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1.
Gene ; 756: 144917, 2020 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-32590104

RESUMO

The self-incompatibility system of Corylus is a sporophytic type that is phenotypically similar to that of Brassica. While the molecular mechanism of sporophytic self-incompatibility (SSI) has been investigated extensively in Brassica (Brassicaceae), little is known about the corresponding mechanism in Corylus (Betulaceae). Here, we discuss the SSI mechanism with respect to S-locus receptor kinase (SRK) gene homologs. To obtain two SRK candidate unigenes, we compared all of the unigenes in a transcriptional protein database from our previous study with BnSRK-1 (AB270767) using BLASTX with a cutoff e-value of 10-5. We then cloned the full-length cDNA of ChaSRK1 and ChaSRK2 genes from Ping'ou hybrid hazelnut (Corylus heterophylla × Corylus avellana) using RACE techniques. Bioinformatics approaches were used to analyze the cDNA sequences, protein sequences, and domains of the encoded proteins. The full-length ChaSRK1 cDNA was 2883 base pairs (bp) with a coding sequence (CDS) of 2,547 bp encoding 849 amino acid residues. The full-length ChaSRK2 cDNA was 2,693 bp, with a CDS of 2,433 bp encoding 811 amino acids. The ChaSRK1/2 proteins contained an S-domain (extracellular domain), a transmembrane domain, a Ser/Thr protein kinase active site (kinase domain), and DUF3660 and/or DUF3403 domains. The lengths of 18 partial SRK homologs ranged from 1347 to 1451 bp, and they contained the same structural domains as ChaSRK1 and ChaSRK2. Phylogenetic analysis revealed that all SRK homologs could be divided into two categories that were similar to the classification of SRKs in Brassica. The expression patterns of ChaSRK1 and ChaSRK2 differed: ChaSRK2 was predominantly expressed in mature stigmatic styles, while ChaSRK1 was expressed in other tissues with the highest in the root tips of Corylus. Using dual-color fluorescence in situ hybridization, ChaSRK1/2 expression was found to be localized in papillar cells. Collectively, these results revealed that SRKs from Corylus had similar characteristics to SRKs from Brassica. We therefore speculated that the SSI mechanism in Corylus might be more similar to the Brassica mechanism than to other SSI types.


Assuntos
Corylus/enzimologia , Corylus/fisiologia , Proteínas de Plantas/genética , Proteínas Quinases/genética , Autoincompatibilidade em Angiospermas , Sequência de Bases , Brassica/fisiologia , Clonagem Molecular , Corylus/genética , Filogenia , Alinhamento de Sequência , Transcriptoma
2.
Nat Commun ; 11(1): 1404, 2020 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-32179752

RESUMO

Selfing is a frequent evolutionary trend in angiosperms, and is a suitable model for studying the recurrent patterns underlying adaptive evolution. Many plants avoid self-fertilization by physiological processes referred to as self-incompatibility (SI). In the Brassicaceae, direct and specific interactions between the male ligand SP11/SCR and the female receptor kinase SRK are required for the SI response. Although Arabidopsis thaliana acquired autogamy through loss of these genes, molecular evolution contributed to the spread of self-compatibility alleles requires further investigation. We show here that in this species, dominant SRK silencing genes have evolved at least twice. Different inverted repeat sequences were found in the relic SRK region of the Col-0 and C24 strains. Both types of inverted repeats suppress the functional SRK sequence in a dominant fashion with different target specificities. It is possible that these dominant suppressors of SI contributed to the rapid fixation of self-compatibility in A. thaliana.


Assuntos
Arabidopsis/fisiologia , Flores/genética , Autoincompatibilidade em Angiospermas , Alelos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Brassicaceae/genética , Brassicaceae/fisiologia , Evolução Molecular , Flores/metabolismo , Regulação da Expressão Gênica de Plantas
3.
Plant Mol Biol ; 103(1-2): 129-139, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32088832

