AUTHOR=Wang Shuai , Zhang Ruyang , Shi Zi , Zhao Yanxin , Su Aiguo , Wang Yuandong , Xing Jinfeng , Ge Jianrong , Li Chunhui , Wang Xiaqing , Wang Jidong , Sun Xuan , Liu Qian , Chen Yining , Zhang Yunxia , Wang Shuaishuai , Song Wei , Zhao Jiuran 

TITLE=Identification and Fine Mapping of RppM, a Southern Corn Rust Resistance Gene in Maize

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.01057

DOI=10.3389/fpls.2020.01057

ISSN=1664-462X

ABSTRACT=<p>Southern corn rust (SCR) caused by <italic>Puccinia polysora</italic> Underw. is a major disease causing severe yield losses during maize production. Here, we identified and mapped the SCR resistance gene <italic>RppM</italic> from the near-isogenic line Kangxiujing2416 (Jing2416K), which harbors <italic>RppM</italic> in the genetic background of the susceptible inbred line Jing2416. In this study, the inheritance of SCR resistance was investigated in F<sub>2</sub> and F<sub>3</sub> populations derived from a cross between Jing2416K and Jing2416. The observed 3:1 segregation ratio of resistant to susceptible plants indicated that the SCR resistance is controlled by a single dominant gene. Using an F<sub>2</sub> population, we performed bulked segregant analysis (BSA) sequencing and mapped <italic>RppM</italic> to a 3.69-Mb region on chromosome arm 10S. To further narrow down the region harboring <italic>RppM</italic>, we developed 13 insertion/deletion (InDel) markers based on the sequencing data. Finally, <italic>RppM</italic> was mapped to a region spanning 110-kb using susceptible individuals from a large F<sub>2</sub> population. Two genes (<italic>Zm00001d023265</italic> and <italic>Zm00001d023267</italic>) encoding putative CC-NBS-LRR (coiled-coiled, nucleotide-binding site, and leucine-rich repeat) proteins, a common characteristic of R genes, were located in this region (B73 RefGen_v4 reference genome). Sequencing and comparison of the two genes cloned from Jing2416K and Jing2416 revealed sequence variations in their coding regions. The relative expression levels of these two genes in Jing2416K were found to be significantly higher than those in Jing2416. <italic>Zm00001d023265</italic> and <italic>Zm00001d023267</italic> are thus potential <italic>RppM</italic> candidates.</p>