Unexpected Triploids in Citrus: Their Origin, Identification, and Possible Use

Esen, Asım; Soost, R. K.

doi:10.1093/oxfordjournals.jhered.a108186

Cited by 102 publications

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“…This confirms that all triploid hybrids found in the progenies of 2x Â 2x crosses with 'Fortune' mandarin as female genitor arose from 2n megaspores. This result is in agreement with the cytogenetic observations of Esen and Soost (1971), and with previous molecular observations (Luro et al, 2000;Chen et al, 2008;Ferrante et al, 2010). In the present work, the restitution heterozygosity rates significantly lower than 50% for several markers (distributed in six of the eight represented linkage groups) and the pattern of heterozygosity inside linkage group II, definitively ruled out the FDR hypothesis.…”

Section: Origin Of 2n Gamete-producing Triploids In Citrussupporting

confidence: 94%

“…The recovery of triploid citrus hybrids arising from 2n megagametophytes produced by diploid plants was described in the 1970s Soost, 1971, 1973). Cytogenetic studies (Esen and Soost, 1971) showed that triploid embryos are associated with pentaploid endosperm, indicating that triploid hybrids result from the fertilisation of unreduced ovules by normal haploid pollen. According to the genotype, the frequency of duplication in the female gametes can range from below 1% to over 20%.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Origin Of 2n Gamete-producing Triploids In Citrussupporting

confidence: 94%

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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“…Lee (1988) descreveu diversas formas de obtenção de plantas cítricas triplóides (3x = 27). Entre elas, a obtenção de híbridos sexuais triplóides foi relatada a partir de cruzamentos de cultivares diplóides (2x) com tetraplóides (4x) (Esen & Soost, 1972;Esen et al, 1978) ou de diplóides (2x) com diplóides (2x) (Esen & Soost, 1971). Neste último cruzamento, os embriões triplóides originaram-se da fertilização de gametas femininos não-reduzidos (diplóides), com gametas masculinos reduzidos (haplóides).…”

Section: Introductionunclassified

Plantas autotetraplóides de citros sob tratamento in vitro com colchicina

Latado

Cristofani–Yaly

Carvalho

et al. 2007

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi obter plantas autotetraplóides de tangerina 'Ponkan', laranja 'Pêra-de-abril' e tangor 'Murcott', que serão usadas em cruzamentos com cultivares diplóides, visando à obtenção de indivíduos triplóides sem sementes. Utilizou-se o método de cultivo in vitro de segmentos de epicótilo em meio com colchicina (0,025, 0,05 e 0,1%), por diversos períodos (1, 2, 3, 7 e 14 dias), com subseqüente regeneração de brotações em meio sem a presença do alcalóide. As brotações foram microenxertadas in vitro e aclimatizadas em estufas. A determinação do nível de ploidia das plantas foi realizada por citometria de fluxo. A colchicina demonstrou ser tóxica aos explantes das três variedades, ocasionando redução significativa no número médio de brotações adventícias e aumento na porcentagem de explantes não-responsivos, em comparação com o controle. Entre as quatro plantas de laranja e uma de tangor obtidas, duas plantas de laranja e a de tangor, demonstraram ser autotetraplóides, apresentando folhas com maior espessura, arredondadas e coloração verde intensa. O método utilizado na duplicação cromossômica, com uso de colchicina, é eficiente em produzir plantas autotetraplóides de citros.Termos para indexação: Citrus, tetraplóide, epicótilo, regeneração in vitro, cultura de tecidos. Citrus autotetraploid plants obtained by in vitro treatment with colchicineAbstract -The objective of this work was to obtain autotetraploid plants of 'Murcott' tangor, 'Ponkan' mandarin and 'Pêra-de-abril' sweet orange to be used in crosses with diploid cultivars, aiming to produce triploid seedless hybrids. The methodology used was the in vitro culture of epicotyl segments in media containing different concentrations of colchicine (0.025, 0.05 and 0.1%), for several periods of time (1, 2, 3, 7 and 14 days), followed by the regeneration of adventitious shoots in culture media without the alkaloid. All shoots obtained were micrografted, acclimatized and transferred to a greenhouse. The evaluation of the ploidy level of the plants was performed by flow citometry technique. Colchicine was toxic to the explants of three varieties, and caused the reduction on the average number of shoots regenerated per explant as well as an increase in the percentage of non-responsive explants when comparing with the control plants. Among four plants of sweet orange obtained, two of them showed to be autotetraploid. The only plant of tangor obtained also showed to be autotetraploid. These plants presented thicker and roundisher leaves displaying deeper green color. The methodology used resulted efficient for obtaining tetraploid plants.

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“…Other polyploid progenies have often been emerged by ploidy event and interploid cross. Few triploids [1,12,14,19,32], tetraploids [4,6,33] and aneuploids [31] described and developed by spontaneous and artificial breeding approaches.…”

Section: Introductionmentioning

confidence: 99%

“…Most of them are found in small and abnormal seeds [1,2,12,14,19]. The small seeds produced are due to the endosperm's failure to develop normally [10] and the high probability of seed germination failure under greenhouse condition.…”

Section: Introductionmentioning

confidence: 99%

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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Unexpected Triploids in Citrus: Their Origin, Identification, and Possible Use

Cited by 102 publications

References 0 publications

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’

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’

Plantas autotetraplóides de citros sob tratamento in vitro com colchicina

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

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