Transcriptional Consequence and Impaired Gametogenesis with High-Grade Aneuploidy in Arabidopsis thaliana

Aneuploidy features a numerical chromosome variant that the number of chromosomes in the nucleus of a cell is not an exact multiple of the haploid number, which may have an impact on morphology and gene expression. Here we report a tertiary trisomy uncovered by characterizing a T-DNA insertion mutant (aur2-1/+) in the Arabidopsis (Arabidopsis thaliana) AURORA2 locus. Whole-genome analysis with DNA tiling arrays revealed a chromosomal translocation linked to the aur2-1 allele, which collectively accounted for a tertiary trisomy 2. Morphologic, cytogenetic and genetic analyses of aur2-1 progeny showed impaired male and female gametogenesis to various degrees and a tight association of the aur2-1 allele with the tertiary trisomy that was preferentially inherited. Transcriptome analysis showed overlapping and distinct gene expression profiles between primary and tertiary trisomy 2 plants, particularly genes involved in response to stress and various types of external and internal stimuli. Additionally, transcriptome and gene ontology analyses revealed an overrepresentation of nuclear-encoded organelle-related genes functionally involved in plastids, mitochondria and peroxisomes that were differentially expressed in at least three if not all Arabidopsis trisomics. These observations support a previous hypothesis that aneuploid cells have higher energy requirement to overcome the detrimental effects of an unbalanced genome. Moreover, our findings extend the knowledge of the complex nature of the T-DNA insertion event influencing plant genomic integrity by creating high-grade trisomy. Finally, gene expression profiling results provide useful information for future research to compare primary and tertiary trisomics for the effects of aneuploidy on plant cell physiology

Immune quiescence in the oral mucosa is maintained by a uniquely large population of highly activated Foxp3+ regulatory T cells

The oral mucosa is a critical barrier tissue that protects the oral cavity against invading pathogens and foreign antigens. Interestingly, inflammation in the oral cavity is rarely observed, indicating that overt immune activation in this site is actively suppressed. Whether Foxp3(+) Treg cells are involved in controlling immunity of the oral mucosa, however, is not fully understood. Here, we show that the oral mucosa is highly enriched in Foxp3(+) Treg cells, and that oral mucosa Treg cells are phenotypically distinct from those of LN or spleen, as they expressed copious amounts of the tissue-retention molecule CD103 and unusually high-levels of CTLA4. Acute depletion of Foxp3(+) Treg cells had catastrophic effects, resulting in marked infiltration of activated effector T cells that were associated with autoimmunity and tissue destruction of the oral mucosa. Moreover, adoptive transfer of naive CD4 T cells revealed that the oral mucosa is highly ineffective in inducing Foxp3(+) Treg cells in situ, so that it depends on recruitment and migration of exogenous Treg cells to populate this mucosal site. Collectively, these results demonstrate a previously unappreciated role and a distinct developmental pathway for Foxp3(+) Treg cells in the oral mucosa, which are essential to control local tissue immunity.Y