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MicroRNAs suppress NB domain genes in tomato that confer resistance to Fusarium oxysporum.

Ouyang S, Park G, Atamian HS, Han CS, Stajich JE, Kaloshian I, Borkovich KA - PLoS Pathog. (2014)

Bottom Line: One slmiR5300 target corresponds to tm-2, a susceptible allele of the Tomato Mosaic Virus resistance gene, supporting functions in immunity to a fungal pathogen.The observation that none of the targets correspond to I-2, the only known resistance (R) gene for F. oxysporum in tomato, supports roles for additional R genes in the immune response.Taken together, our findings suggest that Moneymaker is highly susceptible because its potential resistance is insufficiently expressed due to the action of miRNAs.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology and Microbiology, Institute for Integrative Genome Biology, University of California, Riverside, Riverside, California, United States of America.

ABSTRACT
MicroRNAs (miRNAs) suppress the transcriptional and post-transcriptional expression of genes in plants. Several miRNA families target genes encoding nucleotide-binding site-leucine-rich repeat (NB-LRR) plant innate immune receptors. The fungus Fusarium oxysporum f. sp. lycopersici causes vascular wilt disease in tomato. We explored a role for miRNAs in tomato defense against F. oxysporum using comparative miRNA profiling of susceptible (Moneymaker) and resistant (Motelle) tomato cultivars. slmiR482f and slmiR5300 were repressed during infection of Motelle with F. oxysporum. Two predicted mRNA targets each of slmiR482f and slmiR5300 exhibited increased expression in Motelle and the ability of these four targets to be regulated by the miRNAs was confirmed by co-expression in Nicotiana benthamiana. Silencing of the targets in the resistant Motelle cultivar revealed a role in fungal resistance for all four genes. All four targets encode proteins with full or partial nucleotide-binding (NB) domains. One slmiR5300 target corresponds to tm-2, a susceptible allele of the Tomato Mosaic Virus resistance gene, supporting functions in immunity to a fungal pathogen. The observation that none of the targets correspond to I-2, the only known resistance (R) gene for F. oxysporum in tomato, supports roles for additional R genes in the immune response. Taken together, our findings suggest that Moneymaker is highly susceptible because its potential resistance is insufficiently expressed due to the action of miRNAs.

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Determination of mRNA levels for control genes and predicted targets in tomato cultivars using qRT-PCR.Total tomato root RNA was used for qRT-PCR with gene-specific primers. Errors are expressed as the standard error. * and *** indicate significant differences when compared to the corresponding control plants in the same treatments at p<0.05 and p<0.001, respectively. A. Transcript levels of Mi-1, I-2 and four I-2 homologs. Motelle and Moneymaker have different alleles of Mi-1[89], while Moneymaker appears to lack I-2. The prefix “Mot” signifies that the indicated I-2 homolog has been previously identified in Motelle [28], while “Sol” indicates that the homolog was found during BLAST searches of the Sol database. B. Expression of the four predicted target genes. Solyc08g075630 and Solyc08g076000 are predicted targets of slmiR482f, while Solyc05g008650 and Solyc08g018220 are predicted targets of slmiR5300.
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ppat-1004464-g004: Determination of mRNA levels for control genes and predicted targets in tomato cultivars using qRT-PCR.Total tomato root RNA was used for qRT-PCR with gene-specific primers. Errors are expressed as the standard error. * and *** indicate significant differences when compared to the corresponding control plants in the same treatments at p<0.05 and p<0.001, respectively. A. Transcript levels of Mi-1, I-2 and four I-2 homologs. Motelle and Moneymaker have different alleles of Mi-1[89], while Moneymaker appears to lack I-2. The prefix “Mot” signifies that the indicated I-2 homolog has been previously identified in Motelle [28], while “Sol” indicates that the homolog was found during BLAST searches of the Sol database. B. Expression of the four predicted target genes. Solyc08g075630 and Solyc08g076000 are predicted targets of slmiR482f, while Solyc05g008650 and Solyc08g018220 are predicted targets of slmiR5300.

Mentions: We next tested the possibility that the presence of slmiR482f or slmiR5300 would suppress expression of the target genes, leading to reduced levels of the encoded mRNAs and proteins. Before quantitating expression of putative target mRNAs, we first determined the expression levels of several control genes in our four RNA preparations using qRT-PCR (Fig. 4A). These included I-2, required for F. oxysporum resistance [29], several I-2-homologous genes identified in the Sol Genomics database, and Mi-1, required for resistance to nematodes and other pests, but not F. oxysporum. Mi-1 was chosen because Motelle and Moneymaker are also near-isogenic for this gene [30]. The results for I-2 and Mi-1 were in agreement with previous findings and the genotypes of the two cultivars [30]. I-2 was not detectable in Moneymaker, but levels increased more than 3-fold in Motelle after infection with F. oxysporum. Mi-1 levels were similar in both cultivars and did not change significantly after F. oxysporum treatment. Expression of the four I-2-homologous genes varied, but none exhibited a significant difference between water control and F. oxysporum exposure.