RESUMO

KEY MESSAGE: The structurally simplest amino acid glycine could make contribution to nuclease activity of S-RNase and self-incompatibility in S-RNase-based plants. S-RNase is regarded as inhibitor of self-pollen tube in S-RNase-based self-incompatibility plants. Certain residues like histidine are necessary for RNase activity and self-incompatibility; however, it is unknown whether any other residues contribute to this. Previously, we identified an association between the self-compatible Chinese pear (Pyrus × bretschneideri) cultivar 'Yanzhuang' (YZ) and a mutation causing a residue shift (glycine-to-valine) in the 2nd conserved region (C2) of S21-RNase; however, it was unclear how this nonpolar aliphatic amino acid substitution caused self-compatibility. In this study, we observed that 'YZ' offspring were self-compatible when S21-RNases were all mutated. In vitro pollen tube (S21S21) growth was not completely arrested by the mutated S21-RNase. Residue frequency analysis showed that the glycine residue is highly conserved in diverse S-RNases across many plant species. We therefore generated a mutated petunia SV'-RNase (glycine to valine) and transformed it into S3LS3L petunia. The transformed pistil could not inhibit SV pollen tubes. Three-dimensional protein prediction suggested that the glycine-to-valine mutation alters the spatial structure near the active site, and RNase activity of mutated S-RNase was reducing. Thus, the glycine residue in the C2 is essential for RNase activity, substitution of this residue leads to a failure of self-incompatibility.


Assuntos
Pyrus/genética , Ribonucleases/genética , Autoincompatibilidade em Angiospermas , Domínio Catalítico , Sequência Conservada , Glicina/metabolismo , Mutação , Melhoramento Vegetal , Tubo Polínico , Pyrus/fisiologia , Ribonucleases/metabolismo , Autoincompatibilidade em Angiospermas/genética
4.
Elife ; 82019 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-31763979

RESUMO

How two-component genetic systems accumulate evolutionary novelty and diversify in the course of evolution is a fundamental problem in evolutionary systems biology. In the Brassicaceae, self-incompatibility (SI) is a spectacular example of a diversified allelic series in which numerous highly diverged receptor-ligand combinations are segregating in natural populations. However, the evolutionary mechanisms by which new SI specificities arise have remained elusive. Using in planta ancestral protein reconstruction, we demonstrate that two allelic variants segregating as distinct receptor-ligand combinations diverged through an asymmetrical process whereby one variant has retained the same recognition specificity as their (now extinct) putative ancestor, while the other has functionally diverged and now represents a novel specificity no longer recognized by the ancestor. Examination of the structural determinants of the shift in binding specificity suggests that qualitative rather than quantitative changes of the interaction are an important source of evolutionary novelty in this highly diversified receptor-ligand system.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/classificação , Arabidopsis/fisiologia , Variação Genética , Autoincompatibilidade em Angiospermas , Alelos , Arabidopsis/genética , Evolução Molecular , Ligantes , Ligação Proteica , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo
5.
Int J Mol Sci ; 20(13)2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31284391

RESUMO

Self-incompatibility (SI) is a widespread mechanism in angiosperms that prevents inbreeding by rejecting self-pollen. However, the regulation of the SI response in Brassica napus is not well understood. Here, we report that the M-locus protein kinase (MLPK) BnaMLPKs, the functional homolog of BrMLPKs in Brassica rapa, controls SI in B. napus. We identified four paralogue MLPK genes in B. napus, including BnaA3.MLPK, BnaC3.MLPK, BnaA4.MLPK, and BnaC4.MLPK. Two transcripts of BnaA3.MLPK, BnaA3.MLPKf1 and BnaA3.MLPKf2, were generated by alternative splicing. Tissue expression pattern analysis demonstrated that BnaA3.MLPK, especially BnaA3.MLPKf2, is highly expressed in reproductive organs, particularly in stigmas. We subsequently created RNA-silencing lines and CRISPR/Cas9-induced quadruple mutants of BnaMLPKs in B. napus SI line S-70. Phenotypic analysis revealed that SI response is partially suppressed in RNA-silencing lines and is completely blocked in quadruple mutants. These results indicate the importance of BnaMLPKs in regulating the SI response of B. napus. We found that the expression of SI positive regulators S-locus receptor kinase (SRK) and Arm-Repeat Containing 1 (ARC1) are suppressed in bnmlpk mutant, whereas the self-compatibility (SC) element Glyoxalase I (GLO1) maintained a high expression level. Overall, our findings reveal a new regulatory mechanism of MLPK in the SI of B. napus.


