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1.
Development ; 149(22)2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36305487

RESUMO

During flowering plant reproduction, anthers produce pollen grains, the development of which is supported by the tapetum, a nourishing maternal tissue that also contributes non-cell-autonomously to the pollen wall, the resistant external layer on the pollen surface. How the anther restricts movement of the tapetum-derived pollen wall components, while allowing metabolites such as sugars and amino acids to reach the developing pollen, remains unknown. Here, we show experimentally that in arabidopsis thaliana the tapetum and developing pollen are symplastically isolated from each other, and from other sporophytic tissues, from meiosis onwards. We show that the peritapetal strip, an apoplastic structure, separates the tapetum and the pollen grains from other anther cell layers and can prevent the apoplastic diffusion of fluorescent proteins, again from meiosis onwards. The formation and selective barrier functions of the peritapetal strip require two NADPH oxidases, RBOHE and RBOHC, which play a key role in pollen formation. Our results suggest that, together with symplastic isolation, gating of the apoplast around the tapetum may help generate metabolically distinct anther compartments.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Flores , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Pólen/metabolismo , Reprodução , Regulação da Expressão Gênica de Plantas
2.
Proc Natl Acad Sci U S A ; 119(22): e2201446119, 2022 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-35609199

RESUMO

The surface of pollen grains is reinforced by pollen wall components produced noncell autonomously by tapetum cells that surround developing pollen within the male floral organ, the anther. Here, we show that tapetum activity is regulated by the GASSHO (GSO) receptor-like kinase pathway, controlled by two sulfated peptides, CASPARIAN STRIP INTEGRITY FACTOR 3 (CIF3) and CIF4, the precursors of which are expressed in the tapetum itself. Coordination of tapetum activity with pollen grain development depends on the action of subtilases, including AtSBT5.4, which are produced stage specifically by developing pollen grains. Tapetum-derived CIF precursors are processed by subtilases, triggering GSO-dependent tapetum activation. We show that the GSO receptors act from the middle layer, a tissue surrounding the tapetum and developing pollen. Three concentrically organized cell types, therefore, cooperate to coordinate pollen wall deposition through a multilateral molecular dialogue.


Assuntos
Flores , Pólen , Regulação da Expressão Gênica de Plantas , Peptídeos/metabolismo , Pólen/metabolismo
3.
PLoS Genet ; 15(4): e1007847, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30998684

RESUMO

The embryonic cuticle is necessary for normal seed development and seedling establishment in Arabidopsis. Although mutants with defective embryonic cuticles have been identified, neither the deposition of cuticle material, nor its regulation, has been described during embryogenesis. Here we use electron microscopy, cuticle staining and permeability assays to show that cuticle deposition initiates de novo in patches on globular embryos. By combining these techniques with genetics and gene expression analysis, we show that successful patch coalescence to form a continuous cuticle requires a signalling involving the endosperm-specific subtilisin protease ALE1 and the receptor kinases GSO1 and GSO2, which are expressed in the developing embryonic epidermis. Transcriptome analysis shows that this pathway regulates stress-related gene expression in seeds. Consistent with these findings we show genetically, and through activity analysis, that the stress-associated MPK6 protein acts downstream of GSO1 and GSO2 in the developing embryo. We propose that a stress-related signalling pathway has been hijacked in some angiosperm seeds through the recruitment of endosperm-specific components. Our work reveals the presence of an inter-compartmental dialogue between the endosperm and embryo that ensures the formation of an intact and functional cuticle around the developing embryo through an "auto-immune" type interaction.


Assuntos
Arabidopsis/embriologia , Arabidopsis/fisiologia , Desenvolvimento Embrionário , Desenvolvimento Vegetal , Transdução de Sinais , Estresse Fisiológico , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Desenvolvimento Embrionário/genética , Endosperma/embriologia , Endosperma/genética , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fenótipo , Desenvolvimento Vegetal/genética , Plantas Geneticamente Modificadas , Sementes/genética , Estresse Fisiológico/genética , Transgenes
4.
J Cell Sci ; 122(Pt 1): 25-35, 2009 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-19050045

RESUMO

Phosphoinositides have emerged as key regulators of membrane traffic through their control of the localization and activity of several effector proteins. Both Rab5 and phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P(2)] are involved in the early steps of the clathrin-dependent endocytic pathway, but little is known about how their functions are coordinated. We have studied the role of PtdIns(4,5)P(2) and Rab5 in the Drosophila germline during oogenesis. We found that Rab5 is required for the maturation of early endocytic vesicles. We show that PtdIns(4,5)P(2) is required for endocytic-vesicle formation, for Rab5 recruitment to endosomes and, consistently, for endocytosis. Furthermore, we reveal a previously undescribed role of Rab5 in releasing PtdIns(4,5)P(2), PtdIns(4,5)P(2)-binding budding factors and F-actin from early endocytic vesicles. Finally, we show that overexpressing the PtdIns(4,5)P(2)-synthesizing enzyme Skittles leads to an endocytic defect that is similar to that seen in rab5 loss-of-function mutants. Hence, our results argue strongly in favor of the hypothesis that the Rab5-dependant release of PtdIns(4,5)P(2) from endosomes that we discovered in this study is crucial for endocytosis to proceed.


Assuntos
Drosophila melanogaster/fisiologia , Endocitose/fisiologia , Células Germinativas/metabolismo , Fosfatidilinositol 4,5-Difosfato/metabolismo , Proteínas rab5 de Ligação ao GTP/metabolismo , Animais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Endossomos/metabolismo , Células Germinativas/citologia , Oócitos/fisiologia , Oócitos/ultraestrutura , Oogênese/fisiologia , Interferência de RNA , Vesículas Transportadoras/metabolismo , Proteínas rab5 de Ligação ao GTP/genética
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