Identification of DNA methylated regions by using methylated DNA immunoprecipitation sequencing in Brassica rapa

DNA methylation is an epigenetic gene regulatory mechanism that plays an essential role in gene expression, transposon silencing, genome imprinting and plant development. We investigated the influence of DNA methylation on gene expression in Brassica rapa L., to understand whether epigenetic differences exist between inbred lines. Genome-wide DNA methylation was analysed by methylated DNA immunoprecipitation sequencing (MeDIP-seq) of 14-day-old first and second leaves from two inbred lines of Chinese cabbage, one susceptible and one resistant to fusarium yellows caused by Fusarium oxysporum f. sp. conglutinans. MACS (model-based analysis for ChIP-seq) identified DNA methylation peaks in genic regions including 2 kb upstream, exon, intron and 2 kb downstream. More than 65% of genes showed similar patterns of DNA methylation in the genic regions in the two inbred lines. DNA methylation states of the two inbred lines were compared with their transcriptome. Genes having DNA methylation in the intron and in the 200 bp upstream and downstream regions were associated with a lower expression level in both lines. A small number of genes showed a negative correlation between differences in DNA methylation levels and differences in transcriptional levels in the two inbred lines, suggesting that DNA methylation in these genes results in transcriptional suppression

The role of FRIGIDA and FLOWERING LOCUS C genes in flowering time of Brassica rapa leafy vegetables

© 2019, The Author(s). There is a wide variation of flowering time among lines of Brassica rapa L. Most B. rapa leafy (Chinese cabbage etc.) or root (turnip) vegetables require prolonged cold exposure for flowering, known as vernalization. Premature bolting caused by low temperature leads to a reduction in the yield/quality of these B. rapa vegetables. Therefore, high bolting resistance is an important breeding trait, and understanding the molecular mechanism of vernalization is necessary to achieve this goal. In this study, we demonstrated that BrFRIb functions as an activator of BrFLC in B. rapa. We showed a positive correlation between the steady state expression levels of the sum of the BrFLC paralogs and the days to flowering after four weeks of cold treatment, suggesting that this is an indicator of the vernalization requirement. We indicate that BrFLCs are repressed by the accumulation of H3K27me3 and that the spreading of H3K27me3 promotes stable FLC repression. However, there was no clear relationship between the level of H3K27me3 in the BrFLC and the vernalization requirement. We also showed that if there was a high vernalization requirement, the rate of repression of BrFLC1 expression following prolonged cold treatments was lower

Related polymorphic F-box protein genes between haplotypes clustering in the BAC contig sequences around the S-RNase of Japanese pear

Most fruit trees in the Rosaceae exhibit self-incompatibility, which is controlled by the pistil S gene, encoding a ribonuclease (S-RNase), and the pollen S gene at the S-locus. The pollen S in Prunus is an F-box protein gene (SLF/SFB) located near the S-RNase, but it has not been identified in Pyrus and Malus. In the Japanese pear, various F-box protein genes (PpSFBB-α–γ) linked to the S-RNase are proposed as the pollen S candidate. Two bacterial artificial chromosome (BAC) contigs around the S-RNase genes of Japanese pear were constructed, and 649 kb around S4-RNase and 378 kb around S2-RNase were sequenced. Six and 10 pollen-specific F-box protein genes (designated as PpSFBB4-u1–u4, 4-d1–d2 and PpSFBB2-u1–u5, 2-d1–d5, respectively) were found, but PpSFBB4-α–γ and PpSFBB2-γ were absent. The PpSFBB4 genes showed 66.2–93.1% amino acid identity with the PpSFBB2 genes, which indicated clustering of related polymorphic F-box protein genes between haplotypes near the S-RNase of the Japanese pear. Phylogenetic analysis classified 36 F-box protein genes of Pyrus and Malus into two major groups (I and II), and also generated gene pairs of PpSFBB genes and PpSFBB/Malus F-box protein genes. Group I consisted of gene pairs with 76.3–94.9% identity, while group II consisted of gene pairs with higher identities (>92%) than group I. This grouping suggests that less polymorphic PpSFBB genes in group II are non-S pollen genes and that the pollen S candidates are included in the group I PpSFBB genes

Transcriptional Association between mRNAs and Their Paired Natural Antisense Transcripts Following <i>Fusarium oxysporum</i> Inoculation in <i>Brassica rapa</i> L.

Long noncoding RNAs (lncRNAs) play important roles in abiotic and biotic stress responses; however, studies on the mechanism of regulation of lncRNA expression are limited in plants. The present study examined the relationship between lncRNA expression level and two active histone modifications (H3K4me3 and H3K36me3) in Brassica rapa. Both histone marks were enriched in the chromatin regions encoding lncRNAs, especially around the transcription start site. The transcription level of long intergenic noncoding RNAs was positively associated with the level of H3K4me3 and H3K36me3, while this association was not observed in natural antisense RNAs (NATs) and intronic noncoding RNAs. As coordinate expression of mRNAs and paired NATs under biotic stress treatment has been identified, the transcriptional relationship between mRNAs and their paired NATs following Fusarium oxysporum f. sp. conglutinans (Foc) inoculation was examined. A positive association of expression levels between mRNAs and their paired NATs following Foc inoculation was observed. This association held for several defense-response-related genes and their NAT pairs. These results suggest that coordinate expression of mRNAs and paired NATs plays a role in the defense response against Foc

Quantum duels and truels

A truel, or three person generalization of a duel, is a popular model in game theory of a struggle for survival. The outcome is often sensitive to the precise rules under which the truel is performed and can be anti-intuitive. We propose a quantum scheme, along the lines of recent work in quantum game theory, for the problems of duels and truels. Interference amongst the players' strategies can arise, leading to game equilibria different from the classical case