Independent parental contributions initiate zygote polarization inArabidopsis thaliana

Abstract

Embryogenesis of flowering plants is initiated by polarization of the zygote, a prerequisite for correct axis formation in the embryo. Zygote polarity and the decision between embryonic and non-embryonic development in the daughter cells is controlled by a MITOGEN-ACTIVATING PROTEIN (MAP) kinase signaling pathway including the MAPKK kinase YODA (YDA). Upstream of YDA act two members of the BRASINOSTEROID SIGNALING KINASE (BSK) family, BSK1 and BSK2. These membrane-associated proteins serve as signaling relay linking receptor kinase complexes with intracellular signaling cascades. The receptor kinases acting upstream of BSK1 and BSK2 in the zygote, however, have so far not been identified. Instead, YDA can in part be activated by the non-canonical BSK family member SHORT SUSPENSOR (SSP) that is contributed by the sperm cell during fertilization. Here, we show that the receptor kinase ERECTA plays a crucial role in zygote polarization as maternally contributed part of the embryonic YDA pathway. SSP on the other hand provides an independent, paternal input to YDA activation, outlining a Y-shaped pathway. We conclude that two independent parental contributions initiate zygote polarization and control suspensor formation and embryonic development.

Novel insights into water-deficit-responsive mRNAs and lncRNAs during fiber development in Gossypium hirsutum

“…As sequence variation induced target and mechanism variation, the function of members in miR482 family differ possibly from each other [ 78 , 82 ]. RH42 (DEAD-box ATP-dependent RNA helicase 42, Gh_A10G1972) plays an essential role in DNA and RNA metabolism such as transcription, replication and repair [ 83 ]; ERECTA (LRR receptor-like serine/threonine-protein kinase, Gh_A07G2348 and Gh_D07G0162) has been shown to regulate plant flowering and transpiration efficiency in part via effects on epidermal cell expansion, cell-cell communication, and stomatal density [ 84 , 85 ]. Gh_D06G2174 with a DUF616 domain (protein of unknown function) has not been described and annotated in the genomic database of G. hirsutum .…”

Receptor-like protein kinases in plant reproduction: Current understanding and future perspectives

“… ER/ERL1/2 LRR XIII-RLK BSK1/2 zygote polarization suspensor development Neu et al. (2019) and Wang et al. (2021) / / / SSP zygote polarization suspensor development Bayer et al.…”

“…Very recently, ERf receptor kinases were found to act as maternal factors upstream of BSK1/2 to activate the YDA-dependent signaling during zygotic polarization. Therefore, the paternally initiated SSP and maternal ERf-BSK signal converge at YDA to control zygote elongation and asymmetric division ( Wang et al., 2021 ). It is already known that ERf-mediated ligand signaling of EPFLs regulates inflorescence development and stomata patterning through the YDA-mediated MAPK cascade ( Lee et al., 2012 ; Uchida et al., 2012 ; Meng et al., 2012 , 2015 ).…”

“…The specificities of these two ER signaling pathways are at least partially guaranteed by specifically expressed downstream transcription factors SPL and WOX8. SPL is phosphorylated and thus stabilized by MPK3/6 during anther lobe initiation, whereas WOX8 expression is regulated by MPK3/6 during embryogenesis ( Hord et al., 2008 ; Ueda et al., 2017 ; Zhao et al., 2017 ; Wang et al., 2021 ). Actually, differential expression of some key signaling factors, not only the downstream transcription factors but also the ligands, receptors, co-receptors, and other members, at different developmental stages or in distinct tissues or organs possibly provides another key to ensure signaling specificities.…”