EQUILIBRIUM FREQUENCIES OF SPOROPHYTIC SELF-INCOMPATIBILITY ALLELES

1974 ◽  
Vol 16 (3) ◽  
pp. 611-618 ◽  
Author(s):  
D. R. Sampson
Keyword(s):  
Computer Program ◽  
Numerical Solutions ◽  
Deterministic Model ◽  
Self Incompatibility ◽  
Large Measure ◽  
Large Numbers ◽  
S Alleles ◽  
Equilibrium Approach ◽  
Dominance Level ◽  
Incompatibility Alleles

A deterministic model (Fortran computer program) was used to compute equilibrium frequencies of multiple S alleles The model permitted various numbers of alleles at three dominance levels in the pollen and with independent allele action in the stigma. Numerical solutions showed that the frequency of alleles at any one dominance level depends, in large measure, on the evenness with which the alleles are distributed among the three levels. The smaller the proportion at any one level, the greater the frequency per allele at that level. This is termed the "small number effect." It enables dominant alleles to become more frequent than recessive alleles.Recessive alleles are the more frequent at equilibrium when the dominance levels have equal numbers of alleles. The magnitude of this "recessive effect" diminishes rapidly as the number of alleles in the population is increased. Thus, its importance is less than that suggested by the previously solved cases with one or two alleles per level.With very large numbers of alleles in the population, the genotypic class frequencies at equilibrium approach frequencies generated by a modified use of the Hardy-Weinberg law. All alleles arrive at the same frequency at this limit, regardless of dominance or distribution along the dominance sequence.

scholarly journals Self-incompatibility allele identification in Ukrainian sweet cherry (Prunus avium L.) cultivars

2018 ◽  
Vol 15 (2) ◽  
pp. 150-158
Author(s):  
Ya. I. Ivanovych ◽  
N. V. Tryapitsyna ◽  
K. M. Udovychenko ◽  
R. A. Volkov
Keyword(s):  
Sweet Cherry ◽  
Prunus Avium ◽  
Electrophoretic Analysis ◽  
Self Incompatibility ◽  
Incompatibility Group ◽  
S Alleles ◽  
Pcr Products ◽  
Incompatibility Alleles ◽  
Sweet Cherry Cultivars ◽  
Consensus Primers

Aim. Ukrainian breeders have created a large number of sweet cherry cultivars, which still remain almost unexplored at the molecular level. The aim of our study was to identify the self-incompatibility alleles (S-alleles) in Ukrainian sweet cherry cultivars and landraces, and to elucidate, to which cross-incompatibility group the cultivars belong. Methods. The PCR was conducted using consensus primers to the first and second introns of S-RNAse gene and to the single intron of SFB gene. The electrophoretic analysis of the PCR products of the second intron of S-RNAse was carried out in agarose gel, whereas detection of fluorescently labeled DNA fragments of the first S-RNAse intron and the SFB intron was performed using a genetic analyzer. Results. The S-alleles of 25 Ukrainian sweet cherry cultivars and 10 landraces were identified. The S-alleles frequencies and affiliation of cultivars and landraces to the groups of cross-incompatibility were determined. The obtained data can be used in breeding programs and by planning of industrial plantings. Conclusions. In the study, 12 different S-alleles and 79 S-haplotypes were identified. The S1, S3, S4, S5, S6 and S9 alleles are the most widespread among Ukrainian sweet cherry cultivars and landraces. The high frequencies of S5 and especially of S9 alleles are characteristic for the Ukrainian cultivars and distinguish them from other European ones. For the Ukrainian sweet cherry cultivars, the XXXVII (S5S9) cross-incompatibility group appeared to be the most numerous.Keywords: Ukrainian sweet cherry cultivars, S-locus, Sgenotypes, self- and cross-incompatibility, Prunus avium.

scholarly journals Nonself-recognition-based self-incompatibility can alternatively promote or prevent introgression

