Self-incompatibility

Last updated

Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals (dioecy), and their various modes of spatial (herkogamy) and temporal (dichogamy) separation.

Contents

SI is best-studied and particularly common in flowering plants, [1] although it is present in other groups, including sea squirts and fungi. [2] In plants with SI, when a pollen grain produced in a plant reaches a stigma of the same plant or another plant with a matching allele or genotype, the process of pollen germination, pollen-tube growth, ovule fertilization, or embryo development is inhibited, and consequently no seeds are produced. SI is one of the most important means of preventing inbreeding and promoting the generation of new genotypes in plants and it is considered one of the causes of the spread and success of angiosperms on Earth.

Mechanisms of single-locus self-incompatibility

The best studied mechanisms of SI act by inhibiting the germination of pollen on stigmas, or the elongation of the pollen tube in the styles. These mechanisms are based on protein-protein interactions, and the best-understood mechanisms are controlled by a single locus termed S, which has many different alleles in the species population. Despite their similar morphological and genetic manifestations, these mechanisms have evolved independently, and are based on different cellular components; [3] therefore, each mechanism has its own, unique S-genes.

The S-locus contains two basic protein coding regions – one expressed in the pistil, and the other in the anther and/or pollen (referred to as the female and male determinants, respectively). Because of their physical proximity, these are genetically linked, and are inherited as a unit. The units are called S-haplotypes. The translation products of the two regions of the S-locus are two proteins which, by interacting with one another, lead to the arrest of pollen germination and/or pollen tube elongation, and thereby generate an SI response, preventing fertilization. However, when a female determinant interacts with a male determinant of a different haplotype, no SI is created, and fertilization ensues. This is a simplistic description of the general mechanism of SI, which is more complicated, and in some species the S-haplotype contains more than two protein coding regions. [ citation needed ]

Following is a detailed description of the different known mechanisms of SI in plants. [ citation needed ]

Gametophytic self-incompatibility (GSI)

In gametophytic self-incompatibility (GSI), the SI phenotype of the pollen is determined by its own gametophytic haploid genotype. This is the most common type of SI. [4] Two different mechanisms of GSI have been described in detail at the molecular level, and their description follows. [ citation needed ]

The RNase mechanism

In this mechanism, pollen tube elongation is halted when it has proceeded approximately one third of the way through the style. [5] The female component ribonuclease protein, termed S-RNase [6] probably causes degradation of the ribosomal RNA (rRNA) inside the pollen tube, in the case of identical male and female S alleles, and consequently pollen tube elongation is arrested, and the pollen grain dies. [5]

Within a decade of the initial confirmation their role in GSI, proteins belonging to the same RNase gene family were also found to cause pollen rejection in species of Rosaceae and Plantaginaceae. Despite initial uncertainty about the common ancestry of RNase-based SI in these distantly related plant families, phylogenetic studies [7] and the finding of shared male determinants (F-box proteins) [8] [9] [10] strongly supported homology across eudicots. Therefore, this mechanism likely arose approximately 90 million years ago, and is the inferred ancestral state for approximately 50% of all plant species. [7] [11]

In the past decade, the predictions about the wide distribution of this mechanism of SI have been confirmed, placing additional support of its single ancient origin. Specifically, a style-expressed T2/S-RNase gene and pollen-expressed F-box genes are now implicated in causing SI among the members of Rubiaceae, [12] Rutaceae, [13] and Cactaceae. [14] Therefore, other mechanisms of SI are thought to be recently derived in eudicots plants, in some cases relatively recently. One particularly interesting case is the Prunus SI systems, which functions through self-recognition [15] (the cytotoxic activity of the S-RNAses is inhibited by default and selectively activated by the pollen partner SFB upon self-pollination), [where "SFB" is a term that stands "for S-haplotype-specific F-box protein", as explained (parenthetically) in the abstract of [15] ], while SI in the other species with S-RNAse functions through non-self recognition (the S-RNAses are selectively detoxified upon cross-pollination).

The S-glycoprotein mechanism

In this mechanism, pollen growth is inhibited within minutes of its placement on the stigma. [5] The mechanism is described in detail for Papaver rhoeas and so far appears restricted to the plant family Papaveraceae. [ citation needed ]

The female determinant is a small, extracellular molecule, expressed in the stigma; the identity of the male determinant remains elusive, but it is probably some cell membrane receptor. [5] The interaction between male and female determinants transmits a cellular signal into the pollen tube, resulting in strong influx of calcium cations; this interferes with the intracellular concentration gradient of calcium ions which exists inside the pollen tube, essential for its elongation. [16] [17] [18] The influx of calcium ions arrests tube elongation within 1–2 minutes. At this stage, pollen inhibition is still reversible, and elongation can be resumed by applying certain manipulations, resulting in ovule fertilization. [5]

Subsequently, the cytosolic protein p26, a pyrophosphatase, is inhibited by phosphorylation, [19] possibly resulting in arrest of synthesis of molecular building blocks, required for tube elongation. There is depolymerization and reorganization of actin filaments, within the pollen cytoskeleton. [20] [21] Within 10 minutes from the placement on the stigma, the pollen is committed to a process which ends in its death. At 3–4 hours past pollination, fragmentation of pollen DNA begins, [22] and finally (at 10–14 hours), the cell dies apoptotically. [5] [23]

