Self-incompatibility in Acacia retinodes: Site of pollen-tube arrest is the nucellus

Kenrick, J.; Kaul, V.; Williams, Elizabeth

doi:10.1007/bf00392321

Cited by 83 publications

(46 citation statements)

References 24 publications

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“…Otherwise, another mechanism is acting in early embryos leading to seed abortion (Westoby and Rice 1982). While it is conceptually straightforward to distinguish between these phenomena (SI and early inbreeding depression), in practise it can be difficult, especially in cases where rejection of self pollen occurs in the ovary (late-acting or ovarian self-incompatibility) (Kenrick et al 1986;Gibbs and Bianchi 1993;Seavey and Bawa 1986;Sage et al 1994). Inbreeding depression is a frequent event in flowering plants and often acts between fertilisation and seed maturation to decrease seed-set (Hamilton and MitchelOlds 1994;Husband and Schemske 1996).…”

Section: Discussionmentioning

confidence: 99%

Sexual reproduction in the cork oak ( Quercus suber L). II. Crossing intra- and interspecific barriers

Boavida¹,

Silva²,

Feijó³

2001

Sexual Plant Reproduction

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Intraspecific barriers promote outcrossing while interspecific mechanisms may contribute to the isolation of species; both control the exchange of genes between plants. In this paper we establish that post-pollination mechanisms promote outcross and act at different temporal and spatial levels to control seed set and quality in Quercus species. Controlled pollinations were performed to investigate intraspecific crossing barriers in Q. suber and pollen-pistil interactions following interspecific pollinations with some simpatric Quercus species. Cytological data of intraspecific crosses in Q. suber and Q. ilex have shown different kinetics on pollen tube growth after self and outcross pollination, but pollen tubes were able to reach the base of the styles in both species and seed set was successful. Although some prezygotic interaction is occurring at the style, the most important interaction takes place at ovary. The cross between Q. ilex and Q. suber is possible only in one direction, revealing a case of unilateral incongruity. We show that the lack of seed set observed in the cross Q. suber × Q. ilex is due to the inability of pollen tubes to penetrate the transmitting tissue after germination. With Q. suber mainly as female parent, pollinations with other simpatric Quercus species have shown different levels of constraint on pollen tube progression at stigma and style levels. Eventual hybridisation between Quercus species will depend on the compatibility of pollen-pistil interactions, on the competitive ability of pollen genotypes, and, most important, on the overlapping of geographical, phenological and ecological factors. Differences in seed set and seed allocation was evident in all crosses, and was particularly outstanding in interspecific and in self intraspecific crosses, determining the ultimate level of seed production and quality in Quercus species.

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Section: Discussionmentioning

confidence: 99%

Sexual reproduction in the cork oak ( Quercus suber L). II. Crossing intra- and interspecific barriers

Boavida¹,

Silva²,

Feijó³

2001

Sexual Plant Reproduction

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“…Typically, incompatibility reactions occur at the stigmatic surface or in the style. Failure of pollen tubes in the ovules has been reported for some species (Kenrick et al, 1986;Scribailo & Barrett, 1991;Broyles & Wyatt, 1993) incompatibility (Seavey & Bawa, 1986). In contrast, inbreeding depression is a process acting in the zygote as a function of the zygote's genotype.…”

Section: Discussionmentioning

confidence: 99%

Magnitude and timing of inbreeding depression in a diploid population of Epilobium angustifolium (Onagraceae)

1995

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Evolutionary theory predicts a negative correlation between the rate of self-fertilization and the magnitude of inbreeding depression in natural plant populations. We examined the mating system and inbreeding depression at four life stages in a diploid population of Epilobium angustifolium (Onagraceae). The multilocus rate of self-fertilization, inferred from the segregation of allozymes at two polymorphic loci (Pgi-2, Mdh-2) among seedlings from 22 open-pollinated plants, was 0.06 (SE± 0.10). However, after adjusting for differential mortality of selfed progeny prior to the seedling stage, the selfing rate was 0.45. The parental inbreeding coefficient (F) was -0.26 (SE 0.103) indicating more heterozygotes than in a randomly mating population. The magnitude of inbreeding depression at seed maturation, seed germination, juvenile survival and dry mass at 8 weeks was measured in a greenhouse experiment. Thirty-four plants, grown from open-pollinated seed, were each self-fertilized and randomly outcrossed. We observed significant inbreeding depression at all four stages, although its magnitude differed significantly among maternal plants and among stages. Inbreeding depression was largest during seed maturation (0.87), where seed-set in outcrossed flowers (65.7 per cent) was eight times higher than in selfed flowers (8.3 per cent). Inbreeding depression for dry mass after 8 weeks (0.50) was at least twice that for germination (0.25) and survival (0.15). The magnitude of inbreeding depression for each of the 34 maternal parents was not significantly correlated across life stages, suggesting that its genetic basis varies across the life cycle. Our results indicate that E. angustifolium exhibits high levels of inbreeding depression, much of which is expressed early in the life cycle, during seed maturation, consistent with results for other long-lived, outcrossing species. However, given its moderate rate of self-fertilization, the total inbreeding depression (0.95) maintained in E. angustifolium is very high in comparison to other angiosperms.

