1
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Macgregor SR, Beronilla PKS, Goring DR. The Arabidopsis SNARE complex genes regulate the early stages of pollen-stigma interactions. PLANT REPRODUCTION 2024; 37:309-320. [PMID: 38038738 DOI: 10.1007/s00497-023-00488-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 10/22/2023] [Indexed: 12/02/2023]
Abstract
KEY MESSAGE The VAMP721, VAMP722, SYP121, SYP122 and SNAP33 SNAREs are required in the Arabidopsis stigma for pollen hydration, further supporting a role for vesicle trafficking in the stigma's pollen responses. In the Brassicaceae, the process of accepting compatible pollen is a key step in successful reproduction and highly regulated following interactions between the pollen and the stigma. Central to this is the initiation of secretion in the stigma, which is proposed to provide resources to the pollen for hydration and germination and pollen tube growth. Previously, the eight exocyst subunit genes were shown to be required in the Arabidopsis stigma to support these pollen responses. One of the roles of the exocyst is to tether secretory vesicles at the plasma membrane for membrane fusion by the SNARE complex to enable vesicle cargo release. Here, we investigate the role of Arabidopsis SNARE genes in the stigma for pollen responses. Using a combination of different knockout and knockdown SNARE mutant lines, we show that VAMP721, VAMP722, SYP121, SYP122 and SNAP33 are involved in this process. Significant disruptions in pollen hydration were observed following pollination of wildtype pollen on the mutant SNARE stigmas. Overall, these results place the Arabidopsis SNARE complex as a contributor in the stigma for pollen responses and reaffirm the significance of secretion in the stigma to support the pollen-stigma interactions.
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Affiliation(s)
- Stuart R Macgregor
- Department of Cell & Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada
- Faculty of Science, York University, Toronto, Canada
| | - Paula K S Beronilla
- Department of Cell & Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada
| | - Daphne R Goring
- Department of Cell & Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada.
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, M5S 3B2, Canada.
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2
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Guo L, Huang Z, Chen X, Yang M, Yang M, Liu Z, Han X, Ma X, Wang X, Gao Q. SD-RLK28 positively regulates pollen hydration on stigmas as a PCP-Bβ receptor in Arabidopsis thaliana. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:2395-2406. [PMID: 37485903 DOI: 10.1111/jipb.13547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 07/24/2023] [Indexed: 07/25/2023]
Abstract
Pollen hydration on dry stigmas is strictly regulated by pollen-stigma interactions in Brassicaceae. Although several related molecular events have been described, the molecular mechanism underlying pollen hydration remains elusive. Multiple B-class pollen coat proteins (PCP-Bs) are involved in pollen hydration. Here, by analyzing the interactions of two PCP-Bs with three Arabidopsis thaliana stigmas strongly expressing S-domain receptor kinase (SD-RLK), we determined that SD-RLK28 directly interacts with PCP-Bβ. We investigated pollen hydration, pollen germination, pollen tube growth, and stigma receptivity in the sd-rlk28 and pcp-bβ mutants. PCP-Bβ acts in the pollen to regulate pollen hydration on stigmas. Loss of SD-RLK28 had no effect on pollen viability, and sd-rlk28 plants had normal life cycles without obvious defects. However, pollen hydration on sd-rlk28 stigmas was impaired and pollen tube growth in sd-rlk28 pistils was delayed. The defect in pollen hydration on sd-rlk28 stigmas was independent of changes in reactive oxygen species levels in stigmas. These results indicate that SD-RLK28 functions in the stigma as a PCP-Bβ receptor to positively regulate pollen hydration on dry stigmas.
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Affiliation(s)
- Li Guo
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Ziya Huang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xingyu Chen
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Min Yang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Miaomiao Yang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Ziwei Liu
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xuejie Han
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xiangjie Ma
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xiaoli Wang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Qiguo Gao
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
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3
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Riglet L, Fobis-Loisy I. Cytoskeleton Remodeling in Arabidopsis Stigmatic Cells Following Pollination. Methods Mol Biol 2023; 2604:215-225. [PMID: 36773236 DOI: 10.1007/978-1-0716-2867-6_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
In plants, the first interaction that occurs between the male gametophytes (pollen grains) and the stigmatic epidermis of the female organ is crucial for successful reproduction. The stigma consists of a dome of flask-shaped cells specialized in pollen capture. In these stigmatic cells, the cytoskeleton network (cortical microtubules and actin microfilaments) actively responds to pollen contact and undergoes dynamic remodeling required for successful pollen acceptance to occur. Here, we have designed several microscopy mountings to monitor stigmatic cytoskeleton dynamics. These designs are based on the constraints linked to the tightly regulated pollen-stigma interaction and depend upon the experimental goal, either a static view or live-cell imaging.
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Affiliation(s)
- Lucie Riglet
- The Sainsbury Laboratory, Bateman Street, CB2 1LR, University of Cambridge, Cambridge, UK
| | - Isabelle Fobis-Loisy
- Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, CNRS, INRAE, Lyon, France.
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4
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Dahake A, Jain P, Vogt CC, Kandalaft W, Stroock AD, Raguso RA. A signal-like role for floral humidity in a nocturnal pollination system. Nat Commun 2022; 13:7773. [PMID: 36522313 PMCID: PMC9755274 DOI: 10.1038/s41467-022-35353-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
Previous studies have considered floral humidity to be an inadvertent consequence of nectar evaporation, which could be exploited as a cue by nectar-seeking pollinators. By contrast, our interdisciplinary study of a night-blooming flower, Datura wrightii, and its hawkmoth pollinator, Manduca sexta, reveals that floral relative humidity acts as a mutually beneficial signal in this system. The distinction between cue- and signal-based functions is illustrated by three experimental findings. First, floral humidity gradients in Datura are nearly ten-fold greater than those reported for other species, and result from active (stomatal conductance) rather than passive (nectar evaporation) processes. These humidity gradients are sustained in the face of wind and are reconstituted within seconds of moth visitation, implying substantial physiological costs to these desert plants. Second, the water balance costs in Datura are compensated through increased visitation by Manduca moths, with concomitant increases in pollen export. We show that moths are innately attracted to humid flowers, even when floral humidity and nectar rewards are experimentally decoupled. Moreover, moths can track minute changes in humidity via antennal hygrosensory sensilla but fail to do so when these sensilla are experimentally occluded. Third, their preference for humid flowers benefits hawkmoths by reducing the energetic costs of flower handling during nectar foraging. Taken together, these findings suggest that floral humidity may function as a signal mediating the final stages of floral choice by hawkmoths, complementing the attractive functions of visual and olfactory signals beyond the floral threshold in this nocturnal plant-pollinator system.