Sporophytic self-incompatibility (SSI)

In sporophytic self-incompatibility (SSI), the SI phenotype of the pollen is determined by the diploid genotype of the anther (the sporophyte) in which it was created. This form of SI was identified in the families: Brassicaceae, Asteraceae, Convolvulaceae, Betulaceae, Caryophyllaceae, Sterculiaceae and Polemoniaceae. [24] Up to this day, only one mechanism of SSI has been described in detail at the molecular level, in Brassica (Brassicaceae). [ citation needed ]

Since SSI is determined by a diploid genotype, the pollen and pistil each express the translation products of two different alleles, i.e. two male and two female determinants. Dominance relationships often exist between pairs of alleles, resulting in complicated patterns of compatibility/self-incompatibility. These dominance relationships also allow the generation of individuals homozygous for a recessive S allele. [25]

Compared to a population in which all S alleles are co-dominant, the presence of dominance relationships in the population, raises the chances of compatible mating between individuals. [25] The frequency ratio between recessive and dominant S alleles, reflects a dynamic balance between reproductive assurance (favoured by recessive alleles) and avoidance of selfing (favoured by dominant alleles). [26]

The SI mechanism in Brassica

As previously mentioned, the SI phenotype of the pollen is determined by the diploid genotype of the anther. In Brassica , the pollen coat, derived from the anther's tapetum tissue, carries the translation products of the two S alleles. These are small, cysteine-rich proteins. The male determinant is termed SCR or SP11, and is expressed in the anther tapetum as well as in the microspore and pollen (i.e. sporophytically). [27] [28] There are possibly up to 100 polymorphs of the S-haplotype in Brassica, and within these there is a dominance hierarchy. [ citation needed ]

The female determinant of the SI response in Brassica, is a transmembrane protein termed SRK, which has an intracellular kinase domain, and a variable extracellular domain. [29] [30] SRK is expressed in the stigma, and probably functions as a receptor for the SCR/SP11 protein in the pollen coat. Another stigmatic protein, termed SLG, is highly similar in sequence to the SRK protein, and seems to function as a co-receptor for the male determinant, amplifying the SI response. [31]

The interaction between the SRK and SCR/SP11 proteins results in autophosphorylation of the intracellular kinase domain of SRK, [32] [33] and a signal is transmitted into the papilla cell of the stigma. Another protein essential for the SI response is MLPK, a serine-threonine kinase, which is anchored to the plasma membrane from its intracellular side. [34] A downstream signaling cascade leads to proteasomal degradation that produces an SI response. [35]

Other mechanisms of self-incompatibility

These mechanisms have received only limited attention in scientific research. Therefore, they are still poorly understood.

2-locus gametophytic self-incompatibility

The grass subfamily Pooideae, and perhaps all of the family Poaceae, have a gametophytic self-incompatibility system that involves two unlinked loci referred to as S and Z. [36] If the alleles expressed at these two loci in the pollen grain both match the corresponding alleles in the pistil, the pollen grain will be recognized as incompatible. [36] At both loci, S and Z, two male and one female determinant can be found. All four male determinants encode proteins belonging to the same family (DUF247) and are predicted to be membrane-bound. The two female determinants are predicted to be secreted proteins with no protein family membership. [37] [38] [39]

Heteromorphic self-incompatibility

A distinct SI mechanism exists in heterostylous flowers, termed heteromorphic self-incompatibility. This mechanism is probably not evolutionarily related to the more familiar mechanisms, which are differentially defined as homomorphic self-incompatibility. [40]

Almost all heterostylous taxa feature SI to some extent. The loci responsible for SI in heterostylous flowers, are strongly linked to the loci responsible for flower polymorphism, and these traits are inherited together. Distyly is determined by a single locus, which has two alleles; tristyly is determined by two loci, each with two alleles. Heteromorphic SI is sporophytic, i.e. both alleles in the male plant, determine the SI response in the pollen. SI loci always contain only two alleles in the population, one of which is dominant over the other, in both pollen and pistil. Variance in SI alleles parallels the variance in flower morphs, thus pollen from one morph can fertilize only pistils from the other morph. In tristylous flowers, each flower contains two types of stamens; each stamen produces pollen capable of fertilizing only one flower morph, out of the three existing morphs. [40]

A population of a distylous plant contains only two SI genotypes: ss and Ss. Fertilization is possible only between genotypes; each genotype cannot fertilize itself. [40] This restriction maintains a 1:1 ratio between the two genotypes in the population; genotypes are usually randomly scattered in space. [41] [42] Tristylous plants contain, in addition to the S locus, the M locus, also with two alleles. [40] The number of possible genotypes is greater here, but a 1:1 ratio exists between individuals of each SI type. [43]

Cryptic self-incompatibility (CSI)

