Full text in pdf format
Chromosome number and secondary constriction variation in 51 accessions of a citrus germplasm bank
Marcelo GuerraI; Andrea PedrosaI; Ana Emilia Barros e SilvaI; Maria Tereza Marquim CornélioI; Karla SantosI; Walter dos Santos Soares FilhoII
IDepartamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brasil. Send correspondence to M.G.
IICentro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, EMBRAPA, Cruz das Almas, BA, Brasil.
ABSTRACT
The mitotic chromosomes of 51 citrus accessions from the Centro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, Cruz das Almas, BA, Brazil, were analyzed. The sample included representatives of 20 Citrus species, one of Poncirus and seven hybrids. All accessions showed 2n = 18 without any evidence of numerical variation. The most clearly variable karyotype feature was the number and position of secondary constrictions (SECs). In 19 accessions the SECs were not identified, mainly due to the degree of chromatin condensation. In the remainder they varied in number from one to three per karyotype. They were found in the proximal region of one of the three largest chromosome pairs, in the terminal /subterminal region of a smaller chromosome or, more seldom, terminally in a larger chromosome. Only in a few cases were such constrictions observed simultaneously in both homologues of the same chromosome pair. The high variability of this karyotype feature maybe due to the activation of this region in the previous interphase but may also indicate a high structural variability and heterozygosity of citrus germplasms.
Keywords: Chromosome number; constriction; citrus germplasm.
REFERENCES
Agarwal, P.K. (1987): Karyotype of Citrus tamurana (Tan.). Chrom. Inf. Serv. 42: 3-5.
Cameron, J.W. and Soost, R.K. (1969). Characters of new populations of Citrus polyploids, and the relation between tetraploidy in the pollen parent and hybrid tetraploid progeny. Proc. First Int. Citrus Symp. 1: 199-205.
Esen, A. and Soost, R.K. (1971). Unexpected triploids in Citrus: Their origin, identification, and possible use. J. Hered. 62: 329-333.
Esen, A., Soost, R.K. and Geraci, G. (1979). Genetic evidence for the origin of diploid megagametophytes in Citrus. J. Hered. 70: 5-8.
Favarger, C. (1978). Philosophie des comptages de chromosomes. Taxon 27: 441-448.
Frahm-Leliveld, J.A. (1965). Cytological data on some wild tropical Vigna species and cultivars from cowpea and asparagus bean. Euphytica 14: 251-270.
Frost, H.B. (1925a). The chromosomes of Citrus. J. Washington Acad. Sci. 15: 1-3.
Frost, H.B. (1925b). Tetraploidy in Citrus. Proc. Natl. Acad. Sci. LISA 2: 535-537.
Guerra, M. (1983). 0 uso do corante Giemsa na citogenética vegetal: comparação entre a coloração simples e o bandeamento. Ciênc. Cult. 35: 190-193.
Guerra, M. (1987). Cytogenetics of Rutaceae IV. Structure and systematic significance of interphase nuclei. Cytologia 52: 213-222.
Guerra, M. (1993). Cytogenetics of Rutaceae. V. High chromosomal variability in Citrus species revealed by CMA/ DAPI staining. Heredity 71: 234-241.
Guerra, M., Kenton, A. and Bennett, M.D. (1996). rDNA sites in mitotic and polytene chromosomes of Vigna unguiculata (L.) Walp. and Phaseolus coccineus L. revealed by in situ hybridization. Ann. Bot. 78: 157-161.
Hutchinson, D.J. and Barrett, H.C. (1981). Tetraploid frequency in nucellar seedlings from single trees of Carrizo and Troyer Citrus hybrids. Proc. Int. Soc. Citric. 1: 27-29.
Ito, Y., Omura, M. and Nesumi, H. (1993). Improvement of chromosome observation methods for Citrus. In: Techniques on Gene Diagnosis and Breeding in Fruit Trees (Hayashi, T., Omura, M. and Scott, N.S., eds.). FIRS, Tsukuba, pp. 31-38.
Iwamasa, M. and Nito, N. (1988). Cytogenetics and the evolution of modern cultivated Citrus. Proceedings of the sixth International Citrus Congress (Goren, R. and Mendel, K., eds.). Margraf Scientific Books, Weikersheim, pp. 265275.
