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Title: Intercellular communication in Arabidopsis thaliana pollen discovered via AHG3 transcript movement from the vegetative cell to sperm

item JIANG, HUA - Uppsala University
item YI, JUN - Uppsala University
item BOAVIDA, LEONARD - Gulbenkian Institute
item CHEN, YUAN - University Of California
item BECKER, JORG - Gulbenkian Institute
item KOHLER, CLAUDIA - Uppsala University
item McCormick, Sheila

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: In pollen grains, the known function of the vegetative cell is to extend a pollen tube to transport the two sperm cells to the embryo sac for fertilization. Because the vegetative cell is much larger and more metabolically active than sperm, it has been assumed that the vegetative cell also might supply various components to sperm, but there was no direct evidence to support this hypothesis. We used deletion and promoter exchange constructs to provide direct evidence that the vegetative cell provides protein-encoding transcripts to sperm cells, highlighting a previously unidentified role of the vegetative cell.

Technical Abstract: An Arabidopsis pollen grain (male gametophyte) consists of three cells: the vegetative cell, which forms the pollen tube, and two sperm cells enclosed within the vegetative cell. It is still unclear if there is intercellular communication between the vegetative cell and the sperm cells. Here we show that ABA-hypersensitive germination3 (AHG3), encoding a protein phosphatase, is specifically transcribed in the vegetative cell but predominantly translated in sperm cells. We used a series of deletion constructs and promoter exchanges to document transport of AHG3 transcripts from the vegetative cell to sperm and showed that their transport requires sequences in both the 5' UTR and the coding region. Thus, in addition its known role in transporting sperm during pollen tube growth, the vegetative cell also contributes transcripts to the sperm cells.