Development of novel EST-derived resistance gene markers in hop (Humulus lupulus L.)

Abstract

Although sources of resistance to major pathogens exist in cultivated hop germplasm, little effort has been invested to date in developing resistance-linked markers. The aim of this study was to design and evaluate resistance gene analogs (RGAs) potentially useful for marker-assisted selection towards novel resistant hop cultivars. A set of 34 putative hop RGAs was retrieved by screening publicly available hop expressed sequence tags (ESTs) for conserved sequence motifs of common resistance protein domains. Seventeen of these were identified as putative RGAs by BLAST analyses. Exon/intron boundary prediction enabled re-sequencing of 24 EST-RGAs, allowing the acquisition of approximately 5 kbp of novel intronic sequence and 8 kbp of re-sequenced exons. Fifteen EST-RGAs exhibited polymorphisms and were added to a framework linkage map of hop. In addition to providing ESTderived markers potentially useful for resistant hop cultivar development, this study provides valuable insights into the utility of targeting hop introns for marker development.

Broad taxonomic characterization of Verticillium wilt resistance genes reveals an ancient origin of the tomato Ve1 immune receptor

“…neomexicanus ) and is still used today as the main resistance source (Darby, ). Genetic analysis identified a single significant QTL for this resistance, suggesting that Verticillium wilt resistance in hop is conferred by more than a single gene (Jakse et al ., ; Majer et al ., ). To investigate the presence of Ve ‐like sequences in hop, Southern blotting with the tomato Ve1 gene as probe was performed, revealing low copy numbers of Ve ‐like sequences in hop cultivars (Fig.…”

Development and use of molecular markers: past and present

“…Chen et al (1998) amplified resistance gene analogues in rice, wheat and barley, and resolved the amplified products on denaturing polyacrylamide gels followed by silver staining. RGAPs can be developed based on prior sequence knowledge, or through data mining of genomic or EST databases (Majer et al, 2014). RGAP markers have been applied to gene tagging in a number of crops including wheat (Yan et al, 2003) and barley (Yan & Chen 2006).…”

Identification and Characterization of Verticillium Nonalfalfae-responsive Micrornas in the Roots of Resistant and Susceptible Hop Cultivars

“…Although there is increasing evidence that miRNAs play an important role in the regulation of gene expression during the immune response in plants, there is a scarcity of information on miRNA-mediated gene silencing during the pathogenesis of fungal diseases, such as Verticillium wilt, in various crops. In hops, a single quantitative trait loci (QTL) has been identi ed, which explains 26% of the phenotypic variance for Verticillium wilt resistance [20], and potential EST-RGA markers have been developed [21]. A well-studied example of Verticillium wilt resistance to date relates to the tomato's Ve1 gene, which codes for a leucine-rich repeat (LRR) receptor-like protein that confers the resistance to a strain of V. dahlia race 1 or V. nonalfalfae [22][23][24][25].…”