Krug, C.A. (1943). Chromosome numbers in the subfamily Aurantioideae with special reference to the genus Citrus. Bot. Gaz. 104: 602-611.
Krug, C.A. and Bacchi, O. (1943). Triploid varieties of Citrus. Hered. 34: 277-283.
Lacadena, J.R., Cermeno, M.C., Orellana, J. and Santos, J.L. (1988). Nucleolar competition in Triticeae. In: Kew Chromosome Conference III (Brandham, P., ed.). HMSO, London, pp. 151-165.
Liang, G.L. (1988). Studies on the Giemsa C-banding patterns of some Citrus and its related genera. Acta Genet. Sin. 15: 409-416.
Lin, B.-Y. (1987). Número cromossômico de exemplares da família Bromeliaceae. Rev. Bras. Frutic. 9: 49-55.
Matsuyama, T., Akihama, T., Ito, Y., Omura, M. and Fukui, (1996). Characterization of heterochromatic regions in 'Trovita' orange (Citrus sinensis Osbeck) chromosomes by the fluorescent staining and FISH methods. Genome 39: 941-945.
Miller, D.A., Dev, V.G., Tantravahi, R. and Miller, O.J. (1976). Suppression of human nucleolus organizer activity in mouse-human somatic hybrid cells. Expl. Cell Res. 101: 235-243.
Moscone, E.A., Loidl, J., Ehrendorfer, F. and Hunziker, A.T. (1995). Analysis of active nucleolus organizing regions in Capsicum (Solanaceae) by silver staining. Am. J. Bot. 82: 276-287.
Naithani, S.P. and Raghuvanshi, S.S. (1963). Cytogenetical studies in Citrus. Part I. Genetica 33: 301-312.
Oiyama, I., Okudai, N. and Takahara, T. (1981). Ploidy levels of seedlings obtained from 2x X 4x crosses in Citrus. Proc. Int. Soc. Citric. 1: 32-34.
Raghuvanshi, S.S. (1962a). Cytogenetical studies in genus Citrus. Citrus assamensis. Caryologia 15: 143-149.
Raghuvanshi, S.S. (1962b). Cytogenetical studies in genus Citrus. IV. Evolution in genus Citrus. Cytologia 27: 172188.
Sato, S., Ohta, S. and Kuroki, Y. (1980). Heteromorphic appearance of acrocentric nucleolus organizer regions in Nothoscordum fragrans. Cytologia 45: 87-96.
Schubert, I. and Wobus, U. (1985). In situ hybridization confirms jumpingnucleolar organizing regions in Allium. Chromosoma 92: 143-148.
Sellito-Boaventura, Y.M. and Pio, R.M. (1989). Análise cito-genética em três cultivares de laranja doce (Citrus sinensis (L.) Osbeck). Rev. Bras. Genet. 12: 117-126.
Sharma, A.K. and Bal, A.K. (1957). Chromosome studies in Citrus. I. Agron. Lusit. 19: 101-126.
Swingle, W.T. and Reece, P.C. (1967). The botany of Citrus and its wild relatives. In: The Citrus Industry, Vol. I., History, World Distribution, Botany and Varieties (Reuter, W., Weber, H.J. and Batchelor, L.D., eds.). University of California Press, Berkeley, pp. 190-430.
Tanaka, T. (1954). Species problem in Citrus (Revisio aurantiacearum IX). Japanese Soc. Promotion Sci. Ueno, Toldo, pp.152.
Wakana, A., Iwamasa, M. and Uemoto, S. (1981). Seed development in relation to ploidy of zygotic embryo and endosperm in polyembryonic Citrus. Proc. Int. Soc. Citric. 1: 35-39.
Wei, W.N., Chen, Y.C., Li, R.T.L. and Duan, I.C. (1988). Studies on the evolution of Citrus based on karyotype and Giemsa patterns. Acta Hort. Sin. 15: 222-228.
Yonenaga-Yassuda, Y., Assis, M. de F.L., Kasahara, S., L'Abbate, M. and Souza, M.J. (1983). Nucleolar organizer regions in Akodon arviculoides (Cricetidae, Rodentia): evidence for the activity of rDNA genes in both X chromosomes of females. Cytogenet. Cell Genet. 35: 143-147.