Characterization of a Powdery Mildew Resistance Gene in Wheat Breeding Line 10V-2 and Its Application in Marker-Assisted Selection

Abstract

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is a serious disease of wheat (Triticum aestivum L.) throughout the world. Host resistance is the most effective and preferred means for managing this disease. Line 10V-2, a wheat breeding line with superior agronomic performance, shows broad-spectrum seedling resistance to powdery mildew. Genetic analysis demonstrated that its resistance was controlled by a single dominant gene, tentatively designated Pm10V-2. This gene was localized near the documented Pm2 locus on chromosome 5DS using the simple sequence repeat (SSR) marker Cfd81. To saturate the marker map of Pm10V-2, more markers were developed using bulked segregant RNA-Seq. Two single-nucleotide polymorphism (SNP) markers (Swgi047 and Swgi064), three expressed sequence tag markers (Swgi007, Swgi029, and Swgi038), and one SSR marker (Swgi066) were polymorphic between the resistant and susceptible bulks and showed tightly linked to the Pm10V-2 gene. Pm10V-2 was flanked by the new developed markers Swgi064 and Swgi066 at genetic distances of 0.4 and 1.2 centimorgans (cM), respectively, and cosegregated with Swgi007 and Swgi038. The homologous sequence of Pm2a was cloned from 10V-2 based on a recent study. Although the sequence cloned from 10V-2 was completely identical to that of the reported Pm2a-related gene, they did not cosegregate but were separated at a genetic distance of 1.6 cM, indicating that Pm10V-2 was different from the reported of Pm2a-related gene. When inoculated with multiple B. graminis f. sp. tritici isolates, Pm10V-2 had a significantly different resistance spectrum from Pm2a and other powdery mildew (Pm) resistance genes at or near the Pm2 locus. Therefore, Pm10V-2 may be a new Pm2 allele or Pm2-linked gene. To use Pm10V-2 in marker-assisted selection (MAS) breeding, seven markers applicable for MAS were confirmed, including three newly developed markers (Swgi029, Swgi038, and Swgi064) in the present work. Using these markers, a great number of resistant lines with desirable agronomic performance were selected from crosses involving 10V-2, including the breeding line KM5016, which has been entered in the Regional trials in Hebei Province, China.

Characterization of the Powdery Mildew Resistance Gene in the Elite Wheat Cultivar Jimai 23 and Its Application in Marker-Assisted Selection

“…Although this locus has been cloned by mutant chromosome sequencing (Sánchez-Martín et al, 2016) and analysis of the annotated genes in the mapping interval using the reference genome of Chinese Spring , no transgenic evidence was provided to confirm that the cloned sequence is the unique functional element conferring resistance to powdery mildew. Additionally, other reports showed that all the homologous sequences in different Pm2 allele donors have the exactly the same sequence, yet these Pm2 alleles exhibit significantly different resistance spectra that cannot be explained by the background differences of the resistant germplasms (Jin et al, 2018;Ma et al, 2018). In this study, the marker order across the PmJM23 interval showed inversion and recombination phenomena (Figure 2 and Table 3).…”

“…This suggests that Jimai 23 is an elite resource for resistance breeding. Frontiers in Genetics | www.frontiersin.org markers Icssl326 and Icssl795, and when inoculated with isolate YT01 that was avirulent to both Jimai 23 and Liangxing 99 (Pm52), we detected Pm2-linked marker polymorphisms using five Pm2-linked markers (Cfd81, Swgi069, Bwm20, Bwm21, and Bwm25; Ma et al, 2018) and no Pm52-linked marker polymorphism using Pm52-linked markers Icssl326 and Icssl795 in Jimai 23 × Tainong 18 population. By combining the genealogical relationship between Jimai 22 and 23 with the marker detection results, we confirmed that Jimai 23 has a Pm gene nearby or in the Pm2 interval, which we tentatively designate as PmJM23.…”

“…Additionally, the Pm genes derived from landraces usually have poor agronomic performance and need multigeneration backcrossing before acceptance by breeders (Xu et al, 2015;Li et al, 2020). Clearly, the value to breeding of a specific Pm gene depends not only on its effectiveness for disease control but also on the agronomic performance of its donor (Zhao et al, 2013;Ma et al, 2018). The discovery of new genes or new allelic variations from elite wheat cultivars offers an attractive prospect for the rapid genetic improvement of resistance.…”

Scale development and utilization of universal PCR-based and high-throughput KASP markers specific for chromosome arms of rye (Secale cereale L.)

“…The PCR procedure was as follow: 94°C for 5 min, followed by 36 cycles of 94°C for 30 s, 58°C for 30 s, 72°C for 40 s, and a final extension at 72°C for 10 min. The PCR products were separated in 8% non-denaturing polyacrylamide gels with 29:1 ratio of acrylamide and bis-acrylamide, and silver-stained prior to visualizing the banding patterns [68].…”

Genome-Wide Characterization and Comparative Analyses of Simple Sequence Repeats among Four Miniature Pig Breeds

“…Simple sequence repeats (SSRs), also known as microsatellites or short tandem repeats (STRs), consist of 2 to 6 base-pair motifs repeated several times in tandem. As a consequence of their wide distribution and high mutation rate in eukaryotic genomes [ 1 ], SSRs have been used in genetic diversity and population structure studies [ 2 , 3 , 4 , 5 ], for discrimination among species or breeds [ 6 , 7 ], in marker-assisted selection [ 8 , 9 , 10 ] and in evolution analysis [ 11 ]. In humans, SSRs were predicted to be bound by protein-coding transcripts, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) and affect competing endogenous RNA crosstalk [ 12 ].…”