Abstract
In plants, the cell fates of a vegetative cell (VC) and generative cell (GC) are determined after the asymmetric division of the haploid microspore. The VC exits the cell cycle and grows a pollen tube, while the GC undergoes further mitosis to produce two sperm cells for double fertilization. However, our understanding of the mechanisms underlying their fate differentiation remains limited. One major advantage of the nuclear proteome analysis is that it is the only method currently able to uncover the systemic differences between VC and GC due to GC being engulfed within the cytoplasm of VC, limiting the use of transcriptome. Here, we obtained pure preparations of the vegetative cell nuclei (VNs) and generative cell nuclei (GNs) from germinating lily pollens. Utilizing these high-purity VNs and GNs, we compared the differential nucleoproteins between them using state-of-the-art quantitative proteomic techniques. We identified 720 different amount proteins (DAPs) and grouped the results in 11 fate differentiation categories. Among them, we identified 29 transcription factors (TFs) and 10 cell fate determinants. Significant differences were found in the molecular activities of vegetative and reproductive nuclei. The TFs in VN mainly participate in pollen tube development. In comparison, the TFs in GN are mainly involved in cell differentiation and male gametogenesis. The identified novel TFs may play an important role in cell fate differentiation. Our data also indicate differences in nuclear pore complexes and epigenetic modifications: more nucleoporins synthesized in VN; more histone variants and chaperones; and structural maintenance of chromosome (SMC) proteins, chromatin remodelers, and DNA methylation-related proteins expressed in GN. The VC has active macromolecular metabolism and mRNA processing, while GC has active nucleic acid metabolism and translation. Moreover, the members of unfolded protein response (UPR) and programmed cell death accumulate in VN, and DNA damage repair is active in GN. Differences in the stress response of DAPs in VN vs. GN were also found. This study provides a further understanding of pollen cell differentiation mechanisms and also a sound basis for future studies of the molecular mechanisms behind cell fate differentiation.
Highlights
The plant male gametophyte development begins with a diploid microspore mother cell differentiation, which produces haploid gametes through meiosis and mitosis
vegetative cell nucleus (VN) were isolated from just germinated pollen using 7% Percoll density centrifugation, while generative cell nucleus (GN) were acquired from purified generative cell (GC), which are released from bursting of vegetative cell (VC) and purified using 18%/24% Percoll density centrifugation
In VN, different amount proteins (DAPs) are mainly involved in Reproductive Structure Development, Organelle Organization, Stress Response, and Metabolism, while in GN, DAPs mainly participated in biological processes including Chromosome Organization, Cell Cycle, Methylation, Epigenetic Regulation, and Metabolism
Summary
The plant male gametophyte (pollen) development begins with a diploid microspore mother cell differentiation, which produces haploid gametes through meiosis and mitosis. This process involves a series of cell fate determination and differentiation (Borg et al, 2009). A key event in pollen development is the asymmetric division of the post-meiotic haploid microspore resulting in two distinct fate daughter cells, vegetative cell (VC) and generative cell (GC) (Rutley and Twell, 2015). Once the mature pollens land on the stigma, the germinated pollen tube would deliver the two SCs to the ovule for double fertilization (Berger and Twell, 2011; Yang et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
