Wheat powdery mildew, caused by Blumeria graminis (DC.) Speer f. sp. tritici is a destructive disease seriously threatening yield and quality of common wheat (Triticum aestivum L., 2n=6x=42, AABBDD). Characterization of resistance genes against powdery mildew is useful in parental selection and for developing disease-resistant cultivars. Chinese wheat breeding line KN0816 has superior agronomic performance and resistance to powdery mildew at all growth stages. Genetic analysis using populations of KN0816 crossed with different susceptible parents indicated that a single dominant gene, tentatively designated PmKN0816, conferred seedling resistance to different B. graminis f. sp. tritici isolates. Using a bulked segregant analysis, PmKN0816 was mapped to the Pm6 interval on chromosome arm 2BL using polymorphic markers linked to the cataloged genes Pm6, Pm52, and Pm64, and flanked by the markers CISSR02g-6 and CIT02g-2, both with genetic distances of 0.7 cM. Analysis of closely linked molecular markers indicated that the marker alleles of PmKN0816 differed from those of other powdery mildew resistance genes on 2BL, including Pm6, Pm33, Pm51, Pm64, and PmQ. Based on the genetic and physical locations and response pattern to different B. graminis f. sp. tritici isolates, PmKN0816 is most likely a new powdery mildew resistance gene and possesses effective resistance to all the 14 tested B. graminis f. sp. tritici isolates. In view of the elite agronomic performance of KN0816 combined with the resistance, PmKN0816 is expected to become a valuable resistance gene in wheat breeding. To transfer PmKN0816 to different genetic backgrounds using marker-assisted selection (MAS), closely linked markers of PmKN0816 were evaluated, and four of them (CIT02g-2, CISSR02g-6, CIT02g-10, and CIT02g-17) were confirmed to be applicable for MAS in different genetic backgrounds.

Genetic dissection kernel weight-related traits is of great significance for improving wheat yield potential. As one of the three major yield components of wheat, thousand kernel weight (TKW) was mainly affected by grain length (GL) and grain width (GW). To uncover the key loci for these traits, we carried out a quantitative trait loci (QTL) analysis of an F₆ recombinant inbred lines (RILs) population derived from a cross of Henong 5290 (small grain) and 06Dn23 (big grain) with a 50 K single nucleotide polymorphism (SNP) array. A total of 17 stable and big effect QTL, including 5 for TKW, 8 for GL and 4 for GW, were detected on the chromosomes 1B, 2A, 2B, 2D, 4B, 5A, 6A and 6D, respectively. Among these, there were two co-located loci for three traits that were mapped on the chromosome 4BS and 6AL. The QTL on 6AL was the most stable locus and explained 15.4–24.8%, 4.1–8.8% and 15.7–24.4% of TKW, GW and GL variance, respectively. In addition, two more major QTL of GL were located on chromosome arm 2BL and 2DL, accounting for 9.7–17.8% and 13.6–19.8% of phenotypic variance, respectively. In this study, we found one novel co-located QTL associated with GL and TKW in 2DL, QGl.haaf-2DL.2/QTkw.haaf-2DL.2, which could explain 13.6–19.8% and 9.8–10.7% phenotypic variance, respectively. Genetic regions and linked markers of these stable QTL will help to further refine mapping of the corresponding loci and marker-assisted selection (MAS) breeding for wheat grain yield potential improvement.