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Affiliation(s)
- Ajinkya Dahake
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA.
| | - Piyush Jain
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Caleb C Vogt
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
| | - William Kandalaft
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
| | - Abraham D Stroock
- Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
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5
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Abhinandan K, Sankaranarayanan S, Macgregor S, Goring DR, Samuel MA. Cell-cell signaling during the Brassicaceae self-incompatibility response. TRENDS IN PLANT SCIENCE 2022; 27:472-487. [PMID: 34848142 DOI: 10.1016/j.tplants.2021.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 10/15/2021] [Accepted: 10/26/2021] [Indexed: 06/13/2023]
Abstract
Self-incompatibility (SI) is a mechanism that many plant families employ to prevent self-fertilization. In the Brassicaceae, the S-haplotype-specific interaction of the pollen-borne ligand, and a stigma-specific receptor protein kinase triggers a signaling cascade that culminates in the rejection of self-pollen. While the upstream molecular components at the receptor level of the signaling pathway have been extensively studied, the intracellular responses beyond receptor activation were not as well understood. Recent research has uncovered several key molecules and signaling events that operate in concert for the manifestation of the self-incompatible responses in Brassicaceae stigmas. Here, we review the recent discoveries in both the compatible and self-incompatible pathways and provide new perspectives on the early stages of Brassicaceae pollen-pistil interactions.
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Affiliation(s)
- Kumar Abhinandan
- University of Calgary, Department of Biological Sciences, Calgary, Alberta T2N 1N4, Canada; 20/20 Seed Labs Inc., Nisku, Alberta T9E 7N5, Canada
| | | | - Stuart Macgregor
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
| | - Daphne R Goring
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
| | - Marcus A Samuel
- University of Calgary, Department of Biological Sciences, Calgary, Alberta T2N 1N4, Canada.
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6
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Macgregor SR, Lee HK, Nelles H, Johnson DC, Zhang T, Ma C, Goring DR. Autophagy is required for self-incompatible pollen rejection in two transgenic Arabidopsis thaliana accessions. PLANT PHYSIOLOGY 2022; 188:2073-2084. [PMID: 35078230 PMCID: PMC8969033 DOI: 10.1093/plphys/kiac026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 12/22/2021] [Indexed: 05/16/2023]
Abstract
Successful reproduction in the Brassicaceae is mediated by a complex series of interactions between the pollen and the pistil, and some species have an additional layer of regulation with the self-incompatibility trait. While the initial activation of the self-incompatibility pathway by the pollen S-locus protein 11/S locus cysteine-rich protein and the stigma S Receptor Kinase is well characterized, the downstream mechanisms causing self-pollen rejection are still not fully understood. In previous studies, we detected the presence of autophagic bodies with self-incompatible (SI) pollinations in Arabidopsis lyrata and transgenic Arabidopsis thaliana lines, but whether autophagy was essential for self-pollen rejection was unknown. Here, we investigated the requirement of autophagy in this response by crossing mutations in the essential AUTOPHAGY7 (ATG7) and ATG5 genes into two different transgenic SI A. thaliana lines in the Col-0 and C24 accessions. By using these previously characterized transgenic lines that express A. lyrata and Arabidopsis halleri self-incompatibility genes, we demonstrated that disrupting autophagy weakened their SI responses in the stigma. When the atg7 or atg5 mutations were present, an increased number of SI pollen was found to hydrate and form pollen tubes that successfully fertilized the SI pistils. Additionally, we confirmed the presence of GFP-ATG8a-labeled autophagosomes in the stigmatic papillae following SI pollinations. Together, these findings support the requirement of autophagy in the self-incompatibility response and add to the growing understanding of the intracellular mechanisms employed in the transgenic A. thaliana stigmas to reject self-pollen.
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Affiliation(s)
- Stuart R Macgregor
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada M5S 3B2
| | | | - Hayley Nelles
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada M5S 3B2
| | - Daniel C Johnson
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada M5S 3B2
| | - Tong Zhang
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
| | - Chaozhi Ma
- National Key Laboratory of Crop Genetic Improvement, National Center of Rapeseed Improvement in Wuhan, Huazhong Agricultural University, Wuhan 430070, China
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7
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Sui J, Jia W, Xin Y, Zhang Y. Transcriptomics-Based Identification of Genes Related to Tapetum Degradation and Microspore Development in Lily. Genes (Basel) 2022; 13:genes13020366. [PMID: 35205410 PMCID: PMC8872214 DOI: 10.3390/genes13020366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/07/2022] [Accepted: 02/12/2022] [Indexed: 12/04/2022] Open
Abstract
Lily is a popular and economically ornamental crop around the world. However, its high production of pollen grains causes serious problems to consumers, including allergies and staining of clothes. During anther development, the tapetum is a crucial step for pollen formation and microspore release. Therefore, it is important to understand the mechanism of tapetum degradation and microspore development in lily where free pollen contamination occurs. Here, we used the cut lily cultivar ‘Siberia’ to characterize the process of tapetum degradation through the use of cytology and transcriptomic methods. The cytological observation indicated that, as the lily buds developed from 4 cm (Lo 4 cm) to 8 cm (Lo 8 cm), the tapetum completed the degradation process and the microspores matured. Furthermore, by comparing the transcriptome profiling among three developmental stages (Lo 4 cm, Lo 6 cm and Lo 8 cm), we identified 27 differentially expressed genes. These 27 genes were classed into 4 groups by function, namely, cell division and expansion, cell-wall morphogenesis, transcription factors, LRR-RLK (leucine-rich repeat receptor-like kinases), plant hormone biosynthesis and transduction. Quantitative real-time PCR was performed as validation of the transcriptome data. These selected genes are candidate genes for the tapetum degradation and microspore development of lily and our work provides a theoretical basis for breeding new lily cultivars without pollen.
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Affiliation(s)
- Juanjuan Sui
- Department of Biology, Biology and Food Engineering College, Fuyang Normal University, Fuyang 236037, China;
| | - Wenjie Jia
- Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University, Beijing 100193, China; (W.J.); (Y.X.)
