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J Exp Bot. 2015 Apr;66(7):1833-43. doi: 10.1093/jxb/eru524. Epub 2015 Jan 8.

The FRK1 mitogen-activated protein kinase kinase kinase (MAPKKK) from Solanum chacoense is involved in embryo sac and pollen development.

Author information

1
Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada.
2
Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada Institut de recherche en biotechnologie, Conseil national de recherches du Canada, 6100 Avenue Royalmount, Montréal, QC H4P 2R2, Canada.
3
Institut de recherche en biotechnologie, Conseil national de recherches du Canada, 6100 Avenue Royalmount, Montréal, QC H4P 2R2, Canada.
4
Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC H1X 2B2, Canada dp.matton@umontreal.ca.

Abstract

The fertilization-related kinase 1 (ScFRK1), a nuclear-localized mitogen-activated protein kinase kinase kinase (MAPKKK) from the wild potato species Solanum chacoense, belongs to a small group of pMEKKs that do not possess an extended N- or C-terminal regulatory domain. Initially selected based on its highly specific expression profile following fertilization, in situ expression analyses revealed that the ScFRK1 gene is also expressed early on during female gametophyte development in the integument and megaspore mother cell and, later, in the synergid and egg cells of the embryo sac. ScFRK1 mRNAs are also detected in pollen mother cells. Transgenic plants with lower or barely detectable levels of ScFRK1 mRNAs lead to the production of small fruits with severely reduced seed set, resulting from a concomitant decline in the number of normal embryo sacs produced. Megagametogenesis and microgametogenesis were affected, as megaspores did not progress beyond the functional megaspore (FG1) stage and the microspore collapsed around the first pollen mitosis. As for other mutants that affect embryo sac development, pollen tube guidance was severely affected in the ScFRK1 transgenic lines. Gametophyte to sporophyte communication was also affected, as observed from a marked change in the transcriptomic profiles of the sporophytic tissues of the ovule. The ScFRK1 MAPKKK is thus involved in a signalling cascade that regulates both male and female gamete development.

KEYWORDS:

Embryo sac development; MAPKKK; Solanaceae.; gametophyte to sporophyte communication; megagametogenesis; microgametogenesis; pollen tube guidance; seed and fruit development

PMID:
25576576
PMCID:
PMC4378624
DOI:
10.1093/jxb/eru524
[Indexed for MEDLINE]
Free PMC Article

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