Discovery of powdery mildew resistance gene candidates from Aegilops biuncialis chromosome 2Mb based on transcriptome sequencing

Abstract

Powdery mildew is one of the most widespread diseases of wheat. The development and deployment of resistant varieties are one of the most economical and effective methods to manage this disease. Our previous study showed that the gene(s) at 2Mb in Chinese Spring (CS)-Aegilops biuncialis 2Mb disomic addition line TA7733 conferred a high level of resistance to powdery mildew of wheat. In this study, resistance spectrum of TA7733 was assayed by using 15 Blumeria graminis f. sp. tritici (Bgt) isolates prevalent in different regions of China. The result indicated that TA7733 was highly resistant to all tested Bgt isolates and the gene(s) on chromosome 2Mb conferred broad-spectrum resistance to powdery mildew. In order to characterize mechanism of powdery mildew resistance by identifying candidates R-genes derived from Ae. biuncialis chromosome 2Mb and develop 2Mb-specific molecular markers, we performed RNA-seq analysis on TA7733 and CS. In total we identified 7,278 unigenes that showed specific expression in TA7733 pre and post Bgt-infection when compared to CS. Of these 7,278 unigenes, 295 were annotated as putative resistance (R) genes. Comparatively analysis of R-gene sequences from TA7733 and CS and integration CS Ref Seq v1.0 were used to develop R-gene specific primers. Of 295 R-genes we identified 53 R-genes were specific to 2Mb and could be involved in powdery mildew resistance. Functional annotation of majority of the 53 R-genes encoded nucleotide binding leucine rich repeat (NLR) protein. The broad-spectrum resistance to powdery mildew in TA7733 and availability of 2Mb-derived putative candidate R-gene specific molecular markers identified in this study will lay foundations for transferring powdery mildew resistance from 2Mb to common wheat by inducing CS-Ae. biuncialis homoeologous recombination. Our study also provides useful candidates for further isolation and cloning of powdery mildew resistance gene(s) from Ae. biuncialis chromosome 2Mb.

Genotype-Specific Expression and NLR Repertoire Contribute to Phenotypic Resistance Diversity in Plantago lanceolata

“…We detected powdery mildew spores growing on the inoculated, susceptible plant leaves on day 14 post inoculation, whereas none of the mock-inoculated or inoculated resistant plant clones showed visible disease symptoms. Several studies of gene expression induced by powdery mildew in host plants have found the highest number of differentially expressed genes in later time points ( Li et al, 2016 , 2019 ; Polonio et al, 2019 ). Accordingly, transcript levels of the marker genes varied considerably in the susceptible plants and showed elevated levels only at time point 72 h post inoculation (hpi; Supplementary Figure 1 ) and therefore this time point was selected for RNA sequencing.…”

Molecular Cytogenetic Identification of Wheat-Aegilops Biuncialis 5Mb Disomic Addition Line with Tenacious and Black Glumes

“…biuncialis disomic addition lines (1U b , 2U b , 2M b , 3U b , 3M b , 5U b , 6M b , 6U b and 7U b ) were created in different wheat backgrounds [47][48][49]53]. These addition lines showed distinct agronomic traits, such as seed storage protein profile [47], disease resistance [54] and drought tolerance [53], which were of great importance to discovering genes carried by each Ae. biuncialis chromosome.…”

Combating powdery mildew: Advances in molecular interactions between Blumeria graminis f. sp. tritici and wheat

“…The establishment of TA7733 broad-spectrum resistance to Bgt and availability of putative candidate R-gene specific molecular markers derived from 2M b laid a foundation for transferring powdery mildew resistance from 2M b to common wheat by inducing CS-Ae. biuncialis homoeologous recombination (Li et al, 2019). Using bulked segregant RNA-Seq, Ma and colleagues analyzed 2 973 differentially expressed genes to study resistance gene regulatory genes.…”