- Flower Research Institute, Yunnan Academy of Agricultural Sciences, Kunming 650205, China
| | - Yin Xin
- Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University, Beijing 100193, China; (W.J.); (Y.X.)
| | - Yuanyuan Zhang
- College of Biological Sciences, China Agricultural University, Beijing 100193, China
- Correspondence:
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8
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Kim MJ, Jeon BW, Oh E, Seo PJ, Kim J. Peptide Signaling during Plant Reproduction. TRENDS IN PLANT SCIENCE 2021; 26:822-835. [PMID: 33715959 DOI: 10.1016/j.tplants.2021.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 02/02/2021] [Accepted: 02/17/2021] [Indexed: 05/08/2023]
Abstract
Plant signaling peptides are involved in cell-cell communication networks and coordinate a wide range of plant growth and developmental processes. Signaling peptides generally bind to receptor-like kinases, inducing their dimerization with co-receptors for signaling activation to trigger cellular signaling and biological responses. Fertilization is an important life event in flowering plants, involving precise control of cell-cell communications between male and female tissues. Peptide-receptor-like kinase-mediated signaling plays an important role in male-female interactions for successful fertilization in flowering plants. Here, we describe the recent findings on the functions and signaling pathways of peptides and receptors involved in plant reproduction processes including pollen germination, pollen tube growth, pollen tube guidance to the embryo sac, and sperm cell reception in female tissues.
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Affiliation(s)
- Min-Jung Kim
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, Korea; Department of Integrative Food, Bioscience, and Technology, Chonnam National University, Gwangju 61186, Korea
| | - Byeong Wook Jeon
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, Korea; Department of Integrative Food, Bioscience, and Technology, Chonnam National University, Gwangju 61186, Korea
| | - Eunkyoo Oh
- Department of Life Sciences, Korea University, Seoul 02841, Korea
| | - Pil Joon Seo
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Jungmook Kim
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, Korea; Department of Integrative Food, Bioscience, and Technology, Chonnam National University, Gwangju 61186, Korea; Kumho Life Science Laboratory, Chonnam National University, Buk-Gu, Gwangju 61186, Korea.
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9
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Cabada Gomez DA, Chavez MI, Cobos AN, Gross RJ, Yescas JA, Balogh MA, Indriolo E. COPI complex isoforms are required for the early acceptance of compatible pollen grains in Arabidopsis thaliana. PLANT REPRODUCTION 2020; 33:97-110. [PMID: 32277349 DOI: 10.1007/s00497-020-00387-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/11/2020] [Indexed: 05/04/2023]
Abstract
The Coat Protein I (COPI) complex is a seven-subunit coatomer complex consisting of the α, β, β', γ, δ, ε, and ζ proteins. In Arabidopsis thaliana, COPI is required for retrograde transport from the Golgi to the endoplasmic reticulum, Golgi maintenance, and cell plate formation. During compatible pollination, vesicle recruitment to the pollen contact point is required for pollen hydration and pollen tube penetration. Here, to identify other aspects of trafficking involved in the acceptance of compatible pollen by stigmatic papillae and to determine their roles in compatible pollination, we characterized knockout lines of several isoforms of the COPI complex, including α1-COP, γ-COP, and ε-COP. Specifically, we characterized pollen grain adherence, pollen tube penetration, and seed set in the mutants. Of the mutant lines examined, α1-cop had the most severe phenotypes, including altered compatible pollen grain adherence and tube germination and reduced seed set, whereas the other lines had milder phenotypes but visibly retarded compatible pollen acceptance. This is the first study demonstrating that COPI complex subunits are required for the acceptance of compatible pollen.
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Affiliation(s)
- Daniel A Cabada Gomez
- Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM, 88003, USA
- PULSe Graduate Program, Purdue University, 155 S. Grant St., West Lafayette, IN, 47907, USA
| | - M Isabella Chavez
- Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM, 88003, USA
- Cochlear Americas, 13059 East Peakview Ave, Centennial, CO, 80111, USA
| | - Alejandra N Cobos
- Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM, 88003, USA
| | - Roni J Gross
- Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM, 88003, USA
| | - Julia A Yescas
- Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM, 88003, USA
| | - Michael A Balogh
- Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM, 88003, USA
| | - Emily Indriolo
- Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM, 88003, USA.
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10
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Lee HK, Macgregor S, Goring DR. A Toolkit for Teasing Apart the Early Stages of Pollen-Stigma Interactions in Arabidopsis thaliana. Methods Mol Biol 2020; 2160:13-28. [PMID: 32529426 DOI: 10.1007/978-1-0716-0672-8_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In hermaphroditic flowering plants, the female pistil serves as the main gatekeeper of mate acceptance as several mechanisms are present to prevent fertilization by unsuitable pollen. The characteristic Brassicaceae dry stigma at the top of pistil represents the first layer that requires pollen recognition to elicit appropriate physiological responses from the pistil. Successful pollen-stigma interactions then lead to pollen hydration, pollen germination, and pollen tube entry into the stigmatic surface. To assess these early stages in detail, our lab has used three experimental procedures to quantitatively and qualitatively characterize the outcome of compatible pollen-stigma interactions that would ultimately lead to the successful fertilization. These assays are also useful for assessing self-incompatible pollinations and mutations that affect these pathways. The model organism, Arabidopsis thaliana, offers an excellent platform for these investigations as loss-of-function or gain-of-function mutants can be easily generated using CRISPR/Cas9 technology, existing T-DNA insertion mutant collections, and heterologous expression constructs, respectively. Here, we provide a detailed description of the methods for these inexpensive assays that can be reliably used to assess pollen-stigma interactions and used to identify new players regulating these processes.
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Affiliation(s)
- Hyun Kyung Lee
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Stuart Macgregor
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Daphne R Goring
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON, Canada.