Assuntos
Brassica napus/enzimologia , Brassica napus/fisiologia , Proteína Quinase C/metabolismo , Autoincompatibilidade em Angiospermas/fisiologia , Sequência de Aminoácidos , Sequência de Bases , Brassica napus/genética , Sistemas CRISPR-Cas/genética , Edição de Genes , Regulação da Expressão Gênica de Plantas , Mutação/genética , Especificidade de Órgãos/genética , Filogenia , Plantas Geneticamente Modificadas , Polinização , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteína Quinase C/química , Proteína Quinase C/genética , Interferência de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
7.
New Phytol ; 224(1): 505-517, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31254395

RESUMO

A crucial step in the transition from outcrossing to self-fertilization is the loss of genetic self-incompatibility (SI). In the Brassicaceae, SI involves the interaction of female and male specificity components, encoded by the genes SRK and SCR at the self-incompatibility locus (S-locus). Theory predicts that S-linked mutations, and especially dominant mutations in SCR, are likely to contribute to loss of SI. However, few studies have investigated the contribution of dominant mutations to loss of SI in wild plant species. Here, we investigate the genetic basis of loss of SI in the self-fertilizing crucifer species Capsella orientalis, by combining genetic mapping, long-read sequencing of complete S-haplotypes, gene expression analyses and controlled crosses. We show that loss of SI in C. orientalis occurred < 2.6 Mya and maps as a dominant trait to the S-locus. We identify a fixed frameshift deletion in the male specificity gene SCR and confirm loss of male SI specificity. We further identify an S-linked small RNA that is predicted to cause dominance of self-compatibility. Our results agree with predictions on the contribution of dominant S-linked mutations to loss of SI, and thus provide new insights into the molecular basis of mating system transitions.


Assuntos
Capsella/genética , Capsella/fisiologia , Sequência de Bases , Cruzamentos Genéticos , Mutação da Fase de Leitura/genética , Regulação da Expressão Gênica de Plantas , Genes Dominantes , Loci Gênicos , Haplótipos/genética , Filogenia , Característica Quantitativa Herdável , RNA de Plantas/genética , RNA de Plantas/metabolismo , Reprodução/genética , Autoincompatibilidade em Angiospermas/genética , Fatores de Tempo
9.
Plant Mol Biol ; 100(4-5): 367-378, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30937702

RESUMO

KEY MESSAGE: S-RNase was demonstrated to be predominantly recognized by an S locus F-box-like protein and an S haplotype-specific F-box-like protein in compatible pollen tubes of sweet cherry. Self-incompatibility (SI) is a reproductive barrier that rejects self-pollen and inhibits self-fertilization to promote outcrossing. In Solanaceae and Rosaceae, S-RNase-based gametophytic SI (GSI) comprises S-RNase and F-box protein(s) as the pistil and pollen S determinants, respectively. Compatible pollen tubes are assumed to detoxify the internalized cytotoxic S-RNases to maintain growth. S-RNase detoxification is conducted by the Skp1-cullin1-F-box protein complex (SCF) formed by pollen S determinants, S locus F-box proteins (SLFs), in Solanaceae. In Prunus, the general inhibitor (GI), but not pollen S determinant S haplotype-specific F-box protein (SFB), is hypothesized to detoxify S-RNases. Recently, SLF-like proteins 1-3 (SLFL1-3) were suggested as GI candidates, although it is still possible that other proteins function predominantly in GI. To identify the other GI candidates, we isolated four other pollen-expressed SLFL and SFB-like (SFBL) proteins PavSLFL6, PavSLFL7A, PavSFBL1, and PavSFBL2 in sweet cherry. Binding assays with four PavS-RNases indicated that PavSFBL2 bound to PavS1, 6-RNase while the others bound to nothing. PavSFBL2 was confirmed to form an SCF complex in vitro. A co-immunoprecipitation assay using the recombinant PavS6-RNase as bait against pollen extracts and a mass spectrometry analysis identified the SCF complex components of PavSLFLs and PavSFBL2, M-locus-encoded glutathione S-transferase (MGST), DnaJ-like protein, and other minor proteins. These results suggest that SLFLs and SFBLs could act as predominant GIs in Prunus-specific S-RNase-based GSI.


