|LIANG, YONG - Chinese Agricultural University
|ZHANG, DEYUN - Chinese Agricultural University
|OUYANG, SHUHONG - Chinese Agricultural University
|XIE, JINGZHONG - Chinese Agricultural University
|WU, QIUHONG - Chinese Agricultural University
|WANG, ZHENZHONG - Chinese Agricultural University
|CUI, YU - Chinese Agricultural University
|LIU, ZI-JI - Chinese Agricultural University
|CHEN, YONG-XING - Chinese Agricultural University
|ZHANG, YAN - Chinese Agricultural University
|LUO, MING-CHENG - University Of California
|DVORAK, JAN - University Of California
|HUO, NAXIN - University Of California
|SUN, QINXIN - Chinese Agricultural University
|LIU, ZHIYONG - Chinese Agricultural University
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2015
Publication Date: 5/21/2015
Citation: Liang, Y., Zhang, D., Ouyang, S., Xie, J., Wu, Q., Wang, Z., Cui, Y., Liu, Z., Chen, Y., Zhang, Y., Luo, M., Dvorak, J., Huo, N., Sun, Q., Gu, Y.Q., Liu, Z. 2015. Dynamic evolution of resistance gene analogs in the orthologous genomic regions of powdery mildew resistance gene MlIW170 in Triticum dicoccoides and Aegilops tauschii. Theoretical and Applied Genetics. 128:1617-1629.
Interpretive Summary: Wheat accounts for approximately 30% of the global cereal consumption, and is of fundamental importance for food security. Ensuring yield increases of wheat will be sufficient to meet future needs has become an important focus in agricultural research. Powdery mildew, caused by a fungal pathogen, Blumeria graminis f. sp. triticii , is one of the most devastating diseases of common wheat worldwide. In this study, a single dominant powdery mildew resistance gene MlIW170 was identified in a wild emmer wheat species, and mapped to the distal region of chromosome arm 2B. Sequencing of a DNA region containing this resistance locus identified genes similar to resistance-like genes previously identified. Comparative analysis demonstrated that resistance gene-like sequences in this genetic locus undergo rapid evolution. Further detailed characterization of the resistance gene will provide new approaches to improve wheat's resistance against this devastating pathogen.
Technical Abstract: Wheat is one of the most important staple grain crops in the world. Powdery mildew disease caused by Blumeria graminis f.sp. tritici can result in significant losses in both grain yield and quality in wheat. In this study, the wheat powdery mildew resistance gene MlIW170 locus located on the short arm of wheat chromosome 2B, was further characterized by constructing and sequencing a BAC-based physical map contig covering a 0.3 cM genetic distance region. Additional markers were developed to delineate the resistance gene within a 0.16 cM genetic interval. Comparative analyses of this 2B region with the orthologous region from the Ae. tauschii D genome showed widespread gene colinearity, including the structural organization of both RGA-like and RPS2-like resistance genes. Comparisons to the orthologous regions from the Brachypodium and rice genomes revealed considerable dynamic evolutionary changes that have re-shaped this MlIW170 region in the wheat genome, resulting in nonsynteny for many genes, including resistance-related genes. Phylogenetic analysis of these resistance-related gene sequences indicated that the most closely related sequence of a R-like gene is usually from its orthologous copy from the homeologous genome, rather than from the paralogous copy in the same genome, suggesting the duplication of these genes in the MlIW170 region occurred before the separation of the wheat B and D genomes. These results are consistent with rapid evolution in R gene regions.