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“…Por outro lado, existe uma evidência para rejeição prezigótica em Acacia retinodes Schltdl. (Kenrick et al 1986).…”

Section: Discussionunclassified

Sistema reprodutivo e polinização de Senna multijuga (Fabaceae) em Mata Atlântica Montana

Wolowski

Freitas

2010

Rodriguésia

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ResumoO conhecimento da biologia reprodutiva e polinização de árvores neotropicais vêm aumentando nas últimas décadas. No entanto, ainda é incipiente para a Mata Atlântica e muitas questões persistem, por exemplo, sobre a prevalência de autoincompatibilidade. A biologia floral, o sistema reprodutivo e os visitantes florais de Senna multijuga foram estudados, com o objetivo de verificar a ocorrência de autoincompatibilidade e determinar seus polinizadores. A espécie apresenta características florais típicas do gênero, como flores assimétricas, enantiostilia, heteranteria e deiscência poricida. A antese é diurna e a viabilidade do pólen não diferiu entre os morfos de anteras. Os polinizadores foram abelhas dos gêneros Bombus, Epicharis, Centris e Xylocopa e abelhas menores atuaram como pilhadores de pólen. A reprodução sexual em S. multijuga depende da transferência de pólen pelos polinizadores, pois não foram formados frutos por apomixia ou autopolinização. Este último resultado pode ser devido à depressão por endogamia ou a um mecanismo de autoincompatibilidade de ação tardia, uma vez que houve aborto uniforme de pistilos e penetração de tubos polínicos nos óvulos após autopolinização. Diferença na fecundidade após polinização manual e em condições naturais indica que a limitação polínica afeta o sucesso reprodutivo feminino, assim como a disponibilidade de recursos. Palavras-chave: autoincompatibilidade de ação tardia, depressão por endogamia, flor de pólen, polinização. AbstractKnowledge of reproductive biology and pollination of Neotropical tree species has been increasing in recent decades. However, this is still incipient in the Atlantic Forest, and many questions remain, for instance, about the prevalence of self-incompatibility. We studied the floral biology, breeding system and floral visitors of Senna multijuga in order to verify the occurrence of self-incompatibility and determine its pollinators. This species bears the typical floral traits of the genus, such as asymmetry, enantiostily, heteranthery and poricid anthers. Anthesis is diurnal and pollen viability did not differ among the morphs of anthers. Pollinators were bees of the genera Bombus, Epicharis, Centris and Xylocopa and smaller bees acted as pollen thieves. Sexual reproduction of Senna multijuga depends on the transfer of pollen by pollinators, as no fruit was formed by either apomixis or self-pollination. The latter result may be due to inbreeding depression or by a mechanism of late-acting selfincompatibility, as we observed after self-pollination both penetration of pollen tubes in the ovules and uniform abortion of pistils. Differences on fertility after manual crossings and under natural conditions indicate that female fitness is affected by pollen limitation, as well as by the availability of resources.

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Self-incompatibility in Acacia retinodes: Site of pollen-tube arrest is the nucellus

Cited by 83 publications

References 24 publications

Sexual reproduction in the cork oak ( Quercus suber L). II. Crossing intra- and interspecific barriers

Sexual reproduction in the cork oak ( Quercus suber L). II. Crossing intra- and interspecific barriers

Magnitude and timing of inbreeding depression in a diploid population of Epilobium angustifolium (Onagraceae)

Sistema reprodutivo e polinização de Senna multijuga (Fabaceae) em Mata Atlântica Montana

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