Assuntos
Proteínas F-Box/fisiologia , Proteínas de Plantas/fisiologia , Prunus/metabolismo , Autoincompatibilidade em Angiospermas , Clonagem Molecular , Proteínas F-Box/genética , Proteínas F-Box/metabolismo , Espectrometria de Massas , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Tubo Polínico/metabolismo , Tubo Polínico/fisiologia , Prunus/enzimologia , Reprodução , Ribonucleases/química , Ribonucleases/metabolismo
10.
Plant Biotechnol J ; 17(11): 2184-2198, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31001872

RESUMO

Apple exhibits S-RNase-mediated self-incompatibility. Although the cytotoxic effect of S-RNase inside the self-pollen tube has been studied extensively, the underlying defence mechanism in pollen tube in Rosaceae remains unclear. On exposure to stylar S-RNase, plant defence responses are activated in the pollen tube; however, how these are regulated is currently poorly understood. Here, we show that entry of both self and non-self S-RNase into pollen tubes of apple (Malus domestica) stimulates jasmonic acid (JA) production, in turn inducing the accumulation of MdMYC2 transcripts, a transcription factor in the JA signalling pathway widely considered to be involved in plant defence processes. MdMYC2 acts as a positive regulator in the pollen tube activating expression of MdD1, a gene encoding a defence protein. Importantly, MdD1 was shown to bind to the RNase activity sites of S-RNase leading to inhibition of enzymatic activity. This work provides intriguing insights into an ancient defence mechanism present in apple pollen tubes where MdD1 likely acts as a primary line of defence to inhibit S-RNase cytotoxicity prior to self/non-self recognition.


Assuntos
Malus/genética , Proteínas de Plantas/genética , Tubo Polínico/crescimento & desenvolvimento , Ribonucleases , Autoincompatibilidade em Angiospermas , Tioninas/genética
11.
Mol Biol Rep ; 46(3): 3157-3165, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30963357

RESUMO

Based on the transcriptome data, using RACE techniques, we cloned the full-length EbSRLK1 gene in a medicinal, self-incompatible Asteraceae species, Erigeron breviscapus. Bioinformatics approaches were used to analyze the DNA and protein sequences, physical and chemical properties, and domains of the encoded protein. The full-length EbSRLK1 cDNA is 2891 base pairs (bp) with an open reading frame (ORF) of 2634 bp, which encodes the EbSRLK1 protein with 878 amino acids and an estimated molecular weight of 98.13 kD. The EbSRLK1 protein has the characteristic domain structure of S-locus receptor-like protein kinases, which contains one transmembrane domain but lacks the signal peptide. Quantitative real-time PCR (qRT-PCR) analysis showed that the EbSRLK1 gene is lowly expressed in roots, stems and leaves, but highly expressed in flowers, especially in flowers one day prior to opening. Western blot analysis showed that the EbSRLK1 protein is expressed in stems, leaves, and flowers, but is almost undetectable in roots. The EbSRLK1 protein expression is induced in self-pollinated but not in cross-pollinated E. breviscapus flowers. Cloning and expression analysis of EbSRLK1 lay a solid foundation for elucidating the role of EbSRLK1 in regulating self-incompatibility in E. breviscapus.


Assuntos
Clonagem Molecular , Erigeron/genética , Expressão Gênica , Proteínas de Plantas/genética , Autoincompatibilidade em Angiospermas/genética , Biologia Computacional/métodos , DNA Complementar , Erigeron/metabolismo , Fases de Leitura Aberta , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Estrutura Secundária de Proteína , Análise de Sequência de DNA
12.
Int J Mol Sci ; 20(5)2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30818833

RESUMO

It is clear that the incompatibility system in Fragaria is gametophytic, however, the genetic mechanism behind this remains elusive. Eleven second-generation lines of Fragaria viridis with different compatibility were obtained by manual self-pollination, which can be displayed directly by the level of fruit-set rate. We sequenced two second-generation selfing lines with large differences in fruit-set rate: Ls-S2-53 as a self-incompatible sequencing sample, and Ls-S2-76 as a strong self-compatible sequencing sample. Fragaria vesca was used as a completely self-compatible reference sample, and the genome-wide variations were identified and subsequently annotated. The distribution of polymorphisms is similar on each chromosome between the two sequencing samples, however, the distribution regions and the number of homozygous variations are inconsistent. Expression pattern analysis showed that six candidate genes were significantly associated with self-incompatibility. Using F. vesca as a reference, we focused our attention on the gene FIP2-like (FH protein interacting protein), associated with actin cytoskeleton formation, as the resulting proteins in Ls-S2-53 and Ls-S2-76 have each lost a number of different amino acids. Suppression of FIP2-like to some extent inhibits germination of pollen grains and growth of pollen tubes by reducing F-actin of the pollen tube tips. Our results suggest that the differential distribution of homozygous variations affects F. viridis fruit-set rate and that the fully encoded FIP2-like can function normally to promote F-actin formation, while the new FIP2-like proteins with shortened amino acid sequences have influenced the (in)compatibility of two selfing lines of F. viridis.


