self-incompatibility Dotaz Zobrazit nápovědu
In Brassica species, self-incompatibility has been mapped genetically to a single chromosomal location. In this region several closely linked genes have been identified. One of them, S-locus receptor kinase (SRK), determines S haplotype specificity of the stigma and it's the key protein for SI reaction. The role of the S locus glycoprotein (SLG) gene remains unclear. In the last decade approximately 15 additional genes linked to S-locus have been found. Recently, a gene has been identified (SCR) that encodes a small cysteine-rich protein which is a candidate for the pollen ligand. In addition to S locus linked genes there are unlinked SLRgenes (S-locus related genes). In this review, we discuss the role of these genes and the current view on the self-incompatibility mechanism in Brassica.
- MeSH
- biologické modely MeSH
- Brassica genetika růst a vývoj MeSH
- glykoproteiny genetika MeSH
- mapování chromozomů MeSH
- molekulární sekvence - údaje MeSH
- proteinkinasy genetika MeSH
- pyl růst a vývoj MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika MeSH
- sekvence aminokyselin MeSH
- sekvenční homologie aminokyselin MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- glykoproteiny MeSH
- proteinkinasy MeSH
- rostlinné proteiny MeSH
- S-receptor kinase MeSH Prohlížeč
- SCR protein, Brassica oleracea MeSH Prohlížeč
- self-incompatibility locus specific glycoprotein, Brassica MeSH Prohlížeč
Balancing selection is a form of natural selection maintaining diversity at the sites it targets and at linked nucleotide sites. Due to selection favoring heterozygosity, it has the potential to facilitate the accumulation of a "sheltered" load of tightly linked recessive deleterious mutations. However, precisely evaluating the extent of these effects has remained challenging. Taking advantage of plant self-incompatibility as one of the best-understood examples of long-term balancing selection, we provide a highly resolved picture of the genomic extent of balancing selection on the sheltered genetic load. We used targeted genome resequencing to reveal polymorphism of the genomic region flanking the self-incompatibility locus in three sample sets in each of the two closely related plant species Arabidopsis halleri and Arabidopsis lyrata, and used 100 control regions from throughout the genome to factor out differences in demographic histories and/or sample structure. Nucleotide polymorphism increased strongly around the S-locus in all sample sets, but only over a limited genomic region, as it became indistinguishable from the genomic background beyond the first 25-30 kb. Genes in this chromosomal interval exhibited no excess of mutations at 0-fold degenerated sites relative to putatively neutral sites, hence revealing no detectable weakening of the efficacy of purifying selection even for these most tightly linked genes. Overall, our results are consistent with the predictions of a narrow genomic influence of linkage to the S-locus and clarify how natural selection in one genomic region affects the evolution of the adjacent genomic regions.
- Klíčová slova
- Arabidopsis, S-locus, balancing selection, deleterious mutations, linked selection, self-incompatibility, sheltered genetic load,
- MeSH
- Arabidopsis * genetika MeSH
- genetická zátěž MeSH
- nukleotidy MeSH
- polymorfismus genetický MeSH
- selekce (genetika) MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- nukleotidy MeSH
The interactions between mitochondria and nucleus substantially influence plant development, stress response and morphological features. The prominent example of a mitochondrial-nuclear interaction is cytoplasmic male sterility (CMS), when plants produce aborted anthers or inviable pollen. The genes responsible for CMS are located in mitochondrial genome, but their expression is controlled by nuclear genes, called fertility restorers. Recent explosion of high-throughput sequencing methods enabled to study transcriptomic alterations in the level of non-coding RNAs under CMS biogenesis. We summarize current knowledge of the role of nucleus encoded regulatory non-coding RNAs (long non-coding RNA, microRNA as well as small interfering RNA) in CMS. We also focus on the emerging data of non-coding RNAs encoded by mitochondrial genome and their possible involvement in mitochondrial-nuclear interactions and CMS development.
