Identification of a Differentially Expressed TIR-NBS-LRR Gene in a Major QTL Associated to Leaf Rust Resistance in Salix

Abstract

An earlier identified major quantitative trait locus for resistance towards the willow leaf rust fungus Melampsora larici-epitea in a Salix viminalis x (S. viminalis × S. schwerinii) population was used to identify potential resistance genes to the rust pathogen. Screening a genomic bacterial artificial chromosome library with markers from the peak position of the QTL region revealed one gene with TIR-NBS-LRR (Toll Interleukin1 Receptor-Nucleotide Binding Site-Leucine-Rich Repeat) domain structure indicative of a resistance gene. The resistance gene analog was denoted RGA1 and further analysis revealed a number of non-synonymous single nucleotide polymorphisms in the LRR domain between the resistant and susceptible Salix genotypes. Gene expression levels under controlled conditions showed a significantly lower constitutive expression of RGA1 in the susceptible genotype. In addition, the susceptible genotype showed a significantly reduced expression level of the RGA1 gene at 24 hours post inoculation with M. larici-epitea. This indicates that the pathogen may actively suppress RGA1 gene expression allowing a compatible plant-pathogen interaction and causing infection.

Genetic Diversity and Genetic Relationships of Purple Willow (Salix purpurea L.) from Natural Locations

“…The reaction was carried out in 37 cycles (94 °C for 1 min, 42–63 °C for 2 min, depending on the primer, 72 °C for 2 min) with an initial denaturation (94 °C for 1 min) and a final elongation (72 °C for 8 min). ISSR primers were selected based on literature data [ 25 , 56 , 57 ]. The annealing temperature for every primer was determined in PCR-ISSR test reactions based on a temperature gradient ( Table S4 ).…”

“…DNA markers are valuable tools for S. purpurea studies, inter alia to identify species of Salix [ 17 , 18 , 19 ], genotypes of S. purpurea [ 20 , 21 ] and their genetic diversity [ 20 , 22 , 23 ]. They facilitate and support structural analyses of genomes, genetic mapping, identification of quantitative trait loci (QTL), marker-assisted selection (MAS) and sequencing of S. purpurea [ 24 , 25 , 26 ]. Nowadays, numerous marker systems are available and are generating from several hundred (RAPDs, ISSRs) to thousands of markers (DArTs—diversity arrays technology markers, SNPs—single nucleotide polymorphism markers).…”

Differential expression of NBS-LRR-encoding genes in the root transcriptomes of two Solanum phureja genotypes with contrasting resistance to Globodera rostochiensis

“…The second group contained 17 transcripts absent or present in small amounts in the root transcriptome of water-inoculated susceptible plants. Strong resistance to G. rostochiensis is commonly based on the rapid hypersensitive response followed by the programmed cell death of the neighboring plant cells, and it is likely that efficient NBS-LRR genes should be expressed before nematode infestation (e.g., [ 12 , 14 ]). We hypothesized that low expression of NBS-LRR receptor genes in the absence of GPCN infestation results in a delay of the hypersensitive response and may provide time for successful nematode progression.…”

“…Further comparison of their transcription patterns in resistant and susceptible genotypes revealed five candidate genes with genotype–specific expression [ 11 ]. The investigation of QTLs associated with willow resistance against leaf rust revealed a candidate TIR-NBS-LRR gene whose constitutive expression was considerably lower in the susceptible genotype before and after inoculation with Melampsora larici-epitea [ 12 ]. Comparative transcriptome analysis of Gossypium hirsutum genotypes resistant and susceptible to reniform nematodes revealed a number of candidate RGAs located close to quantitative trait loci [ 13 ].…”

A cluster of CYP6 gene family associated with the major quantitative trait locus is responsible for the pyrethroid resistance in Culex pipiens pallen

“…Quantitative trait loci (QTLs) are phenotypically defined genomic regions that contribute to allelic variation for a biological trait (Kumar et al ., ). Genes with a major effect can be experimentally mapped and characterized by establishing correlation between quantitative trait value and allelic states at linked genetic markers (Witzig et al ., ; Martin et al ., ; Nair et al ., ). Wondji et al .…”