Differential expression of the TMV resistance gene N prevents a hypersensitive response in seeds and during germination

Niemeyer, Julia; Ruhe, Jonas; Machens, Fabian; Hehl, Reinhard

doi:10.1007/s00425-012-1832-6

Cited by 4 publications

(2 citation statements)

References 33 publications

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“… 58 The N gene encodes two alternatively spliced mRNAs that possess a TIR domain, a NB domain, and a LRR, all of which are required for N function. 59 , 60 RT-qPCR analysis indicated that the N gene had a higher level of expression in ‘Su Shuai’ compared with ‘Golden Delicious’ and ‘Indo’. The MbR7 homologous gene (MDP0000233155) encodes a TIR-NBS-LRR type R protein 7.…”

Section: Discussionmentioning

confidence: 99%

Genomic variants of genes associated with three horticultural traits in apple revealed by genome re-sequencing

et al. 2014

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The apple (Malus × domestica Borkh.) cultivar ‘Su Shuai’ exhibits greater disease resistance, shorter internodes and lighter fruit flavor compared with its parents ‘Golden Delicious’ and ‘Indo’. To obtain a comprehensive overview of the sequence variation in these three horticultural traits, the genomes of ‘Su Shuai’ and ‘Indo’ were resequenced using next-generation sequencing and compared to the genome of ‘Golden Delicious’. A wide range of genetic variations were detected, including 2 454 406 and 18 749 349 single nucleotide polymorphism (SNP) and 59 547 and 50 143 structural variants (SVs) in the ‘Indo’ and ‘Su Shuai’ genomes, respectively. Among the SVs in ‘Su Shuai’, 17 genes related to disease resistance, 10 genes related to Gibberellin (GA) and 19 genes associated with fruit flavor were identified. The expression patterns of eight of the SV genes were examined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The results of this study illustrate the genomic variation in these cultivars and provide evidence for a genetic basis for the horticultural traits of disease resistance, short internodes and lighter flavor exhibited in these cultivars. These results provide a genetic basis for the phenotypic characteristics of ‘Su Shuai’ and, as such, these SVs could serve as gene-specific molecular markers in maker-assisted breeding of apples.

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Section: Discussionmentioning

confidence: 99%

Genomic variants of genes associated with three horticultural traits in apple revealed by genome re-sequencing

et al. 2014

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“…The mutation rate of the N gene in wild-type tobacco (i.e., lacking the avirulence transgene P50) was also high. Second, the N gene is not expressed during embryogenesis or in young seedlings (Niemeyer et al, 2013). In other words, no HR stress should occur at these stages of development.…”

Section: Discussion Frequent Loss Of Function Of the N Gene Is Not Caused By Stressmentioning

confidence: 99%

Unstable Allotetraploid Tobacco Genome due to Frequent Homeologous Recombination, Segmental Deletion, and Chromosome Loss

et al. 2018

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The types of mutations and their corresponding frequencies are difficult to measure in complex genomes. In this study, a high-throughput method was developed to identify spontaneous loss-of-function alleles for the resistance gene N and the transgenic avirulence gene P50 in allotetraploid tobacco. A total of 2134 loss-of-function alleles of the N gene were identified after screening 14 million F hybrids. Analysis of these mutants revealed striking evolutionary patterns for genes in polyploids. Only 14 of the loss-of-function mutations were caused by spontaneous point mutations or indels, while the others were caused by homeologous recombination (with a frequency of ∼1/12 000) or chromosome loss (∼1/15 000). Loss of the chromosome with the P50 insertion occurred at a similar frequency (∼1/13 000), and the frequency of spontaneous segmental deletion in this chromosome was ∼1/16 000. Both homeologous recombination and chromosome loss considerably decreased the viability of the mutants. Our data suggest that the high mutation rate in polyploids is probably due to the occurrence of homeologous recombination and the tolerance of large mutations such as chromosome loss in polyploid genomes. Frequent mutations tend to drive polyploids to extinction unless a novel mutation helps the polyploid to effectively compete with diploids or find a new ecological niche.

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Inducible expression of p50 from TMV for increased resistance to bacterial crown gall disease in tobacco

et al. 2013

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The dominant tobacco mosaic virus (TMV) resistance gene N induces a hypersensitive response upon TMV infection and protects tobacco against systemic spread of the virus. It has been proposed to change disease resistance specificity by reprogramming the expression of resistance genes or their corresponding avirulence genes. To reprogramme the resistance response of N towards bacterial pathogens, the helicase domain (p50) of the TMV replicase, the avirulence gene of N, was linked to synthetic promoters 4D and 2S2D harbouring elicitor-responsive cis-elements. These promoter::p50 constructs induce local necrotic lesions on NN tobacco plants in an Agrobacterium tumefaciens infiltration assay. A tobacco genotype void of N (nn) was transformed with the promoter::p50 constructs and subsequently crossed to NN plants. Nn F1 offspring selected for the T-DNA develop normally under sterile conditions. After transfer to soil, some of the F1 plants expressing the 2S2D::p50 constructs develop spontaneous necrosis. Transgenic Nn F1 plants with 4D::p50 and 2S2D::p50 expressing constructs upregulate p50 transcription and induce local necrotic lesions in an A. tumefaciens infiltration assay. When leaves and stems of Nn F1 offspring harbouring promoter::p50 constructs are infected with oncogenic A. tumefaciens C58, transgenic lines harbouring the 2S2D::p50 construct induce necrosis and completely lack tumor development. These results demonstrate a successful reprogramming of the viral N gene response against bacterial crown gall disease and highlight the importance of achieving tight regulation of avirulence gene expression and the control of necrosis in the presence of the corresponding resistance gene.

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Differential expression of the TMV resistance gene N prevents a hypersensitive response in seeds and during germination

Cited by 4 publications

References 33 publications

Genomic variants of genes associated with three horticultural traits in apple revealed by genome re-sequencing

Genomic variants of genes associated with three horticultural traits in apple revealed by genome re-sequencing

Unstable Allotetraploid Tobacco Genome due to Frequent Homeologous Recombination, Segmental Deletion, and Chromosome Loss

Inducible expression of p50 from TMV for increased resistance to bacterial crown gall disease in tobacco

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