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11
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Doucet J, Lee HK, Udugama N, Xu J, Qi B, Goring DR. Investigations into a putative role for the novel BRASSIKIN pseudokinases in compatible pollen-stigma interactions in Arabidopsis thaliana. BMC PLANT BIOLOGY 2019; 19:549. [PMID: 31829135 PMCID: PMC6907349 DOI: 10.1186/s12870-019-2160-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 11/25/2019] [Indexed: 05/04/2023]
Abstract
BACKGROUND In the Brassicaceae, the early stages of compatible pollen-stigma interactions are tightly controlled with early checkpoints regulating pollen adhesion, hydration and germination, and pollen tube entry into the stigmatic surface. However, the early signalling events in the stigma which trigger these compatible interactions remain unknown. RESULTS A set of stigma-expressed pseudokinase genes, termed BRASSIKINs (BKNs), were identified and found to be present in only core Brassicaceae genomes. In Arabidopsis thaliana Col-0, BKN1 displayed stigma-specific expression while the BKN2 gene was expressed in other tissues as well. CRISPR deletion mutations were generated for the two tandemly linked BKNs, and very mild hydration defects were observed for wild-type Col-0 pollen when placed on the bkn1/2 mutant stigmas. In further analyses, the predominant transcript for the stigma-specific BKN1 was found to have a premature stop codon in the Col-0 ecotype, but a survey of the 1001 Arabidopsis genomes uncovered three ecotypes that encoded a full-length BKN1 protein. Furthermore, phylogenetic analyses identified intact BKN1 orthologues in the closely related outcrossing Arabidopsis species, A. lyrata and A. halleri. Finally, the BKN pseudokinases were found to be plasma-membrane localized through the dual lipid modification of myristoylation and palmitoylation, and this localization would be consistent with a role in signaling complexes. CONCLUSION In this study, we have characterized the novel Brassicaceae-specific family of BKN pseudokinase genes, and examined the function of BKN1 and BKN2 in the context of pollen-stigma interactions in A. thaliana Col-0. Additionally, premature stop codons were identified in the predicted stigma specific BKN1 gene in a number of the 1001 A. thaliana ecotype genomes, and this was in contrast to the out-crossing Arabidopsis species which carried intact copies of BKN1. Thus, understanding the function of BKN1 in other Brassicaceae species will be a key direction for future studies.
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Affiliation(s)
- Jennifer Doucet
- Department of Cell & Systems Biology, University of Toronto, Toronto, M5S 3B2 Canada
| | - Hyun Kyung Lee
- Department of Cell & Systems Biology, University of Toronto, Toronto, M5S 3B2 Canada
| | - Nethangi Udugama
- Department of Cell & Systems Biology, University of Toronto, Toronto, M5S 3B2 Canada
| | - Jianfeng Xu
- School of Pharmacy & Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF UK
- College of Horticulture, Agricultural University of Hebei, Baoding City, 071001 Hebei Province China
| | - Baoxiu Qi
- School of Pharmacy & Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF UK
| | - Daphne R. Goring
- Department of Cell & Systems Biology, University of Toronto, Toronto, M5S 3B2 Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, M5S 3B2 Canada
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12
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Doucet J, Truong C, Frank-Webb E, Lee HK, Daneva A, Gao Z, Nowack MK, Goring DR. Identification of a role for an E6-like 1 gene in early pollen-stigma interactions in Arabidopsis thaliana. PLANT REPRODUCTION 2019; 32:307-322. [PMID: 31069543 DOI: 10.1007/s00497-019-00372-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 04/29/2019] [Indexed: 05/22/2023]
Abstract
We describe a function for a novel Arabidopsis gene, E6-like 1 (E6L1), that was identified as a highly expressed gene in the stigma and plays a role in early post-pollination stages. In Arabidopsis, successful pollen-stigma interactions are dependent on rapid recognition of compatible pollen by the stigmatic papillae located on the surface of the pistil and the subsequent regulation of pollen hydration and germination, and followed by the growth of pollen tubes through the stigma surface. Here we have described the function of a novel gene, E6-like 1 (E6L1), that was identified through the analysis of transcriptome datasets, as one of highest expressed genes in the stigma, and furthermore, its expression was largely restricted to the stigma and trichomes. The first E6 gene was initially identified as a highly expressed gene during cotton fiber development, and related E6-like predicted proteins are found throughout the Angiosperms. To date, no orthologous genes have been assigned a biological function. Both the Arabidopsis E6L1 and cotton E6 proteins are predicted to be secreted, and this was confirmed using an E6L1:RFP fusion construct. To further investigate E6L1's function, one T-DNA and two independent CRISPR-generated mutants were analyzed for compatible pollen-stigma interactions, and pollen hydration, pollen adhesion, and seed set were mildly impaired for the e6l1 mutants. This work identifies E6L1 as a novel stigmatic factor that plays a role during the early post-pollination stages in Arabidopsis.
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Affiliation(s)
- Jennifer Doucet
- Department of Cell and Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada
| | - Christina Truong
- Department of Cell and Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada
| | - Elizabeth Frank-Webb
- Department of Cell and Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada
| | - Hyun Kyung Lee
- Department of Cell and Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada
| | - Anna Daneva
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center of Plant Systems Biology, Ghent, Belgium
| | - Zhen Gao
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center of Plant Systems Biology, Ghent, Belgium
| | - Moritz K Nowack
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center of Plant Systems Biology, Ghent, Belgium
| | - Daphne R Goring
- Department of Cell and Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada.
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, M5S 3B2, Canada.
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13
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Shi S, Gao Q, Zuo T, Lei Z, Pu Q, Wang Y, Liu G, He X, Ren X, Zhu L. Identification and characterization of BoPUB3: a novel interaction protein with S-locus receptor kinase in Brassica oleracea L. Acta Biochim Biophys Sin (Shanghai) 2019; 51:723-733. [PMID: 31168565 DOI: 10.1093/abbs/gmz057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 04/03/2019] [Indexed: 12/27/2022] Open
Abstract
Armadillo repeat containing 1 (ARC1) is phosphorylated by S-locus receptor kinase (SRK) and functions as a positive regulator in self-incompatibility response of Brassica. However, ARC1 only causes partial breakdown of the self-incompatibility response, and other SRK downstream factors may also participate in the self-incompatibility signaling pathway. In the present study, to search for SRK downstream targets, a plant U-box protein 3 (BoPUB3) was identified from the stigma of Brassica oleracea L. BoPUB3 was highly expressed in the stigma, and its expression was increased with the stigma development and reached to the highest level in the mature-stage stigma. BoPUB3, a 76.8-kDa protein with 697 amino acids, is a member of the PUB-ARM family and contains three domain characteristics of BoARC1, including a U-box N-terminal domain, a U-box motif, and a C-terminal arm repeat domain. The phylogenic tree showed that BoPUB3 was close to BoARC1. The synteny analysis revealed that B. oleracea chromosomal region containing BoPUB3 had high synteny with the Arabidopsis thaliana chromosomal region containing AtPUB3 (At3G54790). In addition, the subcellular localization analysis showed that BoPUB3 primarily localized in the plasma membrane and also in the cytoplasm. The combination of the yeast two-hybrid and in vitro binding assay showed that both BoPUB3 and BoARC1 could interact with SRK kinase domain, and SRK showed much higher level of β-galactosidase activity in its interaction with BoPUB3 than with BoARC1. These results implied that BoPUB3 is a novel interactor with SRK, which lays a basis for further research on whether PUB3 participates in the self-incompatibility signaling pathway.