Assuntos
Fragaria/genética , Genes de Plantas , Estudos de Associação Genética , Variação Genética , Autoincompatibilidade em Angiospermas/genética , Análise de Sequência de DNA , Sequência de Aminoácidos , Cruzamentos Genéticos , Frutas/genética , Regulação da Expressão Gênica de Plantas , Germinação , Homozigoto , Mutação INDEL/genética , Anotação de Sequência Molecular , Mapeamento Físico do Cromossomo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Tubo Polínico/genética , Tubo Polínico/crescimento & desenvolvimento , Polimorfismo de Nucleotídeo Único/genética
13.
Int Rev Cell Mol Biol ; 343: 1-35, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30712670

RESUMO

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.


Assuntos
Brassicaceae/citologia , Brassicaceae/metabolismo , Pólen/metabolismo , Autoincompatibilidade em Angiospermas , Pólen/citologia , Transdução de Sinais
14.
Nat Plants ; 5(2): 174-183, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30692677

RESUMO

Snapdragon (Antirrhinum majus L.), a member of the Plantaginaceae family, is an important model for plant genetics and molecular studies on plant growth and development, transposon biology and self-incompatibility. Here we report a near-complete genome assembly of A. majus cultivar JI7 (A. majus cv.JI7) comprising 510 Megabases (Mb) of genomic sequence and containing 37,714 annotated protein-coding genes. Scaffolds covering 97.12% of the assembled genome were anchored on eight chromosomes. Comparative and evolutionary analyses revealed that a whole-genome duplication event occurred in the Plantaginaceae around 46-49 million years ago (Ma). We also uncovered the genetic architectures associated with complex traits such as flower asymmetry and self-incompatibility, identifying a unique duplication of TCP family genes dated to around 46-49 Ma and reconstructing a near-complete ψS-locus of roughly 2 Mb. The genome sequence obtained in this study not only provides a representative genome sequenced from the Plantaginaceae but also brings the popular plant model system of Antirrhinum into the genomic age.


Assuntos
Antirrhinum/genética , Genoma de Planta , Proteínas de Plantas/genética , Evolução Biológica , Flores/anatomia & histologia , Flores/genética , Flores/fisiologia , Duplicação Gênica , Anotação de Sequência Molecular , Filogenia , Autoincompatibilidade em Angiospermas/genética
15.
Int J Mol Sci ; 20(3)2019 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-30696008

RESUMO

This study explicates molecular insights commencing Self-Incompatibility (SI) and CC (cross-compatibility/fertilization) in self (SP) and cross (CP) pollinated pistils of tea. The fluorescence microscopy analysis revealed ceased/deviated pollen tubes in SP, while successful fertilization occurred in CP at 48 HAP. Global transcriptome sequencing of SP and CP pistils generated 109.7 million reads with overall 77.9% mapping rate to draft tea genome. Furthermore, concatenated de novo assembly resulted into 48,163 transcripts. Functional annotations and enrichment analysis (KEGG & GO) resulted into 3793 differentially expressed genes (DEGs). Among these, de novo and reference-based expression analysis identified 195 DEGs involved in pollen-pistil interaction. Interestingly, the presence of 182 genes [PT germination & elongation (67), S-locus (11), fertilization (43), disease resistance protein (30) and abscission (31)] in a major hub of the protein-protein interactome network suggests a complex signaling cascade commencing SI/CC. Furthermore, tissue-specific qRT-PCR analysis affirmed the localized expression of 42 DE putative key candidates in stigma-style and ovary, and suggested that LSI initiated in style and was sustained up to ovary with the active involvement of csRNS, SRKs & SKIPs during SP. Nonetheless, COBL10, RALF, FERONIA-rlk, LLG and MAPKs were possibly facilitating fertilization. The current study comprehensively unravels molecular insights of phase-specific pollen-pistil interaction during SI and fertilization, which can be utilized to enhance breeding efficiency and genetic improvement in tea.


