The Stripe Rust Resistance Gene Yr10 Encodes an Evolutionary-Conserved and Unique CC–NBS–LRR Sequence in Wheat

Abstract

The first seedling or all-stage resistance (R) R gene against stripe rust isolated from Moro wheat (Triticum aestivum L.) using a map-based cloning approach was identified as Yr10. Clone 4B of this gene encodes a highly evolutionary-conserved and unique CC-NBS-LRR sequence. Clone 4E, a homolog of Yr10, but lacking transcription start site (TSS) and putative TATA-box and CAAT-box, is likely a non-expressed pseudogene. Clones 4B and 4E are 84% identical and divergent in the intron and the LRR domain. Gene silencing and transgenesis were used in conjunction with inoculation with differentially avirulent and virulent stripe rust strains to demonstrate Yr10 functionality. The Yr10 CC-NBS-LRR sequence is unique among known CC-NBS-LRR R genes in wheat but highly conserved homologs (E = 0.0) were identified in Aegilops tauschii and other monocots including Hordeum vulgare and Brachypodium distachyon. Related sequences were also identified in genomic databases of maize, rice, and in sorghum. This is the first report of a CC-NBS-LRR resistance gene in plants with limited homologies in its native host, but with numerous homologous R genes in related monocots that are either host or non-hosts for stripe rust. These results represent a unique example of gene evolution and dispersion across species.

Seedling and Adult Plant Stripe Rust Resistance in Diverse Wheat–Alien Introgression Lines

“…These results are in accordance with those from other studies showing that wheat cultivars or lines that are susceptible at the seedling stage can carry high levels of APR against rust diseases (Niks et al, 2015;Singh et al, 2014). Moreover, resistance gene cloning has provided new insights for a better understanding of the functional basis of the Yr10, Yr18, and Yr36 stripe rust resistance genes (Fu et al, 2009;Krattinger et al, 2009;Liu et al, 2014). The large difference found for the number of lines having seedling susceptibility but APR in the field nurseries in Sweden (157) versus Turkey (21) may be caused by the races predominating in the respective nurseries.…”

Genome‐wide scans of selection highlight the impact of biotic and abiotic constraints in natural populations of the model grass Brachypodium distachyon

“…More specifically, we found many of well‐characterized R‐genes, i.e. genes with NBS‐LRR domains and involved in disease resistance (Mchale et al ., ; Jacob et al ., ; Liu et al ., ; Couto and Zipfel, ; Eckardt, ; Van Ooijen et al ., ), to be under ongoing or completed positive selection in the eastern population. On the other hand, we also found additional R‐genes and genes involved in phosphorylation, a process especially important for immune signaling response in plants (for review, see Park et al ., ), to be under balancing selection.…”

New insights in the battle between wheat and Puccinia striiformis

“…More than 50 stripe rust resistance genes have been documented in wheat, but only three of them have been obtained using the map-based cloning. The stripe rust resistance gene Yr10 is the first R gene cloned from wheat, encoding a CC-NBS-LRR protein and locating on chromosome 1B in Moro and originates from the Turkish line PI 178383 [73] . Lr34/Yr18 has supported resistance to rusts and powdery mildews for more than 50 years, and is now shared by wheat cultivars around the world.…”