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Affiliation(s)
- Songmei Shi
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
- Centre of Excellence for Soil Biology, College of Resources and Environment, Southwest University, Chongqing, China
| | - Qiguo Gao
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
| | - Tonghong Zuo
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China
| | - Zhenze Lei
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
| | - Quanming Pu
- Nanchong Academy of Agricultural Sciences, Nanchong, China
| | - Yukui Wang
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China
| | - Guixi Liu
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
| | - Xinhua He
- Centre of Excellence for Soil Biology, College of Resources and Environment, Southwest University, Chongqing, China
- School of Biological Sciences, University of Western Australia, Perth, Western Australia, Australia
| | - Xuesong Ren
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China
| | - Liquan Zhu
- College of Agronomy and Biotechnology, Southwest University, Chongqing, China
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14
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Takeda S, Ochiai K, Kagaya Y, Egusa W, Morimoto H, Sakazono S, Osaka M, Nabemoto M, Suzuki G, Watanabe M, Suwabe K. Abscisic acid-mediated developmental flexibility of stigmatic papillae in response to ambient humidity in Arabidopsis thaliana. Genes Genet Syst 2018; 93:209-220. [PMID: 30473573 DOI: 10.1266/ggs.18-00025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Stigmatic papillae develop at the apex of the gynoecium and play an important role as a site of pollination. The papillae in Brassicaceae are of the dry and unicellular type, and more than 15,000 genes are expressed in the papillae; however, the molecular and physiological mechanisms of their development remain unknown. We found that the papillae in Arabidopsis thaliana change their length in response to altered ambient humidity: papillae of flowers incubated under high humidity elongated more than those under normal humidity conditions. Genetic analysis and transcriptome data suggest that an abscisic acid-mediated abiotic stress response mechanism regulates papilla length. Our data suggest a flexible regulation of papilla elongation at the post-anthesis stage, in response to abiotic stress, as an adaptation to environmental conditions.
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Affiliation(s)
- Seiji Takeda
- Laboratory of Cell and Genome Biology, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University.,Laboratory of Cell and Genome Biology, Biotechnology Research Department, Kyoto Prefectural Agriculture Forestry and Fisheries Technology Center
| | - Kohki Ochiai
- Laboratory of Cell and Genome Biology, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University
| | - Yasuaki Kagaya
- Laboratory of Plant Functional Genomics, Life Science Research Center, Mie University.,Laboratory of Plant Functional Genomics, Graduate School of Regional Innovation Studies, Mie University
| | - Wataru Egusa
- Laboratory of Molecular Genetics and Breeding, Graduate School of Bioresources, Mie University
| | - Hiroaki Morimoto
- Laboratory of Molecular Genetics and Breeding, Graduate School of Bioresources, Mie University
| | - Satomi Sakazono
- Laboratory of Plant Molecular Breeding, Graduate School of Life Sciences, Tohoku University
| | - Masaaki Osaka
- Laboratory of Plant Molecular Breeding, Graduate School of Life Sciences, Tohoku University
| | - Moe Nabemoto
- Laboratory of Plant Molecular Breeding, Graduate School of Life Sciences, Tohoku University
| | - Go Suzuki
- Laboratory of Plant Molecular Genetics, Division of Natural Science, Osaka Kyoiku University
| | - Masao Watanabe
- Laboratory of Plant Molecular Breeding, Graduate School of Life Sciences, Tohoku University
| | - Keita Suwabe
- Laboratory of Molecular Genetics and Breeding, Graduate School of Bioresources, Mie University
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15
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Jany E, Nelles H, Goring DR. The Molecular and Cellular Regulation of Brassicaceae Self-Incompatibility and Self-Pollen Rejection. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 343:1-35. [PMID: 30712670 DOI: 10.1016/bs.ircmb.2018.05.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In flowering plants, sexual reproduction is actively regulated by cell-cell communication between the male pollen and female pistil, and many species possess self-incompatibility systems for the selective rejection of self-pollen to maintain genetic diversity. The Brassicaceae self-incompatibility pathway acts early on when pollen grains have landed on the stigmatic papillae at the top of the pistil. Extensive studies have revealed that self-pollen rejection in the Brassicaceae is initiated by an S-haplotype-specific interaction between two polymorphic proteins: the pollen S-locus protein 11/S cysteine-rich (SP11/SCR) ligand and the stigma S receptor kinase (SRK). While the different S-haplotypes are typically codominant, there are several examples of dominant-recessive interactions, and a small RNA-based regulation of SP11/SCR expression has been uncovered as a mechanism behind these genetic interactions. Recent research has also added to our understanding of various cellular components in the pathway leading from the SP11/SCR-SRK interaction, including two signaling proteins, the M-locus protein kinase (MLPK) and the ARM-repeat containing 1 (ARC1) E3 ligase, as well as calcium fluxes and induction of autophagy in the stigmatic papillae. Finally, a better understanding of the compatible pollen responses that are targeted by the self-incompatibility pathway is starting to emerge, and this will allow us to more fully understand how the Brassicaceae self-incompatibility pathway causes self-pollen rejection. Here, we provide an overview of the field, highlighting recent contributions to our understanding of Brassicaceae self-incompatibility, and draw comparisons to a recently discovered unilateral incompatibility system.
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Affiliation(s)
- Eli Jany
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Hayley Nelles
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Daphne R Goring
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada; Centre for Genome Analysis & Function, University of Toronto, Toronto, ON, Canada
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16
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Following the Time-Course of Post-pollination Events by Transmission Electron Microscopy (TEM): Buildup of Exosome-Like Structures with Compatible Pollinations. Methods Mol Biol 2018. [PMID: 27665553 DOI: 10.1007/978-1-4939-3804-9_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
In the Brassicaceae, the dry stigma is an initial barrier to pollen acceptance as the stigmatic papillae lack surface secretions, and consequently rapid cellular responses are required to accept compatible pollen. Regulated secretion with secretory vesicles or multivesicular bodies is initiated in the stigmatic papillae towards the compatible pollen grain. In self-incompatible species, this basal compatible pollen response is superseded by the self-incompatibility signaling pathway where the secretory organelles are found in autophagosomes and vacuole for destruction. In this chapter, we describe a detailed protocol using the Transmission Electron Microscope to document the rapid cellular changes that occur in the stigmatic papillae in response to compatible versus self-incompatible pollen, at the pollen-stigma interface.
