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Li Y, Zhang W, Yang Y, Liang X, Lu S, Ma C, Dai C. BnaPLDα1-BnaMPK6 Involved in NaCl-Mediated Overcoming of Self-Incompatibility in Brassica napus L. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2024; 345:112116. [PMID: 38750797 DOI: 10.1016/j.plantsci.2024.112116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 06/11/2024]
Abstract
Self-incompatibility (SI) is an important genetic mechanism exploited by numerous angiosperm species to prevent inbreeding. This mechanism has been widely used in the breeding of SI trilinear hybrids of Brassica napus. The SI responses in these hybrids can be overcome by using a salt (NaCl) solution, which is used for seed propagation in SI lines. However, the mechanism underlying the NaCl-induced breakdown of the SI response in B. napus remains unclear. Here, we investigated the role of two key proteins, BnaPLDα1 and BnaMPK6, in the breakdown of SI induced by NaCl. Pollen grain germination and seed set were reduced in BnaPLDα1 triple mutants following incompatible pollination with NaCl treatment. Conversely, SI responses were partially abolished by overexpression of BnaC05.PLDα1 without salt treatment. Furthermore, we observed that phosphatidic acid (PA) produced by BnaPLDα1 bound to B. napus BnaMPK6. The suppression and enhancement of the NaCl-induced breakdown of the SI response in B. napus were observed in BnaMPK6 quadruple mutants and BnaA05.MPK6 overexpression lines, respectively. Moreover, salt-induced stigmatic reactive oxygen species (ROS) accumulation had a minimal effect on the NaCl-induced breakdown of the SI response. In conclusion, our results demonstrate the essential role of the BnaPLDα1-PA-BnaMPK6 pathway in overcoming the SI response to salt treatment in SI B. napus. Additionally, our study provides new insights into the relationship between SI signaling and salt stress response. SIGNIFICANCE STATEMENT: A new molecular mechanism underlying the breakdown of the NaCl-induced self-incompatibility (SI) response in B. napus has been discovered. It involves the induction of BnaPLDα1 expression by NaCl, followed by the activation of BnaMPK6 through the production of phosphatidic acid (PA) by BnaPLDα1. Ultimately, this pathway leads to the breakdown of SI. The involvement of the BnaPLDα1-PA-BnaMPK6 pathway in overcoming the SI response following NaCl treatment provides new insights into the relationship between SI signalling and the response to salt stress.
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Affiliation(s)
- Yuanyuan Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - WenXuan Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Yong Yang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiaomei Liang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Shaoping Lu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Chaozhi Ma
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan 430070, China
| | - Cheng Dai
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
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Nasrallah JB. Stop and go signals at the stigma-pollen interface of the Brassicaceae. PLANT PHYSIOLOGY 2023; 193:927-948. [PMID: 37423711 PMCID: PMC10517188 DOI: 10.1093/plphys/kiad301] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 05/16/2023] [Indexed: 07/11/2023]
Affiliation(s)
- June B Nasrallah
- Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
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Nasrallah JB. Self-incompatibility in the Brassicaceae: Regulation and mechanism of self-recognition. Curr Top Dev Biol 2019; 131:435-452. [DOI: 10.1016/bs.ctdb.2018.10.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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Activation of Self-Incompatibility Signaling in Transgenic Arabidopsis thaliana Is Independent of AP2-Based Clathrin-Mediated Endocytosis. G3-GENES GENOMES GENETICS 2018; 8:2231-2239. [PMID: 29720392 PMCID: PMC6027874 DOI: 10.1534/g3.118.200231] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Internalization of plasma membrane (PM)-localized ligand-activated receptor kinases and their trafficking to sorting endosomes have traditionally been viewed as functioning primarily in the down-regulation of receptor signaling, but are now considered to be also essential for signaling by some receptors. A major mechanism for internalization of PM proteins is clathrin-mediated endocytosis (CME). CME is mediated by the Adaptor Protein Complex 2 (AP2), which is involved in interaction of the AP2 μ-adaptin subunit with a tyrosine-based Yxxϕ motif located in the cytoplasmic domain of the cargo protein. In this study, we investigated the role of AP2-mediated CME for signaling by the S-locus receptor kinase (SRK), a protein localized in the PM of stigma epidermal cells, which, together with its pollen coat-localized S-locus cysteine-rich (SCR) ligand, functions in the self-incompatibility (SI) response of the Brassicaceae. Using Arabidopsis thaliana plants that were made self-incompatible by transformation with an A. lyrata-derived SRK/SCR gene pair, we tested the effect on SI of site-directed mutations in each of the two Yxxϕ motifs in SRK and of a CRISPR/Cas9-induced null mutation in the AP2 μ-adaptin gene AP2M. Both in vitro SRK kinase activity and the in planta SI response were abolished by substitution of tyrosine in one of the two Yxxϕ motifs, but were unaffected by elimination of either the second Yxxϕ motif or AP2M function. Thus, AP2-mediated CME is considered to be unnecessary for SRK signaling in the SI response.
