Characterization of germline development and identification of genes associated with germline specification in pineapple

Abstract

Understanding germline specification in plants could be advantageous for agricultural applications. In recent decades, substantial efforts have been made to understand germline specification in several plant species, including Arabidopsis, rice, and maize. However, our knowledge of germline specification in many agronomically important plant species remains obscure. Here, we characterized the female germline specification and subsequent female gametophyte development in pineapple using callose staining, cytological, and whole-mount immunolocalization analyses. We also determined the male germline specification and gametophyte developmental timeline and observed male meiotic behavior using chromosome spreading assays. Furthermore, we identified 229 genes that are preferentially expressed at the megaspore mother cell (MMC) stage during ovule development and 478 genes that are preferentially expressed at the pollen mother cell (PMC) stage of anther development using comparative transcriptomic analysis. The biological functions, associated regulatory pathways and expression patterns of these genes were also analyzed. Our study provides a convenient cytological reference for exploring pineapple germline development and a molecular basis for the future functional analysis of germline specification in related plant species.

Epigenetic Regulation of Megaspore Mother Cell Formation

“…AGO104, a homolog of AGO9 in maize, is also expressed in the somatic cells surrounding the MMC, and AGO104 is required for inhibiting the transition of the germline cells to the somatic cell (Singh et al, 2011). In pineapple, many genes in the RdDM pathway are highly expressed in the MMC-stage ovule (Zhao et al, 2021). Collectively, the existence of small RNA and DNA methylation-mediated gene silencing in various plant species and the expression of the corresponding genes in the ovule primordium indicate epigenetic regulation is a widely mechanism during MMC development.…”

The genome size, chromosome number and the seed adaption to long-distance dispersal of Ipomoea pes-caprae (L.)

“…The stem apical meristems (SAMs) and the true leaves at 1 to 6 DAGs were collected and fixed in FAA (50% ethanol, 5% (v/v) acetic acid, 3.7% (v/v) formaldehyde) for at least 24 hours in the dark (Zhao et al, 2021). The fixed samples were then dehydrated gradually by treatment in sequential ethanol solutions with a gradient concentration of 30%, 50%, 70%, 80%, 90%, 95%, and 100%, and each treatment lasted 20 minutes.…”

BZR1, you have an invite: EPFL–ERECTA wants to join your female germline specification network

“…The BZR1 transcription factor family regulates over 7,000 genes ( Sun et al 2010 ). Among those is a nucleolar GTP-binding protein, Nucleostemin - like 1 ( NSN1 ), that is preferentially expressed in the pineapple ovule during the MMC stage ( Zhao et al 2021 ). To validate BZR1-mediated NSN1 expression, the authors performed chromatin immunoprecipitation and electrophoretic mobility shift assays, which showed that BZR1 binds to the E-boxes in the NSN1 promoter region.…”