2020 ◽  
Author(s):  
Alexander Harkness ◽  
Yaniv Brandvain
Keyword(s):  
Pollen Limitation ◽  
List Type ◽  
Self Incompatibility ◽  
Core Eudicots ◽  
S Alleles ◽  
Self Fertilization ◽  
Nonself Recognition ◽  
Negative Frequency Dependent Selection ◽  
Incompatibility Alleles ◽  
S Allele

1SummaryTraditionally, we expect that self-incompatibility alleles (S-alleles), which prevent self-fertilization, should benefit from negative-frequency dependent selection and rise to high frequency when introduced to a new population through gene flow. However, the most taxonomically widespread form of self-incompatibility, the ribonuclease-based system ancestral to the core eudicots, functions through nonself-recognition, which drastically alters the process of S-allele diversification.We analyze a model of S-allele evolution in two populations connected by migration, focusing on comparisons among the fates of S-alleles originally unique to each population and those shared among populations.We find that both shared and unique S-alleles originating from the population with more unique S-alleles were usually fitter than S-alleles from the population with fewer. Resident S-alleles were often driven extinct and replaced by migrant S-alleles, though this outcome could be averted by pollen limitation or biased migration.Nonself-recognition-based self-incompatibility will usually either disfavor introgression of S-alleles or result in the whole-sale replacement of S-alleles from one population with those from another.

scholarly journals Base-Pairing Requirements for Small RNA-Mediated Gene Silencing of Recessive Self-Incompatibility Alleles in Arabidopsis halleri

Genetics ◽  
2020 ◽  
Vol 215 (3) ◽  
pp. 653-664
Author(s):  
Nicolas Burghgraeve ◽  
Samson Simon ◽  
Simon Barral ◽  
Isabelle Fobis-Loisy ◽  
Anne-Catherine Holl ◽  
...  
Keyword(s):  
Dominance Hierarchy ◽  
Self Incompatibility ◽  
Arabidopsis Halleri ◽  
Base Pairing ◽  
Transcript Levels ◽  
Small Noncoding Rnas ◽  
Target Sites ◽  
S Alleles ◽  
Allele Specific ◽  
Incompatibility Alleles

Small noncoding RNAs are central regulators of genome activity and stability. Their regulatory function typically involves sequence similarity with their target sites, but understanding the criteria by which they specifically recognize and regulate their targets across the genome remains a major challenge in the field, especially in the face of the diversity of silencing pathways involved. The dominance hierarchy among self-incompatibility alleles in Brassicaceae is controlled by interactions between a highly diversified set of small noncoding RNAs produced by dominant S-alleles and their corresponding target sites on recessive S-alleles. By controlled crosses, we created numerous heterozygous combinations of S-alleles in Arabidopsis halleri and developed an real-time quantitative PCR assay to compare allele-specific transcript levels for the pollen determinant of self-incompatibility (SCR). This provides the unique opportunity to evaluate the precise base-pairing requirements for effective transcriptional regulation of this target gene. We found strong transcriptional silencing of recessive SCR alleles in all heterozygote combinations examined. A simple threshold model of base pairing for the small RNA–target interaction captures most of the variation in SCR transcript levels. For a subset of S-alleles, we also measured allele-specific transcript levels of the determinant of pistil specificity (SRK), and found sharply distinct expression dynamics throughout flower development between SCR and SRK. In contrast to SCR, both SRK alleles were expressed at similar levels in the heterozygote genotypes examined, suggesting no transcriptional control of dominance for this gene. We discuss the implications for the evolutionary processes associated with the origin and maintenance of the dominance hierarchy among self-incompatibility alleles.

scholarly journals Base-pairing requirements for small RNA-mediated gene silencing of recessive self-incompatibility alleles in Arabidopsis halleri