Cryptic self-incompatibility (CSI) exists in a limited number of taxa (for example, there is evidence for CSI in Silene vulgaris , Caryophyllaceae [44] ). In this mechanism, the simultaneous presence of cross and self pollen on the same stigma, results in higher seed set from cross pollen, relative to self pollen. [45] However, as opposed to 'complete' or 'absolute' SI, in CSI, self-pollination without the presence of competing cross pollen, results in successive fertilization and seed set; [45] in this way, reproduction is assured, even in the absence of cross-pollination. CSI acts, at least in some species, at the stage of pollen tube elongation, and leads to faster elongation of cross pollen tubes, relative to self pollen tubes. The cellular and molecular mechanisms of CSI have not been described. [ citation needed ]

The strength of a CSI response can be defined, as the ratio of crossed to selfed ovules, formed when equal amounts of cross and self pollen, are placed upon the stigma; in the taxa described up to this day, this ratio ranges between 3.2 and 11.5. [46]

Late-acting self-incompatibility (LSI)

Late-acting self-incompatibility (LSI) is also termed ovarian self-incompatibility (OSI). In this mechanism, self pollen germinates and reaches the ovules, but no fruit is set. [47] [48] LSI can be pre-zygotic (e.g. deterioration of the embryo sac prior to pollen tube entry, as in Narcissus triandrus [49] ) or post-zygotic (malformation of the zygote or embryo, as in certain species of Asclepias and in Spathodea campanulata [50] [51] [52] [53] ).

The existence of the LSI mechanism among different taxa and in general, is subject for scientific debate. Criticizers claim, that absence of fruit set is due to genetic defects (homozygosity for lethal recessive alleles), which are the direct result of self-fertilization (inbreeding depression). [54] [55] [56] Supporters, on the other hand, argue for the existence of several basic criteria, which differentiate certain cases of LSI from the inbreeding depression phenomenon. [47] [52]

Self-compatibility (SC)

Self-compatibility (SC) is the absence of genetic mechanisms which prevent self-fertilization resulting in plants that can reproduce successfully via both self-pollen and pollen from other individuals. Approximately one half of angiosperm species are SI, [1] the remainder being SC. Mutations that disable SI (resulting in SC) may become common or entirely dominate in natural populations. Pollinator decline, variability in pollinator service, the so-called "automatic advantage" of self-fertilisation, among other factors, may favor the loss of SI. [ citation needed ]

Many cultivated plants are SC, although there are notable exceptions, such as apples and Brassica oleracea. Human-mediated artificial selection through selective breeding is often responsible for SC among these agricultural crops. SC enables more efficient breeding techniques to be employed for crop improvement. However, when genetically similar SI cultivars are bred, inbreeding depression can cause a cross-incompatible form of SC to arise, such as in apricots and almonds. [57] [58] In this rare, intraspecific, cross-incompatible mechanism, individuals have more reproductive success when self-pollinated rather than when cross-pollinated with other individuals of the same species. In wild populations, intraspecific cross-incompatibility has been observed in Nothoscordum bivalve . [59]

See also

Related Research Articles

<span class="mw-page-title-main">Fertilisation</span> Union of gametes of opposite sexes during the process of sexual reproduction to form a zygote

Fertilisation or fertilization, also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or offspring. While processes such as insemination or pollination, which happen before the fusion of gametes, are also sometimes informally referred to as fertilisation, these are technically separate processes. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms, the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation.

<span class="mw-page-title-main">Pollen tube</span> Tubular structure to conduct male gametes of plants to the female gametes

A pollen tube is a tubular structure produced by the male gametophyte of seed plants when it germinates. Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells from the pollen grain—either from the stigma to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms. In maize, this single cell can grow longer than 12 inches (30 cm) to traverse the length of the pistil.

<span class="mw-page-title-main">Self-pollination</span> Form of

Self-pollination is a form of pollination in which pollen from one plant arrives at the stigma of a flower or at the ovule of the same plant. The term cross-pollination is used for the opposite case, where pollen from one plant moves to a different plant.

<span class="mw-page-title-main">Heterostyly</span> Two different types of flowers (style) on same plant

Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, termed "morphs", exist in the population. On each individual plant, all flowers share the same morph. The flower morphs differ in the lengths of the pistil and stamens, and these traits are not continuous. The morph phenotype is genetically linked to genes responsible for a unique system of self-incompatibility, termed heteromorphic self-incompatibility, that is, the pollen from a flower on one morph cannot fertilize another flower of the same morph.

Allogamy or cross-fertilization is the fertilization of an ovum from one individual with the spermatozoa of another. By contrast, autogamy is the term used for self-fertilization. In humans, the fertilization event is an instance of allogamy. Self-fertilization occurs in hermaphroditic organisms where the two gametes fused in fertilization come from the same individual. This is common in plants and certain protozoans.

The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.

Tristyly is a rare floral polymorphism that consists of three floral morphs that differ in regard to the length of the stamens and style within the flower. This type of floral mechanism is thought to encourage outcross pollen transfer and is usually associated with heteromorphic self-incompatibility to reduce inbreeding. It is an example of heterostyly and reciprocal herkogamy, like distyly, which is the more common form of heterostyly. Darwin first described tristylous species in 1877 in terms of the incompatibility of these three morphs.