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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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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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Tantikanjana T, Nasrallah JB. Ligand-Mediated cis-Inhibition of Receptor Signaling in the Self-Incompatibility Response of the Brassicaceae. PLANT PHYSIOLOGY 2015; 169:1141-54. [PMID: 26269543 PMCID: PMC4587449 DOI: 10.1104/pp.15.00572] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/11/2015] [Indexed: 05/02/2023]
Abstract
The inhibition of self-pollination in self-incompatible Brassicaceae is based on allele-specific trans-activation of the highly polymorphic S-locus receptor kinase (SRK), which is displayed at the surface of stigma epidermal cells, by its even more polymorphic pollen coat-localized ligand, the S-locus cysteine-rich (SCR) protein. In an attempt to achieve constitutive activation of SRK and thus facilitate analysis of self-incompatibility (SI) signaling, we coexpressed an Arabidopsis lyrata SCR variant with its cognate SRK receptor in the stigma epidermal cells of Arabidopsis (Arabidopsis thaliana) plants belonging to the C24 accession, in which expression of SRK and SCR had been shown to exhibit a robust SI response. Contrary to expectation, however, coexpression of SRK and SCR was found to inhibit SRK-mediated signaling and to disrupt the SI response. This phenomenon, called cis-inhibition, is well documented in metazoans but has not as yet been reported for plant receptor kinases. We demonstrate that cis-inhibition of SRK, like its trans-activation, is based on allele-specific interaction between receptor and ligand. We also show that stigma-expressed SCR causes entrapment of its SRK receptor in the endoplasmic reticulum, thus disrupting the proper targeting of SRK to the plasma membrane, where the receptor would be available for productive interaction with its pollen coat-derived SCR ligand. Although based on an artificial cis-inhibition system, the results suggest novel strategies of pollination control for the generation of hybrid cultivars and large-scale seed production from hybrid plants in Brassicaceae seed crops and, more generally, for inhibiting cell surface receptor function and manipulating signaling pathways in plants.
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Affiliation(s)
- Titima Tantikanjana
- Section of Plant Biology, School of Integrative Plant Sciences, Cornell University, Ithaca, New York 14953
| | - June B Nasrallah
- Section of Plant Biology, School of Integrative Plant Sciences, Cornell University, Ithaca, New York 14953
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Yamamoto M, Tantikanjana T, Nishio T, Nasrallah ME, Nasrallah JB. Site-specific N-glycosylation of the S-locus receptor kinase and its role in the self-incompatibility response of the brassicaceae. THE PLANT CELL 2014; 26:4749-62. [PMID: 25480368 PMCID: PMC4311203 DOI: 10.1105/tpc.114.131987] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The S-locus receptor kinase SRK is a highly polymorphic transmembrane kinase of the stigma epidermis. Through allele-specific interaction with its pollen coat-localized ligand, the S-locus cysteine-rich protein SCR, SRK is responsible for recognition and inhibition of self pollen in the self-incompatibility response of the Brassicaceae. The SRK extracellular ligand binding domain contains several potential N-glycosylation sites that exhibit varying degrees of conservation among SRK variants. However, the glycosylation status and functional importance of these sites are currently unclear. We investigated this issue in transgenic Arabidopsis thaliana stigmas that express the Arabidopsis lyrata SRKb variant and exhibit an incompatible response toward SCRb-expressing pollen. Analysis of single- and multiple-glycosylation site mutations of SRKb demonstrated that, although five of six potential N-glycosylation sites in SRKb are glycosylated in stigmas, N-glycosylation is not important for SCRb-dependent activation of SRKb. Rather, N-glycosylation functions primarily to ensure the proper and efficient subcellular trafficking of SRK to the plasma membrane. The study provides insight into the function of a receptor that regulates a critical phase of the plant life cycle and represents a valuable addition to the limited information available on the contribution of N-glycosylation to the subcellular trafficking and function of plant receptor kinases.
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Affiliation(s)
- Masaya Yamamoto
- Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850
| | - Titima Tantikanjana
- Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850
| | - Takeshi Nishio
- Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-855, Japan
| | - Mikhail E Nasrallah
- Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850
| | - June B Nasrallah
- Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850
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