Wheat powdery mildew is a devastating disease that seriously threatens yield worldwide. Utilization of host resistance is considered an effective strategy to minimize powdery mildew damage. Pm21, PmV, and Pm12 confer broad-spectrum resistance to wheat powdery mildew in China, of which Pm21 and PmV are allelic genes derived from the 6VS chromosome of Dasypyrum villosum, and Pm12 is derived from the 6SS chromosome of Aegilops speltoides and most likely orthologous to the former two genes. To accurately and efficiently transfer and pyramid these genes using marker-assisted selection (MAS), distinctive single-nucleotide polymorphisms (SNPs) among the exon sequences of Pm21, PmV, and Pm12 and their homologous sequences in the common wheat genome were identified and then used for developing diagnostic Kompetitive Allele-Specific PCR (KASP) markers. The markers were validated in different genotypes including transgenic vectors, transgenic lines, translocation lines, resistance stocks with documented Pm genes, and in multiple susceptible cultivars without Pm genes. As a result, we initially developed a KASP marker that can simultaneously diagnose Pm21, Pm12, and PmV. Subsequently, we obtained a highly diagnostic KASP marker for each of the three genes that could distinguish among the three genes and also accurately distinguish them from other resistant stocks with documented Pm genes and from multiple susceptible genotypes. Compared with previously reported markers, the highly diagnostic KASP markers developed in this study have the advantages of low cost, easy assay, accuracy, and potentially high throughput for MAS.

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is a devastating disease that threatens yield and quality. Host resistance is considered the most effective and preferred means to control this disease. Wheat landrace Duanganmang (DGM) showed high resistance or near immunity to Blumeria graminis f. sp. tritici mixture from Henan Province, China. DGM was crossed with highly susceptible Chinese wheat landrace Huixianhong (HXH) and cultivar ‘Shimai 15’ (SM15) to produce genetic populations. The resistance of DGM to Blumeria graminis f. sp. tritici isolate E09 was shown to be controlled by a single dominant Mendelian factor, tentatively designated PmDGM. Marker analysis and 55K single nucleotide polymorphism (SNP) array scanning showed that this gene was positioned in the Pm5 interval (2.4 cM or 1.61 Mb) flanked by Xhenu099 and Xmp1158 in the Chinese Spring reference genome. Homology-based cloning and sequence analysis demonstrated that DGM has the identical NLR gene (Pm5e) and RXL gene reported in Fuzhuang 30 (FZ30), conferring and modifying powdery mildew resistance, respectively. However, based on the different reaction patterns to the Blumeria graminis f. sp. tritici isolate B15 between DGM and FZ30, the authors speculate that DGM may have two tightly linked genes that could not be separated in the current mapping population, one of which is PmDGM and the other being Pm5e. Hence, this study provides a valuable resistance resource for improvement of powdery mildew resistance.

The increasing temperature is a major threat to plant growth and development. It severely alters various biochemical and physiological processes and ultimately affects the overall crop yield. The membrane-based remorin protein-encoding genes (REM) were previously reported as significantly involved in the regulation of various biotic and abiotic stressors. However, these REM genes were not studied in Cajanus Cajan, the sixth most important legume crop due to its rich protein source and traditional medicinal plant. In this study, 17 REM gene orthologs were identified in C. cajan against A. thaliana REM genes and verified through the presence of conserved REM-related domains. Phylogenetic analysis revealed that REM genes were divided into six different groups. All the REM genes were unevenly distributed on 11 chromosomes of C. cajan. 3D protein structures and intron-exon organization indicate conserved evolutionary pattern within C. cajan. Various core, hormone-responsive, and stress-responsive cis-regulatory elements were found in promoter regions of REM genes, including TATA-box, CAAT-box, MYB, and G-box. The total estimation of antioxidant enzyme activity revealed the increase in POD and SOD activity, potentially due to a defense mechanism in response to high temperature. RNA sequencing data processing reveals higher expression of CcREM genes in leaf and flower, including CcREM1.1 and CcREM1.2. Furthermore, the differential change in expression was observed in response to high-temperature stress. Among these genes, one upregulated gene (CcREM1.3) and two downregulated genes (CcREM6.1 and CcREM6.5) are potential candidate targets for heat stress response, followed by qRT-PCR validation. Our findings suggest that CcREM1-like and CcREM6-like genes hold significant potential for future climate-smart heat-tolerant breeding of C. cajan.