Genetic evidence for the origin of diploid megagametophytes in Citrus

Esen, Asım; Soost, R. K.; Geraci, G.

doi:10.1093/oxfordjournals.jhered.a109188

Cited by 32 publications

(33 citation statements)

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“…ex Tan.). This hypothesis is consistent with the previous proposal of Esen et al [15], whereas Chen et al [9] proposed that unreduced egg cell was produced from the first meiotic division restitution (FDR) in sweet orange Embryo culture and germination rate All normal seeds with well formed type germinated and verified as diploid hybrids without any chromosome chimera by only one peak existed (Fig. 2).…”

Section: Ploidy Determinationsupporting

confidence: 91%

Frequency of Spontaneous Polyploids in Monoembryonic Jeju Native Citrus Species and Some Mandarin Cultivars

Chae¹,

Yun²,

Park³

et al. 2012

Journal of Life Science

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Polyploids are a potentially important germplasm source in seedless citrus breeding program. Seedlessness is one of the most promising traits of commercial mandarin breeds that mandarin triploid hybrids possess permanently. The formation of new constant triploid hybrids can be recovered through diploid species hybridization from the fusion of divalent gametes at low frequencyor intra-and inter-ploidy crosses. However, extensive breeding work based on small F1 hybrid seeds developed is impossible without a very effective aseptic methodology and ploidy event. In this study, in vitro embryo culture was employed to recover natural hybrids from monoembryonic diploid, open-pollinated mandarin. Flow cytometry was used to determine ploidy level. A total of 10,289 seeds were extracted from 792 fruits having approximately 13 seeds per fruit. Average frequency of small seeds developed was 7.1%, while the average frequency of small seeds per fruit were: 8.9% for 'Clementine' 10.2% for 'Harehime' 2.6% for 'Kamja' 3.1% for 'Pyunkyool' 2.8% for 'Sadookam' and 7.0% for 'Wilking' mandarin. Average size of a perfect seed was 49.52±0.07 mm 2 ('Clementine') while the small seed measured 7.95±0.04 mm 2 ('Clementine'), which was about 1/6 smaller than the perfect seed. In total, 731 small seeds were obtained and all of them contained only one embryo per seed. The efficiency of 'Clementine' was 14 times higher than 'Wilking' and more than 109 times higher than 'Pyunkyool'. The basic information on spontaneous polyploidy provides for the hybridization of constant triploids and increases the efficiency of conventional cross.

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Section: Ploidy Determinationsupporting

confidence: 91%

Frequency of Spontaneous Polyploids in Monoembryonic Jeju Native Citrus Species and Some Mandarin Cultivars

Chae¹,

Yun²,

Park³

et al. 2012

Journal of Life Science

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“…According to the genotype, the frequency of duplication in the female gametes can range from below 1% to over 20%. Esen et al, 1979 proposed that 2n eggs result from the abortion of the second meiotic division in the megaspore (SDR) in citrus. This hypothesis has been corroborated for Clementine (Citrus clementina Hort.…”

Section: Introductionmentioning

confidence: 99%

Multilocus half-tetrad analysis and centromere mapping in citrus: evidence of SDR mechanism for 2n megagametophyte production and partial chiasma interference in mandarin cv ‘Fortune’

et al. 2011

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The genetic structure of 2n gametes and, particularly, the parental heterozygosity restitution at each locus depends on the meiotic process by which they originated, with firstdivision restitution and second-division restitution (SDR) being the two major mechanisms. The origin of 2n gametes in citrus is still controversial, although sexual polyploidisation is widely used for triploid seedless cultivar development. In this study, we report the analysis of 2n gametes of mandarin cv 'Fortune' by genotyping 171 triploid hybrids with 35 simple sequence repeat markers. The microsatellite DNA allele counting-peak ratios method for alleledosage evaluation proved highly efficient in segregating triploid progenies and allowed half-tetrad analysis (HTA) by inferring the 2n gamete allelic configuration. All 2n gametes arose from the female genitor. The observed maternal heterozygosity restitution varied between 10 and 82%, depending on the locus, thus SDR appears to be the mechanism underlying 2n gamete production in mandarin cv 'Fortune'. A new method to locate the centromere, based on the best fit between observed heterozygosity restitution within a linkage group and theoretical functions under either partial or no chiasmata interference hypotheses was successfully applied to linkage group II. The maximum value of heterozygosity restitution and the pattern of restitution along this linkage group would suggest there is partial chiasma interference. The implications of such a restitution mechanism for citrus breeding are discussed.

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“…In the case of citrus, the seeds obtained from the triploid plants were produced with pollen from diploid species (Ollitrault et al, 2008). Wakana et al (1981) have shown that the formation of triploid embryos are associated with a pentaploid endosperm, which is a strong indication that triploid hybrids result from the fertilization of unreduced (2n) ovules by normal haploid (1n) pollen (Esen et al, 1979).…”

Section: Meiosis Of Triploidsmentioning

confidence: 99%

Evaluation of Interspecific-Interploid Hybrids (F1) and Back Crosses (BC1) in Hylocereus Species (Cactaceae)

Cisneros¹,

Tel-Zur²

2012

Meiosis - Molecular Mechanisms and Cytogenetic Diversity

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Genetic evidence for the origin of diploid megagametophytes in Citrus

Cited by 32 publications

References 0 publications

Frequency of Spontaneous Polyploids in Monoembryonic Jeju Native Citrus Species and Some Mandarin Cultivars

Frequency of Spontaneous Polyploids in Monoembryonic Jeju Native Citrus Species and Some Mandarin Cultivars

Multilocus half-tetrad analysis and centromere mapping in citrus: evidence of SDR mechanism for 2n megagametophyte production and partial chiasma interference in mandarin cv ‘Fortune’

Evaluation of Interspecific-Interploid Hybrids (F1) and Back Crosses (BC1) in Hylocereus Species (Cactaceae)

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