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17
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Goring DR. Exocyst, exosomes, and autophagy in the regulation of Brassicaceae pollen-stigma interactions. JOURNAL OF EXPERIMENTAL BOTANY 2017; 69:69-78. [PMID: 29036428 DOI: 10.1093/jxb/erx340] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Brassicaceae pollen-stigma interactions have been extensively studied in Brassica and Arabidopsis species to identify cellular events triggered in the stigmatic papillae by pollen contact. Compatible pollinations are linked to the activation of basal cellular responses in the stigmatic papillae, which include calcium gradients, actin networks, and polarized secretion. The occurrence of these cellular events in stigmatic papillae coincides with the stages of pollen hydration and pollen tube entry into the stigmatic papillar cell wall. However, the form of the vesicle trafficking appears to differ between species, with vesicle-like structures detected in Arabidopsis species while exosomes were found to be secreted in Brassica species. Around the same timeframe, self-incompatible pollen recognition leads altered cellular responses in the stigmatic papillae to interfere with basal compatible pollen responses and disrupt regulated secretion, causing self-pollen rejection. Here, the literature on the changing cellular dynamics in the stigmatic papillae following pollination is reviewed and discussed in the context of other well-characterized examples of polarized secretion in plants.
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Affiliation(s)
- Daphne R Goring
- Department of Cell & Systems Biology, University of Toronto, Canada M5S 3B2
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Canada M5S 3B2
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18
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Wang L, Clarke LA, Eason RJ, Parker CC, Qi B, Scott RJ, Doughty J. PCP-B class pollen coat proteins are key regulators of the hydration checkpoint in Arabidopsis thaliana pollen-stigma interactions. THE NEW PHYTOLOGIST 2017; 213:764-777. [PMID: 27596924 PMCID: PMC5215366 DOI: 10.1111/nph.14162] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/23/2016] [Indexed: 05/09/2023]
Abstract
The establishment of pollen-pistil compatibility is strictly regulated by factors derived from both male and female reproductive structures. Highly diverse small cysteine-rich proteins (CRPs) have been found to play multiple roles in plant reproduction, including the earliest stages of the pollen-stigma interaction. Secreted CRPs found in the pollen coat of members of the Brassicaceae, the pollen coat proteins (PCPs), are emerging as important signalling molecules that regulate the pollen-stigma interaction. Using a combination of protein characterization, expression and phylogenetic analyses we identified a novel class of Arabidopsis thaliana pollen-borne CRPs, the PCP-Bs (for pollen coat protein B-class) that are related to embryo surrounding factor (ESF1) developmental regulators. Single and multiple PCP-B mutant lines were utilized in bioassays to assess effects on pollen hydration, adhesion and pollen tube growth. Our results revealed that pollen hydration is severely impaired when multiple PCP-Bs are lost from the pollen coat. The hydration defect also resulted in reduced pollen adhesion and delayed pollen tube growth in all mutants studied. These results demonstrate that AtPCP-Bs are key regulators of the hydration 'checkpoint' in establishment of pollen-stigma compatibility. In addition, we propose that interspecies diversity of PCP-Bs may contribute to reproductive barriers in the Brassicaceae.
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Affiliation(s)
- Ludi Wang
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Lisa A. Clarke
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Russell J. Eason
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | | | - Baoxiu Qi
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Rod J. Scott
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - James Doughty
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
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19
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Doucet J, Lee HK, Goring DR. Pollen Acceptance or Rejection: A Tale of Two Pathways. TRENDS IN PLANT SCIENCE 2016; 21:1058-1067. [PMID: 27773670 DOI: 10.1016/j.tplants.2016.09.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 09/02/2016] [Accepted: 09/26/2016] [Indexed: 05/21/2023]
Abstract
While the molecular and cellular basis of self-incompatibility leading to self-pollen rejection in the Brassicaceae has been extensively studied, relatively little attention has been paid to compatible pollen recognition and the corresponding cellular responses in the stigmatic papillae. This is now changing because research has started to uncover steps in the Brassicaceae 'basal compatible pollen response pathway' in the stigma leading to pollen hydration and germination. Furthermore, recent studies suggest that self-incompatible pollen activates both the basal compatible pathway and the self-incompatibility pathway in the stigma, with the self-incompatibility response ultimately prevailing to reject self-pollen. We review here recent discoveries in both pathways and discuss how compatible pollen is accepted by the stigma versus the rejection of self-incompatible pollen.
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Affiliation(s)
- Jennifer Doucet
- Department of Cell and Systems Biology, University of Toronto, Toronto M5S 3B2, Canada
| | - Hyun Kyung Lee
- Department of Cell and Systems Biology, University of Toronto, Toronto M5S 3B2, Canada
| | - Daphne R Goring
- Department of Cell and Systems Biology, University of Toronto, Toronto M5S 3B2, Canada; Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto M5S 3B2, Canada.
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20
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Shi S, Gao Q, Zeng J, Liu X, Pu Q, Liu G, Zhang H, Yang X, Zhu L. N-terminal domains of ARC1 are essential for interaction with the N-terminal region of Exo70A1 in transducing self-incompatibility of Brassica oleracea. Acta Biochim Biophys Sin (Shanghai) 2016; 48:777-87. [PMID: 27590064 DOI: 10.1093/abbs/gmw075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 04/11/2016] [Indexed: 12/28/2022] Open
Abstract
Self-incompatibility (SI) is an important mating system to prevent inbreeding and promote outcrossing. ARC1 and Exo70A1 function as the downstream targets of the S-locus receptor kinase and play conservative roles in Brassica SI signaling. Based on the sequence homology, Exo70A1 is divided into four subdomains: leucine zipper (Leu(128)-Leu(149)), hypervariable region (Ser(172)-Leu(197)), SUMO modification motif (Glu(260)-Ile(275)), and pfamExo70 domain (His(271)-Phe(627)). ARC1 contains four domains as follows: leucine zipper (Leu(116)-Leu(137)), coiled-coil domain (Thr(210)-Val(236)), U-box (Asp(282)-Trp(347)) motif, and ARM (Ala(415)-Thr(611)) domain. Bioinformatics analysis, yeast two-hybrid screening and pull-down assays show that leucine zipper and coiled-coil motifs of ARC1116-236 are required for the interaction with Exo70A1, while the addition of ARM motif results in loss of the interaction with Exo70A1. Meanwhile, the N-terminal of Exo70A1 without any domains shows a weak interaction with ARC1, and the level of LacZ expression increases with addition of leucine zipper and reaches the maximum value with hypervariable region and SUMO modification motif, indicating that hypervariable region and SUMO modification motif of Exo70A1172-275 is mainly responsible for the binding with ARC1, whereas pfamExo70 domain has little affinity for ARC1. Lys(181) located in the Exo70A1 hypervariable region may be the ubiquitination site mediating the interaction between ARC1 and Exo70A1. Therefore, both the leucine zipper with coiled-coil structure of ARC1116-236, and the hypervariable region and SUMO modification motif of Exo70A1172-275 are the core interaction domains between ARC1 and Exo70A1. Any factors affecting these core domains would be the regulators of ARC1 mediating ubiquitin degradation in self-incompatible system.
