Tomato is the second most important vegetable crop worldwide (), and breeding for disease resistance is a major goal. This class was previously grouped into sub-classes based on sequence similarity with the canonical CNLs that contain an EDVID amino-acid motif, and the RPW8-like proteins whose N-termini resemble the coiled-coil structure of the Arabidopsis RPW8 protein. The non-TIR class (CNLs) is less well defined, but some members of this class contain helical coiled-coil–like (CC) sequences in their amino-terminal domain. The TIR class of plant NB-LRR proteins (TNLs) contains a Toll, interleukin 1 receptor, R protein homology (TIR) protein-protein interaction domain at the amino terminus. Plant NB-LRR proteins (also called NLR, NBS-LRR or NB-ARC-LRR proteins) are typically categorized into the TIR or non-TIR class, based on the identity of the sequences that precede the NB domain, as well as motifs within this domain. These intracellular immune receptors, termed R (resistance) genes, encode proteins that resemble mammal NOD-like receptors and typically carry a nucleotide binding and leucine-rich repeat domains (NB-LRR). This mechanism is called ‘effector-triggered immunity’ (ETI). Plants in turn possess a second line of defence, which is represented by proteins that detect specific effector molecules or their effects on host cell components. Adapted pathogens have evolved mechanisms to overcome PAMP-triggered immunity (PTI) by suppressing the immune signalling using “effector molecules”. The first line of detection resides at the cell surface and involves recognition of pathogen-associated molecular patterns (PAMPs) through cell surface transmembrane receptors. Defence activation requires pathogen detection, which can occur outside or inside the plant cell, by one of two known distinct recognition mechanisms. To control pathogens, plants activate defence mechanisms that can culminate in a hypersensitive response (HR) in infected and adjacent cells. cDNA RenSeq enables for the first time next-gen sequencing approaches targeted to this very low-expressed gene family without the need for normalization. The reannotated tomato NB-LRR complements, phylogenetic relationships and chromosomal locations provided in this paper will provide breeders and scientists with a useful tool to identify novel disease resistance traits. RenSeq is a promising method to facilitate analysis of plant resistance gene complements. Use of RenSeq on cDNA from uninfected and late blight-infected tomato leaves allows the avoidance of sequence analysis of non-expressed paralogues. A phylogenetic comparison to the Arabidopsis thaliana NB-LRR complement verifies the high conservation of the more ancient CC RPW8-type NB-LRRs. Phylogenetic analyses show a high conservation of all NB-LRR classes between Heinz 1706, LA1589 and the potato clone DM, suggesting that all sub-families were already present in the last common ancestor. The majority of these are however fragmented, with 5′- and 3′-end located on the edges of separate contigs. pimpinellifolium LA1589 genome, RenSeq enabled the annotation of 355 NB-LRR genes. Reannotation included the splitting of gene models, combination of partial genes to a longer sequence and closing of assembly gaps. Using 250-bp MiSeq reads after RenSeq on genomic DNA of Heinz 1706, we identified 105 novel NB-LRR sequences. Here, we established RenSeq on the reference genome of tomato ( Solanum lycopersicum) Heinz 1706, using 260 previously identified NB-LRR genes in an updated Solanaceae RenSeq bait library. Recently, we developed the RenSeq method to reannotate the full NB-LRR gene complement in potato and to identify novel sequences that were not picked up by the automated gene prediction software. The availability of draft crop plant genomes allows the prediction of the full complement of genes that encode NB-LRR resistance gene homologs, enabling a more targeted breeding for disease resistance.
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