Background: The myeloblastosis (MYB) superfamily is the largest transcription factor family in plants that play diverse roles during stress responses. However, the biotic stress-responsive MYB transcription factors of the grapevine have not been systematically studied. In China, grapevine berries are often infected with the grapevine berry inner necrosis virus (GINV), which eventually reduces the nutritional quality and commodity value. Results: The present study identified and characterized 265 VvMYB or VvMYB-related genes of the “Crimson seedless” grapevine. Based on DNA-binding domain analysis, these VvMYB proteins were classified into four subfamilies, including MYB-related, 2R-MYB, 3R-MYB, and 4R-MYB. Phylogenetic analysis divided the MYB transcription factors into 26 subgroups. Overexpression of VvMYB58 suppressed GINV abundance in the grapevine. Further qPCR indicated that among 41 randomly selected VvMYB genes, 12 were induced during GINV infection, while 28 were downregulated. These findings suggest that VvMYB genes actively regulate defense response in the grapevine. Conclusion: A deeper understanding of the MYB TFs engaged in GINV defense response will help devise better management strategies. The present study also provides a foundation for further research on the functions of the MYB transcription factors.

Xinyang Maojian (XYMJ) tea is one of the world’s most popular green teas; the development of new sprouts directly affects the yield and quality of tea products, especially for XYMJ, which has hairy tips. Here, we used transcriptome and small RNA sequencing to identify mRNAs and miRNAs, respectively, involved in regulating leaf development in different plant tissues (bud, leaf, and stem). We identified a total of 381 conserved miRNAs. Given that no genomic data for XYMJ green tea are available, we compared the sequencing data for XYMJ green tea with genomic data from a closely related species (Tieguanyin) and the Camellia sinensis var. sinensis database; we identified a total of 506 and 485 novel miRNAs, respectively. We also identified 11 sequence-identical novel miRNAs in the tissues of XYMJ tea plants. Correlation analyses revealed 97 miRNA–mRNA pairs involved in leaf growth and development; the csn-miR319-2/csnTCP2 and miR159–csnMYB modules were found to be involved in leaf development in XYMJ green tea. Quantitative real-time PCR was used to validate the expression levels of the miRNAs and mRNAs. The miRNAs and target genes identified in this study might shed new light on the molecular mechanisms underlying the regulation of leaf development in tea plants.

Citrus fruits produced in China are often affected by granulation. Granulation is an altered physiological state of citrus fruits occurring usually before harvest but whose underlying mechanisms remain elusive. In this study, cDNA-AFLP technology enabled the identification of 116 granulation-associated genes in pummelo (C. grandis) juice sacs. Differentially expressed transcript-derived fragments (TDFs) were shown to be mainly involved in biological regulation and signal transduction, carbohydrate and energy metabolism, nucleic acid, protein metabolism, stress responses, and cell metabolism. Therefore, granulation in pummelo juice sacs seems to involve the following alterations: (1) changes in hormone levels; (2) activation of metabolic pathways related to ATP and sugar synthesis to produce more energy; (3) nucleic acid accumulation and increased protein degradation; (4) activation of stress-responsive metabolic pathways; (5) accelerated juice sac senescence. Our findings provide an overview of differential responses occurring at the transcriptional level in granulated juice sacs, thus revealing new insights into the adaptive mechanisms underlying this altered physiological state in 'Guanximiyou' pummelo (C. grandis) juice sacs.