Stem rust resistance in wheat is suppressed by a subunit of the mediator complex

Abstract

Stem rust is an important disease of wheat that can be controlled using resistance genes. The gene SuSr-D1 identified in cultivar 'Canthatch' suppresses stem rust resistance. SuSr-D1 mutants are resistant to several races of stem rust that are virulent on wild-type plants. Here we identify SuSr-D1 by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of stem rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation in med15b.D mutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to stem rust. Suppression is a common phenomenon and this study provides novel insight into suppression of rust resistance in wheat.

CREB-binding protein gene,HAC701, negatively regulates WRKY45-dependent immunity in rice

“…It could be that disruption of HAC701-dependent pathways through HAC701 mutation led to activation of WRKY45-dependent pathways in an already SA-potentiated rice network, although this needs to be further examined in detail. Our results are also consistent with the disease phenotype presented by non-sense mutation in Med15 gene, a subunit of Mediator complex (55). The med15b.D wheat mutants were resistant to stem rust, and the authors attribute a part of this to segmental coregulation in which a certain portion of the chromosome containing R genes (i.e.…”

Functional Analysis of OsMED16 and OsMED25 in Response to Biotic and Abiotic Stresses in Rice

“…The mutants med14 and med15 decreased the resistance to Pst DC3000 in Arabidopsis ( Canet et al, 2012 ; Zhang et al, 2013 ). In wheat, the MED15 mutant suppressed the resistance to stem rust ( Hiebert et al, 2020 ). However, in Arabidopsis , med16 mutants displayed decreased resistance to Pst DC3000/avrRpt2, Pst DC3000, A. brassicicola , B. cinerea , and Sclerotinia sclerotiorum ( S. sclerotiorum ) ( Wathugala et al, 2012 ; Zhang et al, 2012 ; Wang et al, 2015 ).…”

Editorial: Fungal Wheat Diseases: Etiology, Breeding, and Integrated Management

“…The pyramidization of major and minor genes could lead to a higher level and more durable resistance (Singh et al, 2014 ). But testing the effective function of each gene in this stack is essential as these genes can interfere with each other (Hurni et al, 2014 ) or reduce effectiveness in a certain genetic background (Hiebert et al, 2020 ). The Avr effectors can be used as probes to confirm the function of R genes in the absence of the pathogen (Vleeshouwers and Oliver, 2014 ).…”