<span class="mw-page-title-main">Nucellar embryony</span> Form of seed reproduction

Nucellar embryony is a form of seed reproduction that occurs in certain plant species, including many citrus varieties. Nucellar embryony is a type of apomixis, where eventually nucellar embryos from the nucellus tissue of the ovule are formed, independent of meiosis and sexual reproduction. During the development of seeds in plants that possess this genetic trait, the nucellus tissue which surrounds the megagametophyte can produce nucellar cells, also termed initial cells. These additional embryos (polyembryony) are genetically identical to the parent plant, rendering them as clones. By contrast, zygotic seedlings are sexually produced and inherit genetic material from both parents. Most angiosperms reproduce sexually through double fertilization. Different from nucellar embryony, double fertilization occurs via the syngamy of sperm and egg cells, producing a triploid endosperm and a diploid zygotic embryo. In nucellar embryony, embryos are formed asexually from the nucellus tissue. Zygotic and nucellar embryos can occur in the same seed (monoembryony), and a zygotic embryo can divide to produce multiple embryos. The nucellar embryonic initial cells form, divide, and expand. Once the zygotic embryo becomes dominant, the initial cells stop dividing and expanding. Following this stage, the zygotic embryo continues to develop and the initial cells continue to develop as well, forming nucellar embryos. The nucellar embryos generally end up outcompeting the zygotic embryo, rending the zygotic embryo dormant. The polyembryonic seed is then formed by the many adventitious embryos within the ovule. The nucellar embryos produced via apomixis inherit its mother's genetics, making them desirable for citrus propagation, research, and breeding.

<span class="mw-page-title-main">Gynodioecy</span> Coexistence of female and hermaphrodite within a population

Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate between hermaphroditism and dioecy.

<span class="mw-page-title-main">Corn silk</span> Shiny fibres at the tip of an ear of corn

Corn silk is a common name for Stigma maydis, the shiny, thread-like, weak fibers that grow as part of ears of corn (maize); the tuft or tassel of silky fibers that protrude from the tip of the ear of corn. The ear is enclosed in modified leaves called husks. Each individual fiber is an elongated style, attached to an individual ovary. The term probably originated sometime between 1850 and 1855.

Autogamy or self-fertilization refers to the fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a reproductive mechanism employed by many flowering plants. However, species of protists have also been observed using autogamy as a means of reproduction. Flowering plants engage in autogamy regularly, while the protists that engage in autogamy only do so in stressful environments.

<span class="mw-page-title-main">Monocotyledon reproduction</span> Flowering plant reproduction system

The monocots are one of the two major groups of flowering plants, the other being the dicots. In order to reproduce they utilize various strategies such as employing forms of asexual reproduction, restricting which individuals they are sexually compatible with, or influencing how they are pollinated. Nearly all reproductive strategies that evolved in the dicots have independently evolved in monocots as well. Despite these similarities and their close relatedness, monocots and dicots have distinct traits in their reproductive biologies.

Reproductive assurance occurs as plants have mechanisms to assure full seed set through selfing when outcross pollen is limiting. It is assumed that self-pollination is beneficial, in spite of potential fitness costs, when there is insufficient pollinator services or outcross pollen from other individuals to accomplish full seed set.. This phenomenon has been observed since the 19th century, when Darwin observed that self-pollination was common in some plants. Constant pollen limitation may cause the evolution of automatic selfing, also known as autogamy. This occurs in plants such as weeds, and is a form of reproductive assurance. As plants pursue reproductive assurance through self-fertilization, there is an increase in homozygosity, and inbreeding depression, due to genetic load, which results in reduced fitness of selfed offspring. Solely outcrossing plants may not be successful colonizers of new regions due to lack of other plants to outcross with, so colonizing species are expected to have mechanisms of reproductive assurance - an idea first proposed by Herbert G. Baker and referred to as Baker's "law" or "rule". Baker's law predicts that reproductive assurance affects establishment of plants in many contexts, including spread by weedy plants and following long-distance dispersal, such as occurs during island colonization. As plants evolve towards increase self-fertilization, energy is redirected to seed production rather than characteristics that increased outcrossing, such as floral attractants, which is a condition known as the selfing syndrome.

<span class="mw-page-title-main">Distyly</span>

Distyly is a type of heterostyly in which a plant demonstrates reciprocal herkogamy. This breeding system is characterized by two separate flower morphs, where individual plants produce flowers that either have long styles and short stamens, or that have short styles and long stamens. However, distyly can refer to any plant that shows some degree of self-incompatibility and has two morphs if at least one of the following characteristics is true; there is a difference in style length, filament length, pollen size or shape, or the surface of the stigma. Specifically these plants exhibit intra-morph self-incompatibility, flowers of the same style morph are incompatible. Distylous species that do not exhibit true self-incompatibility generally show a bias towards inter-morph crosses - meaning they exhibit higher success rates when reproducing with an individual of the opposite morph.

