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Abstract Fungal diseases, such as powdery mildew and rusts, significantly affect the quality and yield of wheat. Pyramiding diverse types of resistance genes into cultivars represents the preferred strategy to combat these diseases. Moreover, achieving collaborative improvement between diseases resistance, abiotic stress, quality, and agronomic and yield traits is difficult in genetic breeding. In this study, the wheat cultivar, Guinong 29 (GN29), showed high resistance to powdery mildew and stripe rust at both seedling and adult plant stages, and was susceptible to leaf rust at the seedling stage but slow resistance at the adult-plant stage. Meanwhile, it has elite agronomic and yield traits, indicating promising coordination ability among multiple diseases resistance and other key breeding traits. To determine the genetic basis of these elite traits, GN29 was tested with 113 molecular markers for 98 genes associated with diseases resistance, stress tolerance, quality, and adaptability. The results indicated that two powdery mildew resistance (Pm) genes, Pm2 and Pm21, confirmed the outstanding resistance to powdery mildew through genetic analysis, marker detection, genomic in situ hybridization (GISH), non-denaturing fluorescence in situ hybridization (ND-FISH), and homology-based cloning; the stripe rust resistance (Yr) gene Yr26 and leaf rust resistance (Lr) genes Lr1 and Lr46 conferred the stripe rust and slow leaf rust resistance in GN29, respectively. Meanwhile, GN29 carries dwarfing genes Rht-B1b and Rht-D1a, vernalization genes vrn-A1, vrn-B1, vrn-D1, and vrn-B3, which were consistent with the phenotypic traits in dwarf characteristic and semi-winter property; carries genes Dreb1 and Ta-CRT for stress tolerance to drought, salinity, low temperature, and abscisic acid (ABA), suggesting that GN29 may also have elite stress-tolerance ability; and carries two low-molecular-weight glutenin subunit genes Glu-B3b and Glu-B3bef which contributed to high baking quality. This study not only elucidated the genetic basis of the elite traits in GN29 but also verified the capability for harmonious improvement in both multiple diseases resistance and other comprehensive traits, offering valuable information for breeding breakthrough-resistant cultivars.

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most destructive fungal diseases threatening global wheat production. Exploring powdery mildew resistance (Pm) gene(s) and dissecting the molecular mechanism of the host resistance are critical to effectively and reasonably control this disease. Durum wheat (Triticum turgidum L. var. durumDesf.) is an important gene donor for wheat improvement against powdery mildew. In this study, a resistant durum wheat accession W762 was used to investigate its potential resistance component(s) and profile its expression pattern in responding to Bgt invasion using bulked segregant RNA-Seq (BSR-Seq) and further qRT-PCR verification. Genetic analysis showed that the powdery mildew resistance in W762 did not meet monogenic inheritance and complex genetic model might exist within the population of W762 × Langdon (susceptible durum wheat). After BSR-Seq, 6,196 consistently different single nucleotide polymorphisms (SNPs) were called between resistant and susceptible parents and bulks, and among them, 763 SNPs were assigned to the chromosome arm 7B. Subsequently, 3,653 differentially expressed genes (DEGs) between resistant and susceptible parents and bulks were annotated and analyzed by Gene Ontology (GO), Cluster of Orthologous Groups (COG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. The potential regulated genes were selected and analyzed their temporal expression patterns following Bgt inoculation. As a result, nine disease-related genes showed distinctive expression profile after Bgt invasion and might serve as potential targets to regulate the resistance against powdery mildew in W762. Our study could lay a foundation for analysis of the molecular mechanism and also provide potential targets for the improvement of durable resistance against powdery mildew.

Powdery mildew is one of the most severe diseases affecting wheat yield and quality and is caused by Blumeria graminis f. sp. tritici (Bgt). Host resistance is the preferred strategy to prevent this disease. However, the narrow genetic basis of common wheat has increased the demand for diversified germplasm resources against powdery mildew. Wheat relatives, especially the secondary gene pool of common wheat, are important gene donors in the genetic improvement of common wheat because of its abundant genetic variation and close kinship with wheat. In this study, a series of 137 wheat relatives, including 53 Triticum monococcum L. (2n = 2x = 14, AA), 6 T. urartu Thumanjan ex Gandilyan (2n = 2x = 14, AA), 9 T. timopheevii Zhuk. (2n = 4x = 28, AAGG), 66 T. aestivum subsp. spelta (2n = 6x = 42, AABBDD), and 3 Aegilops speltoides (2n = 2x = 14, SS) were systematically evaluated for their powdery mildew resistance and composition of Pm genes. Out of 137 (60.58%) accessions, 83 were resistant to Bgt isolate E09 at the seedling stage, and 116 of 137 (84.67%) wheat relatives were resistant to the mixture of Bgt isolates at the adult stage. This indicates that these accessions show a high level of resistance to powdery mildew. Some 31 markers for 23 known Pm genes were used to test these 137 accessions, and, in the results, only Pm2, Pm4, Pm6, Pm58, and Pm68 were detected. Among them, three Pm4 alleles (Pm4a, Pm4b, and Pm4f) were identified in 4 T. subsp. spelta accessions. q-RT PCR further confirmed that Pm4 alleles played a role in disease resistance in these four accessions. The phylogenetic tree showed that the kinship of Pm4 was close to Pm24 and Sr62. This study not only provides reference information and valuable germplasm resources for breeding new wheat varieties with disease resistance but also lays a foundation for enriching the genetic basis of wheat resistance to powdery mildew.

Powdery mildew of wheat (Triticum aestivum), caused by Blumeria graminis f.sp. tritici (Bgt), is a destructive disease that seriously threatens the yield and quality of its host. Identifying resistance genes is the most attractive and effective strategy for developing disease-resistant cultivars and controlling this disease. In this study, a wheat breeding line Yannong 99102-06188 (YN99102), an elite derivative line from the same breeding process as the famous wheat cultivar Yannong 999, showed high resistance to powdery mildew at the whole growth stages. Genetic analysis was carried out using Bgt isolate E09 and a population of YN99102 crossed with a susceptible parent Jinhe 13–205 (JH13–205). The result indicated that a single recessive gene, tentatively designated pmYN99102, conferred seedling resistance to the Bgt isolate E09. Using bulked segregant exome capture sequencing (BSE-Seq), pmYN99102 was physically located to a ~33.7 Mb (691.0–724.7 Mb) interval on the chromosome arm 2BL, and this interval was further locked in a 1.5 cM genetic interval using molecular markers, which was aligned to a 9.0 Mb physical interval (699.2–708.2 Mb). Based on the analysis of physical location, origin, resistant spectrum, and inherited pattern, pmYN99102 differed from those of the reported powdery mildew (Pm) resistance genes on 2BL, suggesting pmYN99102 is most likely a new Pm gene/allele in the targeted interval. To transfer pmYN99102 to different genetic backgrounds using marker-assisted selection (MAS), 18 closely linked markers were tested for their availability in different genetic backgrounds for MAS, and all markers expect for YTU103-97 can be used in MAS for tracking pmYN99102 when it transferred into those susceptible cultivars.