MicroRNAs suppress NB domain genes in tomato that confer resistance to Fusarium oxysporum.

Ouyang S, Park G, Atamian HS, Han CS, Stajich JE, Kaloshian I, Borkovich KA - PLoS Pathog. (2014)

Determination of mRNA levels for control genes and predicted targets in tomato cultivars using qRT-PCR.Total tomato root RNA was used for qRT-PCR with gene-specific primers. Errors are expressed as the standard error. * and *** indicate significant differences when compared to the corresponding control plants in the same treatments at p<0.05 and p<0.001, respectively. A. Transcript levels of Mi-1, I-2 and four I-2 homologs. Motelle and Moneymaker have different alleles of Mi-1[89], while Moneymaker appears to lack I-2. The prefix “Mot” signifies that the indicated I-2 homolog has been previously identified in Motelle [28], while “Sol” indicates that the homolog was found during BLAST searches of the Sol database. B. Expression of the four predicted target genes. Solyc08g075630 and Solyc08g076000 are predicted targets of slmiR482f, while Solyc05g008650 and Solyc08g018220 are predicted targets of slmiR5300.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4199772&req=5

ppat-1004464-g004: Determination of mRNA levels for control genes and predicted targets in tomato cultivars using qRT-PCR.Total tomato root RNA was used for qRT-PCR with gene-specific primers. Errors are expressed as the standard error. * and *** indicate significant differences when compared to the corresponding control plants in the same treatments at p<0.05 and p<0.001, respectively. A. Transcript levels of Mi-1, I-2 and four I-2 homologs. Motelle and Moneymaker have different alleles of Mi-1[89], while Moneymaker appears to lack I-2. The prefix “Mot” signifies that the indicated I-2 homolog has been previously identified in Motelle [28], while “Sol” indicates that the homolog was found during BLAST searches of the Sol database. B. Expression of the four predicted target genes. Solyc08g075630 and Solyc08g076000 are predicted targets of slmiR482f, while Solyc05g008650 and Solyc08g018220 are predicted targets of slmiR5300.
Mentions: We next tested the possibility that the presence of slmiR482f or slmiR5300 would suppress expression of the target genes, leading to reduced levels of the encoded mRNAs and proteins. Before quantitating expression of putative target mRNAs, we first determined the expression levels of several control genes in our four RNA preparations using qRT-PCR (Fig. 4A). These included I-2, required for F. oxysporum resistance [29], several I-2-homologous genes identified in the Sol Genomics database, and Mi-1, required for resistance to nematodes and other pests, but not F. oxysporum. Mi-1 was chosen because Motelle and Moneymaker are also near-isogenic for this gene [30]. The results for I-2 and Mi-1 were in agreement with previous findings and the genotypes of the two cultivars [30]. I-2 was not detectable in Moneymaker, but levels increased more than 3-fold in Motelle after infection with F. oxysporum. Mi-1 levels were similar in both cultivars and did not change significantly after F. oxysporum treatment. Expression of the four I-2-homologous genes varied, but none exhibited a significant difference between water control and F. oxysporum exposure.

Bottom Line: One slmiR5300 target corresponds to tm-2, a susceptible allele of the Tomato Mosaic Virus resistance gene, supporting functions in immunity to a fungal pathogen.The observation that none of the targets correspond to I-2, the only known resistance (R) gene for F. oxysporum in tomato, supports roles for additional R genes in the immune response.Taken together, our findings suggest that Moneymaker is highly susceptible because its potential resistance is insufficiently expressed due to the action of miRNAs.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology and Microbiology, Institute for Integrative Genome Biology, University of California, Riverside, Riverside, California, United States of America.

ABSTRACT
MicroRNAs (miRNAs) suppress the transcriptional and post-transcriptional expression of genes in plants. Several miRNA families target genes encoding nucleotide-binding site-leucine-rich repeat (NB-LRR) plant innate immune receptors. The fungus Fusarium oxysporum f. sp. lycopersici causes vascular wilt disease in tomato. We explored a role for miRNAs in tomato defense against F. oxysporum using comparative miRNA profiling of susceptible (Moneymaker) and resistant (Motelle) tomato cultivars. slmiR482f and slmiR5300 were repressed during infection of Motelle with F. oxysporum. Two predicted mRNA targets each of slmiR482f and slmiR5300 exhibited increased expression in Motelle and the ability of these four targets to be regulated by the miRNAs was confirmed by co-expression in Nicotiana benthamiana. Silencing of the targets in the resistant Motelle cultivar revealed a role in fungal resistance for all four genes. All four targets encode proteins with full or partial nucleotide-binding (NB) domains. One slmiR5300 target corresponds to tm-2, a susceptible allele of the Tomato Mosaic Virus resistance gene, supporting functions in immunity to a fungal pathogen. The observation that none of the targets correspond to I-2, the only known resistance (R) gene for F. oxysporum in tomato, supports roles for additional R genes in the immune response. Taken together, our findings suggest that Moneymaker is highly susceptible because its potential resistance is insufficiently expressed due to the action of miRNAs.

Show MeSH
Related in: MedlinePlus