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Turnip mosaic virus (TuMV) is the most prevalent viral pathogen infecting most cruciferous plants. MicroRNAs (miRNAs) are around 22 nucleotides long non-protein-coding RNAs that play key regulatory roles in plants. Recent research findings show that miRNAs are involved in plant-virus interaction. However we know little about plant defense and viral offense system networks throughout microRNA regulation pathway. In this study, two small RNA libraries were constructed based on non-heading Chinese cabbage (Brassica campestris ssp. chinensis L. Makino, NHCC) leaves infected by TuMV and healthy leaves, and sequenced using the Illumina-Solexa high-throughput sequencing technology. A total of 86 conserved miRNAs belonging to 25 known miRNA families and 45 novel ones were identified. Among them, twelve conserved and ten new miRNAs were validated by real-time fluorescence quantitative PCR (qPCR). Differential expression analysis showed that 42 miRNAs were down-regulated and 27 miRNAs were up-regulated in response to TuMV stress. A total of 271 target genes were predicted using a bioinformatics approach, these genes are mainly involved in growth and resistance to various stresses. We further selected 13 miRNAs and their corresponding target genes to explore their expression pattern under TuMV and/or cold (4°C) stresses, and the results indicated that some of the identified miRNAs could link TuMV response with cold response of NHCC. The characterization of these miRNAs could contribute to a better understanding of plant-virus interaction throughout microRNA regulation pathway. This can lead to finding new approach to defend virus infection using miRNA in Chinese cabbage., (Copyright © 2015. Published by Elsevier B.V.)

Cabbage (Brassica oleracea var. capitata) is one of the most important cruciferous leafy vegetable crops and is widely cultivated all over the world. Its yield and quality are often affected by diseases such as cabbage black rot. 2R is a cabbage line that is newly resistant to black rot, which was created by radiation mutagenesis and backcross transfer. However, the underlying molecular bases and mechanisms of early-phase response of different resistant cabbage lines against black rot infections remain unknown. Here, we completed a comprehensive transcriptome profile analysis between resistant (2R) and susceptible (2T) cabbage lines after black rot inoculations. The results showed that the typical V-shaped lesions were found in inoculated plants after 15 days, and the symptoms in the susceptible cabbage lines (2T) were significant severe than that of the resistant 2R line. A total of 10,030 differentially expressed genes (DEGs) were identified, of which 384 DEGs were found to overlap in resistant and susceptible cabbage lines after black rot infections, suggesting those DEGs may play more important roles in cabbage early responses to black rot infections. We ranked the expression levels of DEGs among the four comparison sets of resistant and susceptible cabbage lines and, interestingly, found the top ten differential expression genes contained NBS-LRR genes, protein kinase genes and expansin genes. These findings provide a comprehensive differential transcriptome profile between resistant and susceptible cabbage lines and indicate some genes play key roles in the regulation of early response to black rot infections, which will help to understand the molecular resistance of cabbage against these infections. [ABSTRACT FROM AUTHOR]