Analysis of Fluorescent Reporter Activity in the Male Germline During Pollen Development by Confocal Microscopy

Targeted reprogramming of H3K27me3 resets epigenetic memory in plant paternal chromatin

Epigenetic marks are reprogrammed in the gametes to reset genomic potential in the next generation. In mammals, paternal chromatin is extensively reprogrammed through the global erasure of DNA methylation and the exchange of histones with protamines1,2. Precisely how the paternal epigenome is reprogrammed in flowering plants has remained unclear since DNA is not demethylated and histones are retained in sperm3,4. Here, we describe a multi-layered mechanism by which H3K27me3 is globally lost from histone-based sperm chromatin in Arabidopsis. This mechanism involves the silencing of H3K27me3 writers, activity of H3K27me3 erasers and deposition of a sperm-specific histone, H3.10 (ref. 5), which we show is immune to lysine 27 methylation. The loss of H3K27me3 facilitates the transcription of genes essential for spermatogenesis and pre-configures sperm with a chromatin state that forecasts gene expression in the next generation. Thus, plants have evolved a specific mechanism to simultaneously differentiate male gametes and reprogram the paternal epigenome.

Insights into the cotton anther development through association analysis of transcriptomic and small RNA sequencing

BACKGROUND

Plant anther development is a systematic and complex process precisely controlled by genes. Regulation genes and their regulatory mechanisms for this process remain elusive. In contrast to numerous researches on anther development with respect to mRNAs or miRNAs in many crops, the association analysis combining both omics has not been reported on cotton anther.

RESULTS

In this study, the molecular mechanism of cotton anther development was investigated with the employment of association analysis of transcriptome and small RNA sequencing during the predefined four stages of cotton anther development, sporogenuous cell proliferation (SCP), meiotic phase (MP), microspore release period (MRP) and pollen maturity (PM). Analysis revealed that the differentially expressed genes are increasingly recruited along with the developmental progress. Expression of functional genes differed significantly among developmental stages. The genes related with cell cycle, progesterone-mediated oocyte maturation, and meiosis are predominantly expressed at the early stage of anther development (SCP and MP), and the expression of genes involved in energy metabolism, flavonoid biosynthesis, axon guidance and phospholipase D signaling pathways is mainly enriched at the late stage of anther development (MRP and PM). Analysis of expression patterns revealed that there was the largest number of differentially expressed genes in the MP and the expression profiles of differentially expressed genes were significantly increased, which implied the importance of MP in the entire anther development cycle. In addition, prediction and analysis of miRNA targeted genes suggested that miRNAs play important roles in anther development. The miRNAs ghr-miR393, Dt_chr12_6065 and At_chr9_3080 participated in cell cycle, carbohydrate metabolism and auxin anabolism through the target genes, respectively, to achieve the regulation of anther development.

CONCLUSIONS

Through the association analysis of mRNA and miRNA, our work gives a better understanding of the preferentially expressed genes and regulation in different developmental stages of cotton anther and the importance of meiotic phase, and also the involvement of miRNAs in precise regulation for this process, which would be valuable for clarifying the mechanism of plant anther development in response to internal and external environments.