Identification of microRNA targets in tomato fruit development using high-throughput sequencing and degradome analysis.
ABSTRACT MicroRNAs (miRNAs) play important roles in plant development through regulation of gene expression by mRNA degradation or translational inhibition. Despite the fact that tomato (Solanum lycopersicum) is the model system for studying fleshy fruit development and ripening, only a few experimentally proven miRNA targets are known, and the role of miRNA action in these processes remains largely unknown. Here, by using parallel analysis of RNA ends (PARE) for global identification of miRNA targets and comparing four different stages of tomato fruit development, a total of 119 target genes of miRNAs were identified. Of these, 106 appeared to be new targets. A large part of the identified targets (56) coded for transcription factors. Auxin response factors, as well as two known ripening regulators, COLORLESS NON-RIPENING (CNR) and APETALA2a (SlAP2a), with developmentally regulated degradation patterns were identified. The levels of the intact messenger of both CNR and AP2a are actively modulated during ripening, by miR156/157 and miR172, respectively. Additionally, two TAS3-mRNA loci were identified as targets of miR390. Other targets such as ARGONAUTE 1 (AGO1), shown to be involved in miRNA biogenesis in other plant species, were identified, which suggests a feedback loop regulation of this process. In this study, it is shown that miRNA-guided cleavage of mRNAs is likely to play an important role in tomato fruit development and ripening.
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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.PLoS Pathogens 10/2014; 10(10):e1004464. · 8.14 Impact Factor
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ABSTRACT: MicroRNAs (miRNAs) are a class of small, endogenous RNAs that take part in regulating genes through mediating gene expressions at the post-transcriptional level in plants. Previous studies have reported miRNA identification in various plants ranging from model plants to perennial fruit trees. However, the role of miRNAs in pear (Pyrus bretschneideri) fruit development is not clear. Here, we investigated the miRNA profiles of pear fruits from different time stages during development with Illumina HiSeq 2000 platform and bioinformatics analysis. Quantitative real-time PCR was used to validate the expression levels of miRNAs.BMC Genomics 11/2014; 15(1):953. · 4.04 Impact Factor
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ABSTRACT: In plants, microRNAs (miRNAs) regulate gene expression mainly at the post-transcriptional level. Previous studies have demonstrated that miRNA-mediated gene silencing pathways play vital roles in plant development. Here, we used a high-throughput sequencing approach to characterize the miRNAs and their targeted transcripts in the leaf, flower and fruit of sweet orange.BMC genomics. 08/2014; 15(1):695.