- Klíčová slova
- cytoplasmic male sterility, gene expression, global transcriptome, non-coding RNA, pollen development,
- MeSH
- autoinkompatibilita krytosemenných rostlin genetika MeSH
- Magnoliopsida fyziologie MeSH
- mitochondriální geny MeSH
- nekódující RNA genetika metabolismus MeSH
- neplodnost rostlin genetika MeSH
- pyl genetika fyziologie MeSH
- rostlinné geny MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- nekódující RNA MeSH
The sweet cherry plant (Prunus avium L.) is primarily self-incompatible, with so-called S-alleles responsible for the inability of flowers to be pollinated not only by their own pollen grains but also by pollen from other cherries having the same S-alleles. This characteristic has wide-ranging impacts on commercial growing, harvesting, and breeding. However, mutations in S-alleles as well as changes in the expression of M locus-encoded glutathione-S-transferase (MGST) can lead to complete or partial self-compatibility, simplifying orchard management and reducing possible crop losses. Knowledge of S-alleles is important for growers and breeders, but current determination methods are challenging, requiring several PCR runs. Here we present a system for the identification of multiple S-alleles and MGST promoter variants in one-tube PCR, with subsequent fragment analysis on a capillary genetic analyzer. The assay was shown to unequivocally determine three MGST alleles, 14 self-incompatible S-alleles, and all three known self-compatible S-alleles (S3', S4', S5') in 55 combinations tested, and thus it is especially suitable for routine S-allele diagnostics and molecular marker-assisted breeding for self-compatible sweet cherries. In addition, we identified a previously unknown S-allele in the 'Techlovicka´ genotype (S54) and a new variant of the MGST promoter with an 8-bp deletion in the ´Kronio´ cultivar.
- Klíčová slova
- M locus-encoded glutathione-S-transferase, MAS, MGST, S-allele, fragment analysis, molecular marker assisted breeding, self-compatibility, self-incompatibility, sweet cherry,
- MeSH
- alely MeSH
- polymerázová řetězová reakce MeSH
- Prunus avium * genetika MeSH
- šlechtění rostlin MeSH
- slivoň * genetika MeSH
- Publikační typ
- časopisecké články MeSH
The selection of desirable genotypes with recessive characteristics, such as self-incompatible plants, is often difficult or even impossible and represents a crucial barrier in accelerating the breeding process. Molecular approaches and selection based on molecular markers can allow breeders to overcome this limitation. The use of self-incompatibility is an alternative in hybrid breeding of oilseed rape. Unfortunately, stable self-incompatibility is recessive and phenotype-based selection is very difficult and time-consuming. The development of reliable molecular markers for detecting desirable plants with functional self-incompatible genes is of great importance for breeders and allows selection at early stages of plant growth. Because most of these reliable molecular markers are based on discrimination of class I S-locus genes that are present in self-compatible plants, there is a need to use an internal control in order to detect possible PCR inhibition that gives false results during genotyping. In this study, 269 double haploid F2 oilseed rape plants obtained by microspore embryogenesis were used to verify the applicability of an improved PCR assay based on the detection of the class I SLG gene along with an internal control. Comparative analysis of the PCR genotyping results vs. S phenotype analysis confirmed the applicability of this molecular approach in hybrid breeding programs. This approach allows accurate detection of self-incompatible plants via a different amplification profile.
- Klíčová slova
- MAS, S locus, SLG, double haploid, hybrid breeding,
- Publikační typ
- časopisecké články MeSH
Studying the consequences of hybridization on plant performance is insightful to understand the adaptive potential of populations, notably at local scales. Due to reduced effective recombination, predominantly selfing species are organized in highly homozygous multi-locus-genotypes (or lines) that accumulate genetic differentiation both among- and within-populations. This high level of homozygosity facilitates the dissection of the genetic basis of hybrid performance in highly selfing species, which gives insights into the mechanisms of reproductive isolation between lines. Here, we explored the fitness consequences of hybridization events between natural inbred lines of the predominantly selfing species Medicago truncatula, at both within- and among-populations scales. We found that hybridization has opposite effects pending on studied fitness proxies, with dry mass showing heterosis, and seed production showing outbreeding depression. Although we found significant patterns of heterosis and outbreeding depression, they did not differ significantly for within- compared to among-population crosses. Family-based analyses allowed us to determine that hybrid differentiation was mostly due to dominance and epistasis. Dominance and/or dominant epistatic interactions increased dry mass, while decreasing seed production, and recessive epistatic interactions mostly had a positive effect on both fitness proxies. Our results illustrate how genetic incompatibilities can accumulate at a very local scale among multi-locus-genotypes, and how non-additive genetic effects contribute to heterosis and outbreeding depression.
Design and preparation of functional nanomaterials with specific properties requires precise control over their microscopic structure. A prototypical example is the self-assembly of diblock copolymers, which generate highly ordered structures controlled by three parameters: the chemical incompatibility between blocks, block size ratio and chain length. Recent advances in polymer synthesis have allowed for the preparation of gradient copolymers with controlled sequence chemistry, thus providing additional parameters to tailor their assembly. These are polydisperse monomer sequence, block size distribution and gradient strength. Here, we employ dissipative particle dynamics to describe the self-assembly of gradient copolymer melts with strong, intermediate, and weak gradient strength and compare their phase behavior to that of corresponding diblock copolymers. Gradient melts behave similarly when copolymers with a strong gradient are considered. Decreasing the gradient strength leads to the widening of the gyroid phase window, at the expense of cylindrical domains, and a remarkable extension of the lamellar phase. Finally, we show that weak gradient strength enhances chain packing in gyroid structures much more than in lamellar and cylindrical morphologies. Importantly, this work also provides a link between gradient copolymers morphology and parameters such as chemical incompatibility, chain length and monomer sequence as support for the rational design of these nanomaterials.