Late-acting self-incompatibility (LSI) is the occurrence of self-incompatibility (SI) in flowering plants where pollen tubes from self-pollen successfully reach the ovary, but ovules fail to develop. Mechanisms that might cause late-acting self-incompatibility have yet to be elucidated. One hypothesis is that the occurrence of LSI is caused by early-acting inbreeding depression where the expression of genetic load causes self-fertilized embryos to abort.

Cryptic self-incompatibility (CSI) is the botanical expression that's used to describe a weakened self-incompatibility (SI) system. CSI is one expression of a mixed mating system in flowering plants. Both SI and CSI are traits that increase the frequency of fertilization of ovules by outcross pollen, as opposed to self-pollen.

Gametophytic selection is the selection of one haploid pollen grain over another through the means of pollen competition, and that resulting sporophytic generations are positively affected by this competition. Evidence for the positive effects of gametophytic selection on the sporophyte generation has been observed in several flowering plant species, but there are is still some debate as to the biological significance of gametophytic selection.

June Nasrallah is Barbara McClintock Professor in the Plant Biology Section of the School of Integrative Plant Science at Cornell University. Her research focuses on plant reproductive biology and the cell-cell interactions that underlie self-incompatibility in plants belonging to the mustard (Brassicaceae) family. She was elected to the US National Academy of Sciences in 2003 for this work and her contributions generally to our understanding of receptor-based signaling in plants.

Vernonica "Noni" Elsa Franklin-Tong is an English plant cell biologist who is Emeritus Professor at the University of Birmingham. She is known for her studies on self-incompatibility in Papaver rhoeas. In 2021 she was elected a Fellow of the Royal Society.

Mikhail Elia Nasrallah is a plant scientist, specialising in the genetics of self-incompatibility in flowering plants. He is professor emeritus in the plant biology section of the School of Integrative Plant Science in the New York State College of Agriculture and Life Sciences at Cornell University.