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Affiliation(s)
- Songmei Shi
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China Laboratory of Plant Biochemistry and Molecular Biology, College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China
| | - Qiguo Gao
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China
| | - Jing Zeng
- Laboratory of Plant Biochemistry and Molecular Biology, College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China
| | - Xiaohuan Liu
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China
| | - Quanming Pu
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China
| | - Guixi Liu
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China
| | - Hecui Zhang
- Laboratory of Plant Biochemistry and Molecular Biology, College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China
| | - Xiaohong Yang
- Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education/College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400715, China
| | - Liquan Zhu
- Laboratory of Plant Biochemistry and Molecular Biology, College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China
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21
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Vukašinović N, Žárský V. Tethering Complexes in the Arabidopsis Endomembrane System. Front Cell Dev Biol 2016; 4:46. [PMID: 27243010 PMCID: PMC4871884 DOI: 10.3389/fcell.2016.00046] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/02/2016] [Indexed: 12/30/2022] Open
Abstract
Targeting of endomembrane transport containers is of the utmost importance for proper land plant growth and development. Given the immobility of plant cells, localized membrane vesicle secretion and recycling are amongst the main processes guiding proper cell, tissue and whole plant morphogenesis. Cell wall biogenesis and modification are dependent on vectorial membrane traffic, not only during normal development, but also in stress responses and in plant defense against pathogens and/or symbiosis. It is surprising how little we know about these processes in plants, from small GTPase regulation to the tethering complexes that act as their effectors. Tethering factors are single proteins or protein complexes mediating first contact between the target membrane and arriving membrane vesicles. In this review we focus on the tethering complexes of the best-studied plant model—Arabidopsis thaliana. Genome-based predictions indicate the presence of all major tethering complexes in plants that are known from a hypothetical last eukaryotic common ancestor (LECA). The evolutionary multiplication of paralogs of plant tethering complex subunits has produced the massively expanded EXO70 family, indicating a subfunctionalization of the terminal exocytosis machinery in land plants. Interpretation of loss of function (LOF) mutant phenotypes has to consider that related, yet clearly functionally-specific complexes often share some common core subunits. It is therefore impossible to conclude with clarity which version of the complex is responsible for the phenotypic deviations observed. Experimental interest in the analysis of plant tethering complexes is growing and we hope to contribute with this review by attracting even more attention to this fascinating field of plant cell biology.
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Affiliation(s)
- Nemanja Vukašinović
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University Prague, Czech Republic
| | - Viktor Žárský
- Laboratory of Cell Morphogenesis, Department of Experimental Plant Biology, Faculty of Science, Charles University Prague, Czech Republic
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22
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Wipf HML, Meindl GA, Ashman TL. A first test of elemental allelopathy via heterospecific pollen receipt. AMERICAN JOURNAL OF BOTANY 2016; 103:514-521. [PMID: 26451033 DOI: 10.3732/ajb.1500187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 06/11/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Coflowering plants often share pollinators and may receive mixed species pollen loads. Although detrimental effects of heterospecific pollen receipt have been documented, trait-based modifiers of interactions on the stigma remain largely unknown. Chemicals that mediate interactions between sporophytes could also influence pollen-pollen or pollen-style interactions. We test for the first time whether nickel (Ni) accumulation in pollen can lead to "elemental allelopathy" and intensify the fitness consequences of heterospecific pollen receipt. METHODS We grew Ni-hyperaccumulator Streptanthus polygaloides in soils augmented with three concentrations of Ni, measured pollen Ni concentration, and hand-pollinated non-Ni hyperaccumulator Mimulus guttatus. We assayed pollen germination, tube growth and seeds of M. guttatus after pure and mixed species pollinations. KEY RESULTS Streptanthus polygaloides pollen accumulated Ni in proportion to soil availability and at levels significantly greater than M. guttatus pollen. Although receipt of S. polygaloides pollen increased M. guttatus pollen germination, it decreased the proportion of pollen tubes reaching the ovary and seed number. Increased Ni in pollen, however, did not significantly intensify the effect of S. polygaloides pollen receipt on M. guttatus seed production. CONCLUSIONS Different levels of Ni in the pollen of S. polygaloides achieved in the greenhouse did not significantly reduce the fitness of M. guttatus. Stigma tolerance to Ni may also have contributed to the lack of response to increased Ni in heterospecific pollen. This study paves the way for additional tests in other metal hyperaccumulators and recipients, and to identify mechanisms of interactions on the stigma.
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Affiliation(s)
- Heidi M-L Wipf
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA
| | - George A Meindl
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA
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23
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Robinson DG, Ding Y, Jiang L. Unconventional protein secretion in plants: a critical assessment. PROTOPLASMA 2016; 253:31-43. [PMID: 26410830 DOI: 10.1007/s00709-015-0887-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 09/18/2015] [Indexed: 05/27/2023]
Abstract
Unconventional protein secretion (UPS) is a collective term for mechanisms by which cytosolic proteins that lack a signal peptide ("leaderless secretory proteins" (LSPs)) can gain access to the cell exterior. Numerous examples of UPS have been well documented in animal and yeast cells. In contrast, our understanding of the mechanism(s) and function of UPS in plants is very limited. This review evaluates the available literature on this subject. The apparent large numbers of LSPs in the plant secretome suggest that UPS also occurs in plants but is not a proof. Although the direct transport of LSPs across the plant plasma membrane (PM) has not yet been described, it is possible that as in other eukaryotes, exosomes may be released from plant cells through fusion of multivesicular bodies (MVBs) with the PM. In this way, LSPs, but also small RNAs (sRNAs), that are passively taken up from the cytosol into the intraluminal vesicles of MVBs, could reach the apoplast. Another possible mechanism is the recently discovered exocyst-positive organelle (EXPO), a double-membrane-bound compartment, distinct from autophagosomes, which appears to sequester LSPs.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, D-69120, Heidelberg, Germany.