2018 ◽  
Author(s):  
N. Burghgraeve ◽  
S. Simon ◽  
S. Barral ◽  
I. Fobis-Loisy ◽  
A-C Holl ◽  
...  
Keyword(s):  
Dominance Hierarchy ◽  
Self Incompatibility ◽  
Arabidopsis Halleri ◽  
Base Pairing ◽  
Transcript Levels ◽  
Target Sites ◽  
S Alleles ◽  
Allele Specific ◽  
Incompatibility Alleles ◽  
Non Coding Rnas

AbstractSmall non-coding RNAs are central regulators of genome activity and stability. Their regulatory function typically involves sequence similarity with their target sites, but understanding the criteria by which they specifically recognize and regulate their targets across the genome remains a major challenge in the field, especially in the face of the diversity of silencing pathways involved. The dominance hierarchy among self-incompatibility alleles in Brassicaceae is controlled by interactions between a highly diversified set of small non-coding RNAs produced by dominant S-alleles and their corresponding target sites on recessive S-alleles. By controlled crosses, we created numerous heterozygous combinations of S-alleles in Arabidopsis halleri and developed an RT-qPCR assay to compare allele-specific transcript levels for the pollen determinant of self-incompatibility (SCR). This provides the unique opportunity to evaluate the precise base-pairing requirements for effective transcriptional regulation of this target gene. We found strong transcriptional silencing of recessive SCR alleles in all heterozygote combinations examined. A simple threshold model of base-pairing for the sRNA-target interaction captures most of the variation in SCR transcript levels. For a subset of S-alleles, we also measured allele-specific transcript levels of the determinant of pistil specificity (SRK) and found sharply distinct expression dynamics throughout flower development between SCR and SRK. In contrast to SCR, both SRK alleles were expressed at similar levels in the heterozygote genotypes examined, suggesting no transcriptional control of dominance for this gene. We discuss the implications for the evolutionary processes associated with the origin and maintenance of the dominance hierarchy among self-incompatibility alleles.

scholarly journals Detecting and determining self-incompatibility alleles in almond genotypes using molecular method.

2019 ◽  
Author(s):  
Sorush Niknamian
Keyword(s):  
The Self ◽  
Self Incompatibility ◽  
Base Pairs ◽  
Inhibitory System ◽  
S Alleles ◽  
Study Population ◽  
Incompatibility Alleles ◽  
Pcr Method ◽  
Polymerase Chain ◽  
New Alleles

Abstract One of the problems in almond production is self-incompatibility in this plant, which is considered as an important improvement point for this tree. Self-incompatibility causes non-uniformity and garden management problems. Most cultivars of almonds have gametophytic self-incompatibility that is controlled by a multi-allelic gene site. The inoculation inhibitor factor in this inhibitory system is the stop of pollen tube growth in the style. This study aims to detect and determine the self-compatible genotype from among the studied samples and determine the self-incompatibility alleles in the studied masses. For the experiment, the leaf samples were collected from 100 almond genotypes that had good products in recent years. The DNA of young leaf samples in these genotypes was extracted using Gept and Celeg (1989) method with a few changes. Today, various methods have been invented for detecting the genotypes and self-compatible cultivars from selfincompatible cultivars as well as S alleles in almonds, including the PCR method. Therefore, in order to detect S alleles in different almond and some hybrid genotypes, the exclusive primer pairs, including AS1II-AmyC5R, ConF-ConR and Cebador2-Cebador8, were used in the polymerase chain reaction. All of the primers have been used by other researchers to detect almond alleles and the effectiveness of these pairs of primers was confirmed in this experiment. Using the AS1IIAmyC5R and Cebador2-Cebador8 primers, the Sf allele with the size of 1200 base pairs was detected. Using the ConF-ConR pair of primer, the S1, S2, S3, S10, S11, S23, and S31 alleles were detected in the self-incompatible samples. Using AS1II-AmyC5R pair of primer, the known alleles of S3, Sf, S2, S1, S5, S10, S11, S23, and S13 were detected. The other bands obtained from the PCR were related to the known self-incompatibility alleles that might be considered as new alleles. In the study population in this research, S1, S2, S3, and S11 alleles had higher frequency.