Assuntos
Camellia sinensis/genética , Camellia sinensis/fisiologia , Fertilização/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Tubo Polínico/genética , Autoincompatibilidade em Angiospermas/genética , Transcrição Genética , Ontologia Genética , Anotação de Sequência Molecular , Especificidade de Órgãos/genética , Tubo Polínico/crescimento & desenvolvimento , Polinização , Mapas de Interação de Proteínas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reprodutibilidade dos Testes , Análise de Sequência de RNA
16.
Int J Mol Sci ; 20(1)2019 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-30626063

RESUMO

Self-incompatibility (SI) is a complex process, one out of several mechanisms that prevent plants from self-fertilizing to maintain and increase the genetic variability. This process leads to the rejection of the male gametophyte and requires the co-participation of numerous molecules. Plants have evolved two distinct SI systems, the sporophytic (SSI) and the gametophytic (GSI) systems. The two SI systems are markedly characterized by different genes and proteins and each single system can also be divided into distinct subgroups; whatever the mechanism, the purpose is the same, i.e., to prevent self-fertilization. In Malinae, a subtribe in the Rosaceae family, i.e., Pyrus communis and Malus domestica, the GSI requires the production of female determinants, known as S-RNases, which penetrate the pollen tube to interact with the male determinants. Beyond this, the penetration of S-RNase into the pollen tube triggers a series of responses involving membrane proteins, such as phospholipases, intracellular variations of cytoplasmic Ca2+, production of reactive oxygen species (ROS) and altered enzymatic activities, such as that of transglutaminase (TGase). TGases are widespread enzymes that catalyze the post-translational conjugation of polyamines (PAs) to different protein targets and/or the cross-linking of substrate proteins leading to the formation of cross-linked products with high molecular mass. When actin and tubulin are the substrates, this destabilizes the cytoskeleton and inhibits the pollen-tube's growth process. In this review, we will summarize the current knowledge of the relationship between S-RNase penetration, TGase activity and cytoskeleton function during GSI in the Malinae.


Assuntos
Citoesqueleto/metabolismo , Células Germinativas Vegetais/fisiologia , Rosaceae/metabolismo , Autoincompatibilidade em Angiospermas/fisiologia , Transglutaminases/metabolismo , Tubo Polínico/crescimento & desenvolvimento
17.
Curr Biol ; 29(3): 506-512.e4, 2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-30661797

RESUMO

Self-incompatibility (SI) is a genetic mechanism in hermaphroditic flowers that prevents inbreeding by rejection of self-pollen, while allowing cross- or genetically diverse pollen to germinate on the stigma to successfully fertilize the ovules. In Brassica, SI is initiated by the allele-specific recognition of pollen-encoded, secreted ligand (SCR/SP11) by the stigmatic receptor kinase S-locus receptor kinase (SRK), resulting in activation of SRK through phosphorylation [1-3]. Once activated, this phospho-relay converges on intracellular compatibility factors, which are immediately targeted for degradation by the E3 ligase, ARC1, resulting in the pollen rejection response [4, 5]. Through proteomics approach using proteins from SI activated stigmas of Brassica napus, we identified phospholipase D α1 (PLDα1) as one of the candidates that is most likely targeted for degradation after SI [6]. PLDα1 is enriched in the stigmas and functions as a stigmatic compatibility factor as loss of PLDα1 compromised compatible pollination, while overexpression of PLDα1 in self-incompatible stigmas led to breakdown of SI response. PLDα1 can be ubiquitinated by ARC1 and accumulate in ARC1-suppressed lines, confirming PLDα1 as a target of ARC1 during SI response. Addition of phosphatidic acid (PA) to PLDα1-deficient stigmas was sufficient to rescue compatibility, suggesting an essential role for PA generated by PLDα1 for compatible interactions. We propose that PA produced by PLDα1 activity during compatible pollination promotes vesicle fusion at the membrane to facilitate exocytosis necessary for pollen germination to occur, while SI response could abrogate this process by targeting PLDα1 for degradation.