References

  1. 1 2 Igic B, Lande R, Kohn JR (2008). "Loss of Self-Incompatibility and Its Evolutionary Consequences". International Journal of Plant Sciences. 169 (1): 93–104. doi:10.1086/523362. S2CID   15933118.
  2. Sawada H, Morita M, Iwano M (August 2014). "Self/non-self recognition mechanisms in sexual reproduction: new insight into the self-incompatibility system shared by flowering plants and hermaphroditic animals". Biochemical and Biophysical Research Communications. 450 (3): 1142–1148. doi:10.1016/j.bbrc.2014.05.099. PMID   24878524.
  3. Charlesworth D, Vekemans X, Castric V, Glémin S (October 2005). "Plant self-incompatibility systems: a molecular evolutionary perspective". The New Phytologist. 168 (1): 61–69. doi: 10.1111/j.1469-8137.2005.01443.x . PMID   16159321.
  4. Franklin FC, Lawrence MJ, Franklin-Tong VE (1995). "Cell and molecular biology of self-incompatibility in flowering plants". Int. Rev. Cytol. International Review of Cytology. 158: 1–64. doi:10.1016/S0074-7696(08)62485-7. ISBN   978-0-12-364561-6.
  5. 1 2 3 4 5 6 Franklin-Tong VE, Franklin FC (June 2003). "The different mechanisms of gametophytic self-incompatibility". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 358 (1434): 1025–1032. doi:10.1098/rstb.2003.1287. PMC   1693207 . PMID   12831468.
  6. McClure BA, Haring V, Ebert PR, Anderson MA, Simpson RJ, Sakiyama F, Clarke AE (1989). "Style self-incompatibility gene products of Nicotiana alata are ribonucleases". Nature. 342 (6252): 955–957. Bibcode:1989Natur.342..955M. doi:10.1038/342955a0. PMID   2594090. S2CID   4321558.
  7. 1 2 Igic B, Kohn JR (November 2001). "Evolutionary relationships among self-incompatibility RNases". Proceedings of the National Academy of Sciences of the United States of America. 98 (23): 13167–13171. doi: 10.1073/pnas.231386798 . PMC   60842 . PMID   11698683.
  8. Qiao H, Wang F, Zhao L, Zhou J, Lai Z, Zhang Y, et al. (September 2004). "The F-box protein AhSLF-S2 controls the pollen function of S-RNase-based self-incompatibility". The Plant Cell. 16 (9): 2307–2322. doi:10.1105/tpc.104.024919. PMC   520935 . PMID   15308757.
  9. Ushijima K, Yamane H, Watari A, Kakehi E, Ikeda K, Hauck NR, et al. (August 2004). "The S haplotype-specific F-box protein gene, SFB, is defective in self-compatible haplotypes of Prunus avium and P. mume". The Plant Journal. 39 (4): 573–586. doi: 10.1111/j.1365-313X.2004.02154.x . PMID   15272875.
  10. Sijacic P, Wang X, Skirpan AL, Wang Y, Dowd PE, McCubbin AG, et al. (May 2004). "Identification of the pollen determinant of S-RNase-mediated self-incompatibility". Nature. 429 (6989): 302–305. Bibcode:2004Natur.429..302S. doi:10.1038/nature02523. PMID   15152253. S2CID   4427123.
  11. Steinbachs JE, Holsinger KE (June 2002). "S-RNase-mediated gametophytic self-incompatibility is ancestral in eudicots". Molecular Biology and Evolution. 19 (6): 825–829. doi: 10.1093/oxfordjournals.molbev.a004139 . PMID   12032238.
  12. Asquini E, Gerdol M, Gasperini D, Igic B, Graziosi G, Pallavicini A (2011). "S-RNase-like Sequences in Styles of Coffea (Rubiaceae). Evidence for S-RNase Based Gametophytic Self-Incompatibility?". Tropical Plant Biology. 4 (3–4): 237–249. doi:10.1007/s12042-011-9085-2. S2CID   11092131.
  13. Liang M, Cao Z, Zhu A, Liu Y, Tao M, Yang H, et al. (February 2020). "Evolution of self-compatibility by a mutant Sm-RNase in citrus". Nature Plants. 6 (2): 131–142. doi:10.1038/s41477-020-0597-3. PMC   7030955 . PMID   32055045.
  14. Ramanauskas K, Igić B (September 2021). "RNase-based self-incompatibility in cacti". The New Phytologist. 231 (5): 2039–2049. doi: 10.1111/nph.17541 . PMID   34101188. S2CID   235370441.
  15. 1 2 Matsumoto D, Tao R (2016). "Distinct Self-recognition in the Prunus S-RNase-based Gametophytic Self-incompatibility System". The Horticulture Journal. 85 (4): 289–305. doi: 10.2503/hortj.MI-IR06 . ISSN   2189-0102. Archived from the original on 2022-09-28. Retrieved 2022-09-28.
  16. Franklin-Tong VE, Ride JP, Read ND, Trewavas AJ, Franklin FC (1993). "The self-incompatibility response in Papaver rhoeas is mediated by cytosolic free calcium". Plant J. 4: 163–177. doi: 10.1046/j.1365-313X.1993.04010163.x .
  17. Franklin-Tong VE, Hackett G, Hepler PK (1997). "Ratioimaging of Ca21 in the self-incompatibility response in pollen tubes of Papaver rhoeas". Plant J. 12 (6): 1375–86. doi: 10.1046/j.1365-313x.1997.12061375.x .
  18. Franklin-Tong VE, Holdaway-Clarke TL, Straatman KR, Kunkel JG, Hepler PK (February 2002). "Involvement of extracellular calcium influx in the self-incompatibility response of Papaver rhoeas". The Plant Journal. 29 (3): 333–345. doi: 10.1046/j.1365-313X.2002.01219.x . PMID   11844110. S2CID   954229.
  19. Rudd JJ, Franklin F, Lord JM, Franklin-Tong VE (April 1996). "Increased Phosphorylation of a 26-kD Pollen Protein Is Induced by the Self-Incompatibility Response in Papaver rhoeas". The Plant Cell. 8 (4): 713–724. doi:10.1105/tpc.8.4.713. PMC   161131 . PMID   12239397.