Assessment of Mating System in Helianthus annuus and H. petiolaris (Asteraceae) Populations

Helia ◽  
2020 ◽  
Vol 43 (72) ◽  
pp. 15-32
Author(s):  
Agustina Gutierrez ◽  
Daiana Scaccia Baffigi ◽  
Monica Poverene
Keyword(s):  
Gene Flow ◽  
Helianthus Annuus ◽  
Genetic System ◽  
The Self ◽  
Self Incompatibility ◽  
S Alleles ◽  
Self Fertilization ◽  
Self Compatibility ◽  
Incompatibility Alleles ◽  
Crop Area

AbstractHelianthus annuus subsp. annuus and H. petiolaris are wild North American species that have been naturalized in central Argentina. They have a sporophytic self-incompatibility genetic system that prevent self-fertilization but the occurrence of self-compatible plants in Argentina was observed in both species and could in part explain their highly invasive ability. Their geographical distribution coincides with the major crop area. The domestic sunflower is self-compatible, can hybridize with both species and presents a considerable amount of gene flow. The aim of this study is to understand the self-incompatibility mechanism in both wild Helianthus species. Reciprocal crossing and seed production were used to identify self-compatible genotypes, the number and distribution of self-incompatibility alleles within populations and the type and extent of allelic interactions in the pollen and pistil. The behaviour of S alleles within each population was explained by five functional S alleles and one non-functional allele in each species, differing in their presence and frequency within accessions. In both species, the allelic interactions were of dominance/recessiveness and codominance in pollen, whereas it was only codominance in the pistil. Inbreeding effects in wild materials appeared in the third generation of self-pollination, with lethal effects in most plants. The number of S alleles is low and they behave in a similar way of other Asteraceae species. The self-compatibility was addressed to non-functional S alleles introgressed in wild Helianthus plants through gene flow from self-compatible sunflower.

scholarly journals Self-Incompatibility Alleles in Iranian Pear Cultivars

2019 ◽  
Author(s):  
Maryam Bagheri ◽  
Ahmad Ershadi
Keyword(s):  
Rapid Method ◽  
Pcr Amplification ◽  
Self Incompatibility ◽  
Specific Primers ◽  
Specific Pcr ◽  
S Alleles ◽  
Allele Specific ◽  
Incompatibility Alleles ◽  
Consensus Primers ◽  
Allele Specific Pcr

AbstractIn the present study, the S-alleles of eighteen pear cultivars, (including fourteen cultivars planted commercially in Iran and four controls) are determined. 34 out of 36 S-alleles are detected using nine allele-specific primers, which are designed for amplification of S101/S102, S105, S106, S107, S108, S109, S111, S112 and S114, as well as consensus primers, PycomC1F and PycomC5R. S104, S101 and S105 were the most common S-alleles observed, respectively, in eight, seven and six cultivars. In 16 cultivars, (‘Bartlett’ (S101S102), ‘Beurre Giffard’ (S101S106), ‘Comice’ (S104S105), ‘Doshes’ (S104S107), ‘Koshia’ (S104S108), ‘Paskolmar’ (S101S105), ‘Felestini’ (S101S107), ‘Domkaj’ (S104S120), ‘Ghousi’ (S104S107), ‘Kaftar Bache’ (S104S120), ‘Konjoni’ (S104S108), ‘Laleh’ (S105S108), ‘Natanzi’ (S104S105), ‘Sebri’ (S101S104), ‘Se Fasleh’ (S101S105) and ‘Louise Bonne’ (S101S108)) both alleles are identified but in two cultivars, (‘Pighambari’ (S105) and ‘Shah Miveh Esfahan’ (S107)) only one allele is recognized. It is concluded that allele-specific PCR amplification can be considered as an efficient and rapid method to identify S-genotype of Iranian pear cultivars.

Sign in / Sign up

Export Citation Format

Share Document