Abstract
Citrus breeding programs normally face several biological obstacles such as apomixis and polyembryony that result in a cumbersome identification of hybrid seedlings. The main purpose of this work is to describe the combined use of visual selection based on the leaf apex morphology and SSR analysis to differentiate hybrid from nucellar seedlings derived from the cross between the ‘Murcott’ tangor [Citrus reticulata Blanco × Citrus sinensis (L.) Osb.] and ‘Pêra’ sweet orange [Citrus sinensis(L.) Osb.]. A new morphological variable named leaf apex morphometric index is also described as the quantitative basis of the visual selection. The efficiency of visual selection of hybrids was tested under two growth conditions, seedlings germinated in seedbeds and in plastic tubes. Putative hybrid seedlings were also confirmed through the analysis of simple sequence repeats (SSR). The visual selection of hybrid seedlings resulted in an increase of 87.2% (p < 0.01) and 202.2% (p <0.001) in the number of correctly identified hybrids when compared to the method of random picking of seedlings in seedbeds and plastic tubes,respectively. The results indicate that the combination of visual selection and SSR analysis for the identification of hybrids derived from the cross of polyembryonic citrus cultivars will improve the accuracy of the selection,save time, and reduce the costs involved in the use of molecular markers alone in citrus breeding programs.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Anderson, C.M., W.S. Castle & G.A. Moore, 1991. Isozymic identification of zygotic seedlings in Swingle citrumelo Citrus paradisi × Poncirus trifoliata nursery and field populations. J Amer Soc Hort Sci 116: 322–326.
Ballvé, R.M.L., H.P Medina Filho & R. Bordignon, 1997. Identification of reciprocal hybrids in citrus by the broadness of the leaf petiole wing. Braz J Genet 20: 697–702.
Bastianel, M., S.F. Schwarz, H.D. Colleta Filho, L.L. Lin, M.A. Machado & O.C Koller, 1998. Identification of zygotic and nucellar tangerine seedlings (Citrus spp.) using RAPD. Genet Mol Biol 21: 123–127.
Bercovich, D., Z. Regev, T. Ratz, A. Luder, Y. Plutsky, and Y. Gruenbaum. 1999. Quantitative ratio of primer pair and annealing temperature affecting PCR products in duplex amplification. Biotechniques 27: 762–770.
Cameron, J.W & H.B. Frost, 1968. Genetics, Breeding, and Nucellar Embryony. In: W. Reuther, L.D. Batchelor & H.J. Webber (Eds.), The Citrus Industry II, pp. 325–370. California Univ. Press, Berkeley.
Cooper, W.C., P.C. Reece & J.R. Furr, 1962. Citrus breeding in Florida: past, present and future. Proc Florida State Hort Soc 75: 5–13.
Cristofani, M., R.V. Brondani, V.M. Novelli & M.A. Machado, 1998. Desenvolvimento de marcadores microsatélites para análise genética em citros. Genet Mol Biol 21: 222.
Domingues, E.T., 1998. Caracterizaç ã o morfoló gica, agronô mica, isoenzimática e por RAPD de variedades de laranja doce - Citrus sinensis (L.) Osbeck. PhD thesis. ESALQ, Piracicaba, 246 p.
Donadio, L.C., 1979. Estudo de alguns caracteres morfoló gicos de progê nies obtidas de hibridaç õ es de cultivares poliembriô nicas de Citrus. Tese de Livre Docê ncia. UNESP, Jaboticabal, 76 p.
Frost, H.B. & R.K. Soost, 1968. Seed Reproduction: Development of Gametes and Embryos. In: W. Reuther, L.D. Batchelor & H.J. Webber (Eds.), The Citrus Industry II, pp. 290–324. California Univ. Press, Berkeley.
Furr, J.R. & P.C. Reece, 1946. Identification of hybrid and nucellar citrus seedlings by a modification of the rootstock color test. Proc Amer Soc Hort Sci 48: 141–146.
Hearn, C.J., 1977. Recognition of zygotic seedlings in certain orange crosses by vegetative characters. Proc Int Soc Citric 2: 611–614.
Kijas, J.M.H., F.C.S. Fowler & M.R. Thomas, 1995. An evaluation of sequence tagged microsatellite site markers for genetic analysis within Citrus and related species. Genome 38: 349–355.
Lima, H., 1977. Evaluation of the effectiveness to two techniques used to separate nucellar and zygotic Citrus seedlings. Int Soc Citric, p. 80.
Lima, J.E.O., 1988. Novas técnicas de produç ã o de mudas cítricas. Laranja 7: 463–468.
Machado, M.A., H.D. Colleta Filho, M.L.P.N. Targon & J. Pompeu Junior, 1996. Genetic relationship of Mediterranean mandarins (Citrus deliciosa Tenore) using RAPD markers. Euphytica 92: 321–326.
Moore, G.A. & W.S. Castle, 1988. Morphological and isozymic analysis of open-pollinated Citrus rootstock populations. Heredity 79: 59–63.
Murray, M.G. & W.F. Thompson, 1980. Rapid isolation of high molecular weight plant DNA. Nucl Acids Res 8: 4321–4325.
Pieringer, A.P. & G.J. Edwards, 1967. Identification of nucelar and zygotic citrus seedlings by infrared spectroscopy. Proc Am Soc Hort Sci 86: 226–234.
Ribeiro, V.G., M. Pasqual, J.D. Ramos, E. Bearzoti & S. D'angelo Neto, 1999. Estádios de desenvolvimento embrinário e localizaç ã o do embriã o zigó tico em sementes de citros. Pesq agrop bras 34: 1327–1333.
Ruiz, C., M. Paz Breto & M.J. Asíns, 2000. A quick methodology to identify sexual seedlings in citrus breeding programs using SSR markers. Euphytica 112: 89–94.
Tatum, J.H., R.E. Berry & C.J. Hearn, 1974. Characterization of Citrus cultivars and separation of nucellar and zygotic seedlings by thin layer chromatography. Proc Florida State Hort Soc 87: 75–81.
Teich, A.H. & P. Spiegel-Roy, 1972. Differentiation between nucellar and zygotic citrus seedlings by leaf shape. Theor Appl Gen 42: 314–315.
Teó filo Sobrinho, J., 1991. Propagaç ã o dos citros. In: O. Rodriguez, F. Viégas, J. Pompeu Jr. & A.A. Amaro (Eds.), Citricultura brasileira I, pp. 181–301. Fundaç ã o Cargill, Campinas.
Torres, A.M., R.K. Soost & U. Diedenhofen, 1978. Leaf isozymes as genetic markers in citrus. Am J Bot 65: 869–881.
Zar, J.H., 1999. Biostatistical Analyses. Prentice Hall, New Jersey.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Carlos de Oliveira, A., Novac Garcia, A., Cristofani, M. et al. Identification of citrus hybrids through the combination of leaf apex morphology and SSR markers. Euphytica 128, 397–403 (2002). https://doi.org/10.1023/A:1021223309212
Issue Date:
DOI: https://doi.org/10.1023/A:1021223309212