  20. Geitmann A, Snowman BN, Emons AM, Franklin-Tong VE (July 2000). "Alterations in the actin cytoskeleton of pollen tubes are induced by the self-incompatibility reaction in Papaver rhoeas". The Plant Cell. 12 (7): 1239–1251. doi:10.1105/tpc.12.7.1239. PMC   149062 . PMID   10899987.
  21. Snowman BN, Kovar DR, Shevchenko G, Franklin-Tong VE, Staiger CJ (October 2002). "Signal-mediated depolymerization of actin in pollen during the self-incompatibility response". The Plant Cell. 14 (10): 2613–2626. doi:10.1105/tpc.002998. PMC   151239 . PMID   12368508.
  22. Jordan ND, Franklin FC, Franklin-Tong VE (August 2000). "Evidence for DNA fragmentation triggered in the self-incompatibility response in pollen of Papaver rhoeas". The Plant Journal. 23 (4): 471–479. doi: 10.1046/j.1365-313x.2000.00811.x . PMID   10972873.
  23. Thomas SG, Franklin-Tong VE (May 2004). "Self-incompatibility triggers programmed cell death in Papaver pollen". Nature. 429 (6989): 305–309. Bibcode:2004Natur.429..305T. doi:10.1038/nature02540. PMID   15152254. S2CID   4376774.
  24. Goodwillie C (1997). "The genetic control of self-incompatibility in Linanthus parviflorus (Polemoniaceae)". Heredity. 79 (4): 424–432. doi: 10.1038/hdy.1997.177 .
  25. 1 2 Hiscock SJ, Tabah DA (June 2003). "The different mechanisms of sporophytic self-incompatibility". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 358 (1434): 1037–1045. doi:10.1098/rstb.2003.1297. PMC   1693206 . PMID   12831470.
  26. Ockendon DJ (1974). "Distribution of self-incompatibility alleles and breeding structure of open-pollinated cultivars of Brussels sprouts". Heredity. 32 (2): 159–171. doi: 10.1038/hdy.1974.84 .
  27. Schopfer CR, Nasrallah ME, Nasrallah JB (November 1999). "The male determinant of self-incompatibility in Brassica". Science. 286 (5445): 1697–1700. doi:10.1126/science.286.5445.1697. PMID   10576728.
  28. Takayama S, Shiba H, Iwano M, Shimosato H, Che FS, Kai N, et al. (February 2000). "The pollen determinant of self-incompatibility in Brassica campestris". Proceedings of the National Academy of Sciences of the United States of America. 97 (4): 1920–1925. Bibcode:2000PNAS...97.1920T. doi: 10.1073/pnas.040556397 . PMC   26537 . PMID   10677556.
  29. Stein JC, Howlett B, Boyes DC, Nasrallah ME, Nasrallah JB (October 1991). "Molecular cloning of a putative receptor protein kinase gene encoded at the self-incompatibility locus of Brassica oleracea". Proceedings of the National Academy of Sciences of the United States of America. 88 (19): 8816–8820. Bibcode:1991PNAS...88.8816S. doi: 10.1073/pnas.88.19.8816 . PMC   52601 . PMID   1681543.: .
  30. Nasrallah JB, Nasrallah ME (1993). "Pollen–stigma signalling in the sporophytic self-incompatibility response". Plant Cell. 5 (10): 1325–35. doi:10.2307/3869785. JSTOR   3869785.
  31. Takasaki T, Hatakeyama K, Suzuki G, Watanabe M, Isogai A, Hinata K (February 2000). "The S receptor kinase determines self-incompatibility in Brassica stigma". Nature. 403 (6772): 913–916. Bibcode:2000Natur.403..913T. doi:10.1038/35002628. PMID   10706292. S2CID   4361474.
  32. Schopfer CR, Nasrallah JB (November 2000). "Self-incompatibility. Prospects for a novel putative peptide-signaling molecule". Plant Physiology. 124 (3): 935–940. doi:10.1104/pp.124.3.935. PMC   1539289 . PMID   11080271.
  33. Takayama S, Shimosato H, Shiba H, Funato M, Che FS, Watanabe M, et al. (October 2001). "Direct ligand-receptor complex interaction controls Brassica self-incompatibility". Nature. 413 (6855): 534–538. Bibcode:2001Natur.413..534T. doi:10.1038/35097104. PMID   11586363. S2CID   4419954.
  34. Murase K, Shiba H, Iwano M, Che FS, Watanabe M, Isogai A, Takayama S (March 2004). "A membrane-anchored protein kinase involved in Brassica self-incompatibility signaling". Science. 303 (5663): 1516–1519. Bibcode:2004Sci...303.1516M. doi:10.1126/science.1093586. PMID   15001779. S2CID   29677122.
  35. Subramanian Sankaranarayanan, Muhammad Jamshed, and Marcus A. Samuel, "Degradation of glyoxalase I in Brassica napus stigma leads to self-incompatibility response", Nature Plants, 1 (12), doi:10.1038/nplants.2015.185 {{citation}}: CS1 maint: multiple names: authors list (link)
  36. 1 2 Baumann U, Juttner J, Bian X, Langridge P (2000). "Self-incompatibility in the Grasses". Annals of Botany. 85 (Supplement A): 203–209. doi: 10.1006/anbo.1999.1056 .
  37. Rohner M, Manzanares C, Yates S, Thorogood D, Copetti D, Lübberstedt T, et al. (January 2023). "Fine-Mapping and Comparative Genomic Analysis Reveal the Gene Composition at the S and Z Self-incompatibility Loci in Grasses". Molecular Biology and Evolution. 40 (1). doi:10.1093/molbev/msac259. PMC   9825253 . PMID   36477354.
  38. Lian X, Zhang S, Huang G, Huang L, Zhang J, Hu F (2021). "Confirmation of a Gametophytic Self-Incompatibility in Oryza longistaminata". Frontiers in Plant Science. 12: 576340. doi: 10.3389/fpls.2021.576340 . PMC   8044821 . PMID   33868321.
