Increased experimental conditions and marker densities identified more genetic loci associated with southern and northern leaf blight resistance in maize

Authors: LI, YONG-XIANG - Chinese Academy Of Agricultural Sciences; CHEN, LI - Chinese Academy Of Agricultural Sciences; Bradbury, Peter; SHI, YUN-SU - Chinese Academy Of Agricultural Sciences; SONG, YANCHUN - Chinese Academy Of Agricultural Sciences; ZHANG, DENGFENG - Chinese Academy Of Agricultural Sciences; ZHANG, ZHIWU - Washington State University; Buckler, Edward - Ed; LI, YU - Chinese Academy Of Agricultural Sciences; WANG, TIANYU - Chinese Academy Of Agricultural Sciences

Submitted to: Nature Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2018
Publication Date: 5/1/2018
Citation: Li, Y., Chen, L., Bradbury, P., Shi, Y., Song, Y., Zhang, D., Zhang, Z., Buckler IV, E.S., Li, Y., Wang, T. 2018. Increased experimental conditions and marker densities identified more genetic loci associated with southern and northern leaf blight resistance in maize. Nature Scientific Reports. (8):6848. https://doi.org/10.1038/s41598-018-25304-z.
DOI: https://doi.org/10.1038/s41598-018-25304-z

Interpretive Summary: Southern leaf blight (SLB) and northern leaf blight (NLB) are two major foliar diseases limiting maize production worldwide. This study examines the genetic basis for resistance to these diseases in the US NAM (nested association mapping) population and a panel of 282 inbred lines representing a broad cross-section of maize backgrounds. The US NAM consists of 5000 progeny inbred lines developed from 26 parents and has been used in a wide variety of genetic studies. This study of resistance extends a previous one by adding data from locations in China and by using improved genetic markers. The large data set of observations combined with improved markers enabled researchers to identify many markers associated with resistance to both diseases and to show that three candidate genes were associated resistance in the tested locations. The identification of markers and genes conferring resistance provides a tool for maize breeders to develop varieties with improved resistance, which is important since host plant resistance is the only practical method of controlling the diseases. The study was an important collaboration between US and Chinese scientists and combined data for resistance from both countries.

Technical Abstract: Southern leaf blight (SLB) and northern leaf blight (NLB) are the two major foliar diseases limiting maize production worldwide. Upon previous study with the nested association mapping (NAM) population, which consist of 5,000 recombinant inbred lines from 25 parents crossed with B73, we expanded the phenotyping environments from the United States (US) to China, and increased the marker densities from 1106 to 7386 SNPs for linkage mapping, and from 1.6 to 28.5 million markers for association mapping. We identified 49 SLB and 48 NLB resistance-related unique QTLs in linkage mapping, and multiple loci in association mapping with candidate genes involved in known plant disease-resistance pathways. Furthermore, an independent natural population with 282 diversified inbred lines were sequenced for four candidate genes selected based on their biological functions. Three of them demonstrated significant associations with disease resistance. These findings provided valuable resources for further implementations to develop varieties with superior resistance for NLB and SLB.