| | - Yu Ding
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Liu J, Zhang H, Lian X, Converse R, Zhu L. Identification of Interacting Motifs Between Armadillo Repeat Containing 1 (ARC1) and Exocyst 70 A1 (Exo70A1) Proteins in Brassica oleracea. Protein J 2015; 35:34-43. [DOI: 10.1007/s10930-015-9644-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Disruption of OsEXO70A1 Causes Irregular Vascular Bundles and Perturbs Mineral Nutrient Assimilation in Rice. Sci Rep 2015; 5:18609. [PMID: 26691393 PMCID: PMC4686888 DOI: 10.1038/srep18609] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 11/23/2015] [Indexed: 11/08/2022] Open
Abstract
Normal uptake, transportation, and assimilation of primary nutrients are essential to plant growth. Tracheary elements (TEs) are tissues responsible for the transport of water and minerals and characterized by patterned secondary cell wall (SCW) thickening. Exocysts are involved in the regulation of SCW deposition by mediating the targeted transport of materials and enzymes to specific membrane areas. EXO70s are highly duplicated in plants and provide exocysts with functional specificity. In this study, we report the isolation of a rice mutant rapid leaf senescence2 (rls2) that exhibits dwarfism, ferruginous spotted necrotic leaves, decreased hydraulic transport, and disordered primary nutrient assimilation. Histological analysis of rls2-1 mutants has indicated impaired cell expansion, collapsed vascular tissues, and irregular SCW deposition. Map-based cloning has revealed that RLS2 encodes OsEXO70A1, which is one of the 47 members of EXO70s in rice. RLS2 was widely expressed and spatially restricted in vascular bundles. Subcellular localization analysis demonstrated that RLS2 was present on both membrane and nuclear regions. Expression analysis revealed that mutations in rls2 triggers transcriptional fluctuation of orthologous EXO70 genes and affects genes involved in primary nutrient absorption and transport. In brief, our study revealed that RLS2 is required for normal vascular bundle differentiation and primary nutrient assimilation.
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Chi Y, Yang Y, Li G, Wang F, Fan B, Chen Z. Identification and characterization of a novel group of legume-specific, Golgi apparatus-localized WRKY and Exo70 proteins from soybean. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:3055-70. [PMID: 25805717 PMCID: PMC4449531 DOI: 10.1093/jxb/erv104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Many plant genes belong to families that arise from extensive proliferation and diversification allowing the evolution of functionally new proteins. Here we report the characterization of a group of proteins evolved from WRKY and exocyst complex subunit Exo70 proteins through fusion with a novel transmembrane (TM) domain in soybean (Glycine max). From the soybean genome, we identified a novel WRKY-related protein (GmWRP1) that contains a WRKY domain with no binding activity for W-box sequences. GFP fusion revealed that GmWRP1 was targeted to the Golgi apparatus through its N-terminal TM domain. Similar Golgi-targeting TM domains were also identified in members of a new subfamily of Exo70J proteins involved in vesicle trafficking. The novel TM domains are structurally most similar to the endosomal cytochrome b561 from birds and close homologues of GmWRP1 and GmEx070J proteins with the novel TM domain have only been identified in legumes. Transient expression of some GmExo70J proteins or the Golgi-targeting TM domain in tobacco altered the subcellular structures labelled by a fluorescent Golgi marker. GmWRP1 transcripts were detected at high levels in roots, flowers, pods, and seeds, and the expression levels of GmWRP1 and GmExo70J genes were elevated with increased age in leaves. The legume-specific, Golgi apparatus-localized GmWRP1 and GmExo70J proteins are probably involved in Golgi-mediated vesicle trafficking of biological molecules that are uniquely important to legumes.
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Affiliation(s)
- Yingjun Chi
- Department of Horticulture, Zijingang Campus, 866 Yuhangtang Road, Zhejiang University, Hangzhou, 310058, China
| | - Yan Yang
- Department of Horticulture, Zijingang Campus, 866 Yuhangtang Road, Zhejiang University, Hangzhou, 310058, China
| | - Guiping Li
- Department of Horticulture, Zijingang Campus, 866 Yuhangtang Road, Zhejiang University, Hangzhou, 310058, China
| | - Fei Wang
- Department of Botany and Plant Pathology, 915W. State Street, Purdue University, West Lafayette, IN 47907, USA
| | - Baofang Fan
- Department of Botany and Plant Pathology, 915W. State Street, Purdue University, West Lafayette, IN 47907, USA
| | - Zhixiang Chen
- Department of Horticulture, Zijingang Campus, 866 Yuhangtang Road, Zhejiang University, Hangzhou, 310058, China Department of Botany and Plant Pathology, 915W. State Street, Purdue University, West Lafayette, IN 47907, USA
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Yamamoto M, Nishio T. Commonalities and differences between Brassica and Arabidopsis self-incompatibility. HORTICULTURE RESEARCH 2014; 1:14054. [PMID: 26504553 PMCID: PMC4596330 DOI: 10.1038/hortres.2014.54] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 09/12/2014] [Accepted: 09/12/2014] [Indexed: 05/12/2023]
Abstract
In higher plants, the self-incompatibility mechanism is important for inhibition of self-fertilization and facilitation of out-crossing. In Brassicaceae, the self-incompatibility response is mediated by allele-specific interaction of the stigma-localized S-locus receptor kinase (SRK) with the pollen coat-localized ligand (SCR/SP11). All self-incompatible Brassicaceae plants analyzed have been found to have the SRK and SCR/SP11 genes in the S-locus region. Although Arabidopsis thaliana is self-compatible, transformation with functional SRK-SCR genes from self-incompatible Arabidopsis species confers the self-incompatibility phenotype to A. thaliana. The allele-specific interaction between SRK and SCR activates the downstream signaling cascade of self-incompatibility. Yeast two-hybrid analysis with a kinase domain of SRK as bait and genetic analysis suggested several candidate components of self-incompatibility signaling in Brassica. Recently, A. thaliana genes orthologous to the identified genes for Brassica self-incompatibility signaling were evaluated by using a self-incompatible transgenic A. thaliana plant and these orthologous genes were found not to be involved in self-incompatibility signaling in the transgenic A. thaliana. In this review, we describe common and different aspects of S-locus genomic regions and self-incompatibility signaling between Brassica and Arabidopsis.
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Affiliation(s)
- Masaya Yamamoto
- Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan
| | - Takeshi Nishio
- Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan
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