Cellular Pathways Regulating Responses to Compatible and Self-Incompatible Pollen in Brassica and Arabidopsis Stigmas Intersect at Exo70A1, a Putative Component of the Exocyst Complex
Marcus A. Samuel,Yolanda T. Chong,Katrina E. Haasen,May Grace Aldea-Brydges,Sophia L. Stone,Daphne R. Goring +5 more
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TLDR
The data show that the Exo70A1 protein functions at the intersection of two cellular pathways, where it is required in the stigma for the acceptance of compatible pollen in both Brassica and Arabidopsis and is negatively regulated by Brassica self-incompatibility.Abstract:
In the Brassicaceae, compatible pollen–pistil interactions result in pollen adhesion to the stigma, while pollen grains from unrelated plant species are largely ignored. There can also be an additional layer of recognition to prevent self-fertilization, the self-incompatibility response, whereby self pollen grains are distinguished from nonself pollen grains and rejected. This pathway is activated in the stigma and involves the ARM repeat–containing 1 (ARC1) protein, an E3 ubiquitin ligase. In a screen for ARC1-interacting proteins, we have identified Brassica napus Exo70A1, a putative component of the exocyst complex that is known to regulate polarized secretion. We show through transgenic studies that loss of Exo70A1 in Brassica and Arabidopsis thaliana stigmas leads to the rejection of compatible pollen at the same stage as the self-incompatibility response. A red fluorescent protein:Exo70A1 fusion rescues this stigmatic defect in Arabidopsis and is found to be mobilized to the plasma membrane concomitant with flowers opening. By contrast, increased expression of Exo70A1 in self-incompatible Brassica partially overcomes the self pollen rejection response. Thus, our data show that the Exo70A1 protein functions at the intersection of two cellular pathways, where it is required in the stigma for the acceptance of compatible pollen in both Brassica and Arabidopsis and is negatively regulated by Brassica self-incompatibility.read more
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Male-female crosstalk during pollen germination, tube growth and guidance, and double fertilization.
TL;DR: This review focuses on intercellular communication between the pollen grain/pollen tube including the sperm cells with the various sporophytic maternal tissues and the cells of the female gametophyte.
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EXPO, an Exocyst-Positive Organelle Distinct from Multivesicular Endosomes and Autophagosomes, Mediates Cytosol to Cell Wall Exocytosis in Arabidopsis and Tobacco Cells
Juan Wang,Yu Ding,Junqi Wang,Stefan Hillmer,Yansong Miao,Sze Wan Lo,Xiangfeng Wang,David Robinson,Liwen Jiang +8 more
TL;DR: An unconventional secretory pathway involving a double-membrane exocyst-positive organelle that mediates exocytosis directly from the cytosol to cell wall is described, which represents a form of unconventional secretion unique to plants.
Journal ArticleDOI
The Ubiquitin Ligase PUB22 Targets a Subunit of the Exocyst Complex Required for PAMP-Triggered Responses in Arabidopsis
Martin Stegmann,Martin Stegmann,Ryan G. Anderson,Kazuya Ichimura,Tamara Pečenková,Patrick Reuter,Viktor Žárský,John M. McDowell,Ken Shirasu,Marco Trujillo +9 more
TL;DR: It is shown that Exo70B2 is required for both immediate and later responses triggered by all tested PAMPs, suggestive of a role in signaling, and proposed mechanism by which PUB22-mediated degradation of Exo 70B2 contributes to the attenuation of PAMP-induced signaling.
Journal ArticleDOI
The Arabidopsis Exocyst Complex Is Involved in Cytokinesis and Cell Plate Maturation
Matyáš Fendrych,Lukáš Synek,Tamara Pečenková,Tamara Pečenková,Hana Toupalová,Rex A. Cole,Edita Janková Drdová,Jana Nebesářová,Miroslava Šedinová,Michal Hála,John E. Fowler,Viktor Žárský,Viktor Žárský +12 more
TL;DR: It is concluded that the exocyst complex is involved in secretory processes during cytokinesis in Arabidopsis cells, notably in cell plate initiation, cell plate maturation, and formation of new primary cell wall.
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