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TIR-NBS-LRR (TNL) genes greatly affect plant growth and development. Ninety TNL-type genes were identified and characterized in Chinese cabbage ( Brassica rapa ssp . pekinensis ). Tissue-expression profiling revealed different expression levels in different tissues. qRT-PCR analysis revealed the expression patterns of 69 genes challenged by Turnip mosaic virus (TuMV): 42 genes were up-regulated, and 11 genes down-regulated; genes were grouped according to their different expression patterns. Sixteen candidate genes were identified as responding to TuMV infection. This study supplies information on resistance genes involved in Chinese cabbage's response against TuMV, and furthers the understanding of resistance mechanisms in B. rapa crops. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Previous evidence suggested the Turnip mosaic virus viral ribonuclear protein complex, comprising the viral RNA, moved to the plasmodesmata via the secretory pathway. We performed a global analysis of gene expression in Brassica rapa and identified a complex array of changes affecting pathogen response. Thirty-eight secretory pathway genes were identified. The quantitative real-time polymerase chain reaction results were consistent with microarray analysis. Combined with previous studies, we speculated that the secretory pathway participates in viral replication and movement. Exploring the precise function of the genes identified in this analysis will offer new insights into viral defense in B. rapa . [ABSTRACT FROM AUTHOR]