- Klíčová slova
- block copolymers, dissipative particle dynamics, gradient copolymers, gradient strength, microphase separation, nanomaterials, self-assembly,
- Publikační typ
- časopisecké články MeSH
Block copolymers spontaneously self-assemble into nanostructured morphologies with industrially attractive properties; however, the relationships between polymer architecture and self-assembled morphology are difficult to tailor for copolymers with increased conformational restrictions. Using Dissipative Particle Dynamics, the self-assembled morphology of comb- and star-shaped diblock copolymers was simulated as a function of the number of arms, arm length, weight fraction, and A-B incompatibility. As the number of arms on the star, or grafting points for the comb, was increased from three to four to six, the ability to self-assemble into ordered morphologies was restricted. The molecular bridging between adjacent ordered domains was observed for both comb- and star-shaped copolymers, which was found to be enhanced with increasing number of arms. This study illustrates that comb- and star-shaped copolymers are viable alternatives for applications that would benefit from highly bridged nanostructural domains.
- Publikační typ
- časopisecké články MeSH
One of the most fundamental, although controversial, questions related to the evolution of plant mating systems is the distribution of outcrossing rates. Self-compatibility, and especially autonomous self-pollination, can become particularly beneficial in anthropogenically degraded habitats with impoverished pollinator assemblages and increased pollen limitation. In a hand-pollination experiment with 46 meadow plants from the Železné hory Mts., Czech Republic, we evaluated the species' ability to adopt different mating systems. For a subset of the species, we also tested seed germination for inbreeding depression. Subsequently, we analysed relationships between the species' mating systems and 12 floral and life-history traits. We found a relatively discrete distribution of the studied species into four groups. Fully and partially self-incompatible species formed the largest group, followed by self-compatible non-selfers and mixed mating species. The germination experiment showed an absence of inbreeding depression in 19 out of 22 examined species. Nectar sugar per flower, nectar sugar per shoot and dichogamy were significant associated with the mating system. Spontaneous selfing ability and self-incompatibility in species of the meadow communities had a discrete distribution, conforming to the general distribution of mating and breeding systems in angiosperms. The low frequency of spontaneous selfers and the lack of inbreeding depression at germination suggest the existence of a selection against selfing at the later ontogenetic stages. Some floral traits, such as the level of dichogamy and amount of nectar reward, may strongly impact the balance between selfing and outcrossing rates in the self-compatible species and thus shape the evolution of mating systems.
- Klíčová slova
- Autonomous selfing, floral traits, hand-pollination, inbreeding depression, meadows, self-compatibility,
- MeSH
- fyziologie rostlin * MeSH
- květy MeSH
- opylení * MeSH
- pastviny * MeSH
- rozmnožování fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
Polyploidy, or whole-genome duplication, is a common speciation mechanism in plants. An important barrier to polyploid establishment is a lack of compatible mates. Because self-compatibility alleviates this problem, it has long been hypothesized that there should be an association between polyploidy and self-compatibility (SC), but empirical support for this prediction is mixed. Here, we investigate whether the molecular makeup of the Brassicaceae self-incompatibility (SI) system, and specifically dominance relationships among S-haplotypes mediated by small RNAs, could facilitate loss of SI in allopolyploid crucifers. We focus on the allotetraploid species Capsella bursa-pastoris, which formed ~300 kya by hybridization and whole-genome duplication involving progenitors from the lineages of Capsella orientalis and Capsella grandiflora. We conduct targeted long-read sequencing to assemble and analyze eight full-length S-locus haplotypes, representing both homeologous subgenomes of C. bursa-pastoris. We further analyze small RNA (sRNA) sequencing data from flower buds to identify candidate dominance modifiers. We find that C. orientalis-derived S-haplotypes of C. bursa-pastoris harbor truncated versions of the male SI specificity gene SCR and express a conserved sRNA-based candidate dominance modifier with a target in the C. grandiflora-derived S-haplotype. These results suggest that pollen-level dominance may have facilitated loss of SI in C. bursa-pastoris. Finally, we demonstrate that spontaneous somatic tetraploidization after a wide cross between C. orientalis and C. grandiflora can result in production of self-compatible tetraploid offspring. We discuss the implications of this finding on the mode of formation of this widespread weed.
