Rpr1, a gene required for Rpg1-dependent resistance to stem rust in barley

Abstract

Rpg1 is a stem rust resistance gene that has protected barley from severe losses for over 60 years in the US and Canada. It confers resistance to many, but not all, pathotypes of the stem rust fungus Puccinia graminis f. sp. tritici. A fast neutron induced deletion mutant, showing susceptibility to stem rust pathotype Pgt-MCC, was identified in barley cv. Morex, which carries Rpg1. Genetic and Rpg1 mRNA and protein expression level analyses showed that the mutation was a suppressor of Rpg1 and was designated Rpr1 (Required for P. graminis resistance). Genome-wide expression profiling, using the Affymetrix Barley1 GeneChip containing approximately 22,840 probe sets, was conducted with Morex and the rpr1 mutant. Of the genes represented on the Barley1 microarray, 20 were up-regulated and 33 were down-regulated by greater than twofold in the mutant, while the Rpg1 mRNA level remained constant. Among the highly down-regulated genes (greater than fourfold), genomic PCR, RT-PCR and Southern analyses identified that three genes (Contig4901_s_at, HU03D17U_s_at, and Contig7061_s_at), were deleted in the rpr1 mutant. These three genes mapped to chromosome 4(4H) bin 5 and co-segregated with the rpr1-mediated susceptible phenotype. The loss of resistance was presumed to be due to a mutation in one or more of these genes. However, the possibility exists that there are other genes within the deletions, which are not represented on the Barley1 GeneChip. The Rpr1 gene was not required for Rpg5- and rpg4-mediated stem rust resistance, indicating that it shows specificity to the Rpg1-mediated resistance pathway.

Exploiting a fast neutron mutant genetic resource in Pisum sativum (pea) for functional genomics

“…(Bolon et al 2011), Glycine soja Siebold & Zucc. (Searle et al 2003), Hordeum vulgare L. (Zhang et al 2006), Arabidopsis thaliana (L.) Heynh. (Alonso et al 2003;Belfield et al 2012), Medicago truncatula Gaertn.…”

eQTL Regulating Transcript Levels Associated with Diverse Biological Processes in Tomato

“…Closely related plant species often have little coding sequence divergence; nonetheless, the related species often develop unique physiological, metabolic, and developmental characteristics, indicating that patterns of gene expression are important in specieslevel phenotypic variation (Kliebenstein, 2009;Koenig et al, 2013). Phenotypic differences attributed to variations in gene expression patterns have been found to influence disease resistance, insect resistance, phosphate sensing, flowering time, circadian rhythm, and plant development (Kroymann et al, 2003;Werner et al, 2005;Clark et al, 2006;Zhang et al, 2006;Svistoonoff et al, 2007;Chen et al, 2010;Hammond et al, 2011).…”

Phenotypic and Genomic Analyses of a Fast Neutron Mutant Population Resource in Soybean

“…The majority of mutations that result from FN bombardment are DNA deletions that range in size from a few base pairs to several megabases (Li et al, 2001;Men et al, 2002). Precedence exists in many species, including Arabidopsis (Arabidopsis thaliana; Alonso et al, 2003), Medicago truncatula (Oldroyd and Long, 2003), Glycine soja (Searle et al, 2003), barley (Hordeum vulgare; Zhang et al, 2006b), and Lotus japonicus (Hoffmann et al, 2007), for the use of FN mutagenesis in forward genetic screens. Many phenotype-associated genes have been successfully identified and cloned through such screens .…”