  39. Shinozuka H, Cogan NO, Smith KF, Spangenberg GC, Forster JW (February 2010). "Fine-scale comparative genetic and physical mapping supports map-based cloning strategies for the self-incompatibility loci of perennial ryegrass (Lolium perenne L.)". Plant Molecular Biology. 72 (3): 343–355. doi:10.1007/s11103-009-9574-y. PMID   19943086. S2CID   25404140.
  40. 1 2 3 4 Ganders FR (1979). "The biology of heterostyly". New Zealand Journal of Botany. 17 (4): 607–635. doi: 10.1080/0028825x.1979.10432574 .
  41. Ornduff R, Weller SG (June 1975). "Pattern diversity of incompatibility groups in Jepsonia heterandra (Saxifragaceae) (SAXIFRAGACEAE)". Evolution; International Journal of Organic Evolution. 29 (2): 373–375. doi:10.2307/2407228. JSTOR   2407228. PMID   28555865.
  42. Ganders FR (1976). "Pollen flow in distylous populations of Amsinckia (Boraginaceae)". Canadian Journal of Botany. 54 (22): 2530–5. doi:10.1139/b76-271.
  43. Spieth PT (December 1971). "A necessary condition for equilibrium in systems exhibiting self-incompatible mating". Theoretical Population Biology. 2 (4): 404–418. doi:10.1016/0040-5809(71)90029-3. PMID   5170719.
  44. Glaettli, M. (2004). Mechanisms involved in the maintenance of inbreeding depression in gynodioecious Silene vulgaris (Caryophyllaceae): an experimental investigation. PhD dissertation, University of Lausanne.
  45. 1 2 Bateman AJ (1956). "Cryptic self-incompatibility in the wallflower: Cheiranthus cheiri L". Heredity. 10 (2): 257–261. doi: 10.1038/hdy.1956.22 .
  46. Travers SE, Mazer SJ (February 2000). "The absence of cryptic self-incompatibility in Clarkia unguiculata (Onagraceae)". American Journal of Botany. 87 (2): 191–196. doi:10.2307/2656905. JSTOR   2656905. PMID   10675305.
  47. 1 2 Seavey SF, Bawa KS (1986). "Late-acting self-incompatibility in angiosperms". Botanical Review. 52 (2): 195–218. doi:10.1007/BF02861001. S2CID   34443387.
  48. Sage TL, Bertin RI, Williams EG (1994). "Ovarian and other late-acting self-incompatibility systems". In Williams EG, Knox RB, Clarke AE (eds.). Genetic control of self-incompatibility and reproductive development in flowering plants. Advances in Cellular and Molecular Biology of Plants. Vol. 2. Amsterdam: Kluwer Academic. pp. 116–140. doi:10.1007/978-94-017-1669-7_7. ISBN   978-90-481-4340-5.
  49. Sage TL, Strumas F, Cole WW, Barrett SC (June 1999). "Differential ovule development following self- and cross-pollination: the basis of self-sterility in Narcissus triandrus (Amaryllidaceae)". American Journal of Botany. 86 (6): 855–870. doi: 10.2307/2656706 . JSTOR   2656706. PMID   10371727. S2CID   25585101.
  50. Sage TL, Williams EG (1991). "Self-incompatibility in Asclepias". Plant Cell Incomp. Newsl. 23: 55–57.
  51. Sparrow FK, Pearson NL (1948). "Pollen compatibility in Asclepias syriaca". J. Agric. Res. 77: 187–199.
  52. 1 2 Lipow SR, Wyatt R (February 2000). "Single gene control of postzygotic self-incompatibility in poke milkweed, Asclepias exaltata L". Genetics. 154 (2): 893–907. doi:10.1093/genetics/154.2.893. PMC   1460952 . PMID   10655239.
  53. Bittencourt NS, Gibbs PE, Semir J (June 2003). "Histological study of post-pollination events in Spathodea campanulata beauv. (Bignoniaceae), a species with late-acting self-incompatibility". Annals of Botany. 91 (7): 827–834. doi:10.1093/aob/mcg088. PMC   4242391 . PMID   12730069.
  54. Klekowski EJ (1988). Mutation, Developmental Selection, and Plant Evolution. New York: Columbia University Press.
  55. Waser NM, Price MV (1991). "Reproductive costs of self-pollination in Ipomopsis aggregata (Polemoniaceae): are ovules usurped?". American Journal of Botany. 78 (8): 1036–43. doi:10.2307/2444892. JSTOR   2444892.
  56. Lughadha N (1998). "Preferential outcrossing in Gomidesia (Myrtaceae) is maintained by a post-zygotic mechanism.". In Owen SJ, Rudall PJ (eds.). Reproductive biology in systematics, conservation and economic botany. London: Royal Botanic Gardens, Kew. pp. 363–379. doi:10.13140/RG.2.1.2787.0247.
  57. Egea J, Burgos L (November 1996). "Detecting cross-incompatibility of three North American apricot cultivars and establishing the first incompatibility group in apricot". Journal of the American Society for Horticultural Science. 121 (6): 1002–1005. doi: 10.21273/JASHS.121.6.1002 . Retrieved 25 December 2020.
  58. Gómez EM, Dicenta F, Batlle I, Romero A, Ortega E (19 February 2019). "Cross-incompatibility in the cultivated almond (Prunus dulcis): Updating, revision and correction". Scientia Horticulturae. 245: 218–223. doi:10.1016/j.scienta.2018.09.054. hdl: 20.500.12327/55 . S2CID   92428859. Archived from the original on 19 March 2022. Retrieved 25 December 2020.
  59. Weiherer DS, Eckardt K, Bernhardt P (July 2020). "Comparative floral ecology and breeding systems between sympatric populations of Nothoscordum bivalve and Allium stellatum (Amaryllidaceae)". Journal of Pollination Ecology. 26 (3): 16–31. doi: 10.26786/1920-7603(2020)585 . S2CID   225237548. Archived from the original on 29 July 2024. Retrieved 25 December 2020.

Further reading