Assuntos
Brassica napus/fisiologia , Flores/fisiologia , Fosfolipase D/genética , Proteínas de Plantas/genética , Autoincompatibilidade em Angiospermas/genética , Brassica napus/genética , Flores/genética , Regulação da Expressão Gênica de Plantas , Fosfolipase D/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/fisiologia
18.
New Phytol ; 221(1): 553-564, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29992588

RESUMO

Selection to prevent interspecific mating can cause an increase or a decrease in self-pollination in sympatric populations. Characterizing the geographical variation in self and interspecific incompatibilities within a species can reveal if and how the evolution of self and interspecific mate choice are linked. We used controlled pollinations to characterize the variation in self and interspecific incompatibility across 29 populations of Phlox drummondii. We evaluated seed set from these pollinations and described the developmental timing of variation in pollen-pistil compatibility. There is extensive quantitative variation in self-incompatibility and interspecific-incompatibility with its close congener P. cuspidata. Phlox drummondii populations that co-occur and hybridize with P. cuspidata have significantly higher interspecific incompatibility and self-incompatibility than geographically isolated P. drummondii populations. The strength of self and interspecific incompatibility is significantly correlated among individuals and the strength of both incompatibilities is explained by the success of pollen adhesion to the stigma. The correlated strength of self and interspecific incompatibility across the range of P. drummondii and the concurrent developmental timing of the pollen-pistil interaction, suggests these incompatibilities have an overlapping molecular mechanism. The geographical distribution of variation in incompatibilities indicates that this mechanistic link between incompatibilities may affect the evolution of mate choice in plants.


Assuntos
Evolução Biológica , Magnoliopsida/fisiologia , Autoincompatibilidade em Angiospermas , Flores/fisiologia , Hibridização Genética , Pólen , Polinização , Simpatria , Texas
19.
Biomol NMR Assign ; 13(1): 67-70, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30284185

RESUMO

The SPH proteins are a large family of small, disulphide-bonded, secreted proteins, originally found to be involved in the self-incompatibility response in the field poppy (Papaver rhoeas). They are now known to be widely distributed in plants, many containing multiple members of this protein family. Apart from the PrsS proteins in Papaver the function of these proteins is unknown but they are thought to be involved in plant development and cell signalling. There has been no structural study of SPH proteins to date. Using the Origami strain of E. coli, we cloned and expressed one member of this family, SPH15 from Arabidopsis thaliana, as a folded thioredoxin-fusion protein, purified it from the cytosol, and cleaved it to obtain the secreted protein. We here report the assignment of the NMR spectra of SPH15, which contains 112 residues plus three N-terminal amino acids from the vector. The secondary structure propensity from TALOS+ shows that it contains eight beta strands and connecting loops. This is largely in agreement with predictions from the amino acid sequence, which show an additional C-terminal strand.


Assuntos
Proteínas de Arabidopsis/química , Arabidopsis/química , Ressonância Magnética Nuclear Biomolecular , Autoincompatibilidade em Angiospermas , Homologia de Sequência de Aminoácidos , Isótopos de Carbono , Isótopos de Nitrogênio , Estrutura Secundária de Proteína , Prótons
20.
BMC Plant Biol ; 18(1): 323, 2018 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-30509158

RESUMO

BACKGROUND: Observations of precocious (early bearing) genotypes of walnut (Juglans regia L.) under natural conditions encouraged us to study the origin and genetic control of these fascinating traits. RESULTS: In this study, the self-fertility, progeny performance, and simple sequence repeat (SSR) locus variation of iron walnut (Juglans sigillata Dode), an ecotype of J. regia, were investigated. The average self-pollinated fruit set rate of J. sigillata cv. 'Dapao' (DP) was 7.0% annually from 1979 to 1982. The average germination rate of self-pollinated seeds was 45.2% during the 4-year period. Most progeny had inbreeding depression. Nine representative self-pollinated progeny (SP1-SP9), with special or typical traits of DP, were selected. SP1-SP4 were precocious because they initiated flowers as early as 2 years after germination, compared to the 7-10-yr period that is typical of DP. SP9 had not flowered since 1980. Twelve SSR markers were used to analyze the SP and DP. The genome of SP had a tendency toward high levels of homozygosity. The high levels of homozygosity reported in 18 additional precocious walnut genotypes complemented the results of this study. CONCLUSIONS: These results provide evidence of precocious phenotypes and genomes with high levels of homozygosity that might be generated from self-pollinating walnut. This suggests that self-pollination might facilitate the generation of unique homozygous parents for subsequent use in walnut-breeding programs. The results also indicate that more attention should be focused on adequate management of precocious walnut to avoid early depression in the production of nuts.


Assuntos
Homozigoto , Juglans/genética , Polinização/genética , Estudos de Associação Genética , Genótipo , Juglans/fisiologia , Repetições de Microssatélites/genética , Polinização/fisiologia , Autoincompatibilidade em Angiospermas/genética
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