Pyramiding rpg4- and Rpg1-Mediated Stem Rust Resistance in Barley Requires the Rrr1 Gene for Both to Function

作者：Roshan Sharma Poudel, Abdullah Fahad Alhashel, Thomas P. Gross, Patrick Gross, Robert Saxon Brueggeman · 发表于：Frontiers in Plant Science · 年份：2018 · DOI：10.3389/fpls.2018.01789 · 被引用次数：35 · 研究领域：Wheat and Barley Genetics and Pathology、Bioenergy crop production and management、Plant-Microbe Interactions and Immunity

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt) is an economically important disease of wheat and barley. Rpg1 is the only resistance gene deployed in Midwestern US barley varieties and provides remarkable resistance to most North American races, except Pgt race QCCJB. Rpg1 is also ineffective against Pgt race TTKSK and its lineage that originated in Africa. The barley rpg4-mediated resistance locus (RMRL) conferring resistance to Pgt races QCCJB and TTKSK was isolated from line Q21861, which is resistant to all known Pgt races due to Rpg1 and RMRL. To develop elite barley varieties RMRL was pyramided into the varieties, Pinnacle and Conlon (both contain Rpg1), producing the near isogenic lines (NILs), Pinnacle RMRL-NIL (PRN) and Conlon RMRL-NIL (CRN). The CRN was resistant to Pgt races QCCJB (RMRL specific) and HKHJC (Rpg1 specific) at the seedling stage and Pgt race TTKSK (RMRL specific) at the adult stage. In contrast, PRN was susceptible to QCCJB and HKHJC at the seedling stage and TTKSK at the adult stage. Interestingly, PRN’s susceptibility to QCCJB and HKHJC showed that RMRL was non functional in the Pinnacle background but its presence also suppressed Rpg1-mediated resistance. Thus, in the absence of a gene/s found in the Q21861 background, Rpg1 becomes non functional if RMRL is present, suggesting that another polymorphic gene, that we designated Rrr1 (required for rpg4-mediated resistance 1), is required for RMRL resistance and Rpg1-mediated resistance i...