One of the devastating diseases that threaten the world's wheat production is yellow rust, caused by Puccinia striiformis f. sp. tritici (Pst). Approximately 88 percent of wheat production is susceptible to yellow rust and estimates say that the disease ruins at least five million tons of the global annual wheat harvest.

A large international group of researchers zoomed in on the gene sequence of the Yr15 resistance gene in wheat. Yr15 is a broad-spectrum R-gene derived from wild emmer wheat and is known for being one of the most effective resistance genes against yellow rust due to its unique mode of action. The international group of researchers mapped the gene sequence of Yr15 and investigated how the resistance gene prevents fungal growth inside the infected wheat plant.

According to Professor Mogens Støvring Hovmøller from the Department of Agroecology at Aarhus University, Yr15 works differently than other resistance genes. They have discovered that Yr15 produces defense responses early in the infection process, and there is only one single case where the fungus could bypass this defense.

For more details, read the news release or download the open access paper in Nature Communications.

Fungal development in Pst-infected Avocet S and Avocet+Yr15 NILs during 14 days post inoculation (dpi). a–c Pst haustorium (H) within invaded plant host cell observed in Avocet+Yr15 at 3 dpi under bright field (a) and fluorescence (b), connected to HMC via neckband (NB; c). Bars=20µm (a, b), 5µm (c). d Comparative amounts of fungal biomass (chitin) within leaf tissues of NILs during 1–14 dpi. Error bars denote standard deviation (s.d.) based on eight biological replicates. e Fluorescence micrographs of fungal colonies and feeding structures at 1, 7, and 14 dpi in susceptible and resistant NILs. Bars=100 μm. f Leaf segments at 1, 7, and 14 dpi in susceptible and resistant NILs. The black lines delineate a 1cm segment in the middle of the second leaf of the same plant. g Fungal structures and host responses in Avocet+Yr15 at 4 and 8 dpi. The fungal colony (in green) consist of a substomatal vesicle (SSV) and primary infection hyphae (PH) with haustorial mother cells (HMC). Indicative signs of host cell autofluorescence (AF) are visible already at 4 dpi, while at 8 dpi the infected host cells show bright orange AF and appear to be collapsed and distorted; a couple of them contain aggregated chloroplasts (CP) with bright fluorescence as an indicator of host HR. Bars=40µm.