

Abstract Background Maize is well known for its exceptional structural diversity, including copy number variants (CNVs) and presence/absence variants (PAVs), and there is growing evidence for the role of structural variation in maize adaptation. While PAVs have been described in this important crop species, they have been only scarcely characterized at the sequence level and the extent of presence/absence variation and relative chromosomal landscape of inbred-specific regions remain to be elucidated. Results De novo genome sequencing of the French F2 maize inbred line revealed 10,044 novel genomic regions larger than 1 kb, making up 88 Mb of DNA, that are present in F2 but not in B73 (PAV). This set of maize PAV sequences allowed us to annotate PAV content and to analyze sequence breakpoints. Using PAV genotyping on a collection of 25 temperate lines, we also analyzed Linkage Disequilibrium in PAVs and flanking regions, and PAV frequencies within maize genetic groups. Conclusions We highlight the possible role of MMEJ-type double strand break repair in maize PAV formation and discover 395 new genes with transcriptional support. Pattern of linkage disequilibrium within PAVs strikingly differs from this of flanking regions and is in accordance with the intuition that PAVs may recombine less than other genomic regions. We show that most PAVs are ancient, while some are found only in European Flint material, thus pinpointing structural features that may be at the origin of adaptive traits involved in the success of this material. Characterization of such PAVs will provide useful material for further association genetic studies in European and temperate maize.

Early vigor, earliness and cold tolerance are the main potential contributions of European maize ( Zea mays L.) for breeding programs for adaptation to areas with short growing seasons and cold springs. The objective of this research was to determine the potential contributions of populations from different European regions to breeding for adaptation. Six Spanish and six French maize populations differing on variability for earliness, vigor and cold tolerance were crossed in a complete diallel without reciprocals. The populations and their crosses were evaluated in the field and in a cold chamber. Minimum temperatures were the main environmental trait affecting genotype × environment interaction, probably due to the cold sensitivity of the genotypes with the best performance in the field. The best population cross, based on specific heterosis for adaptation-related traits in the field, was Viana × Rastrojero, but this cross was cold sensitive. Tuy × Lazcano should be the best choice for a breeding program for adaptation, based on performance in the field and cold tolerance. As conclusions, there was variability for earliness, vigor and cold tolerance among the populations and crosses involved in this study, being tolerant to cold conditions the populations with medium growing cycle originated in areas with short growing seasons. The highest yielding crosses were cold sensitive. [ABSTRACT FROM AUTHOR]