Abstract
Nucleolar number variation has been investigated in root tip cells by cytologically determining the number of nucleoli per cell in autoploids and alloploids of Hordeum species, their haploids and interspecific hybrids. The nucleolus organisers in autoploid types of H. vulgare or H. bulbosum did not show any alterations irrespective of the ploidy level. The nucleolar number variation in these species results from a definite pattern of fusion and the maximum number of nucleoli per nucleus corresponds to the number of secondary constrictions. Nucleolus formation in alloploids and interspecific hybrids is impaired on some of the NORs, suggesting differential amphiplasty or nucleolar dominance. A comparison of nucleolar formation in the alloploid species (brachyantherum, arizonicum, procerum and parodii), their haploids, and the interspecific hybrids revealed different degrees of variation from the expected mean and maximum numbers of nucleoli. While the deviations in hybrids between alloploids (H. arizonicum and H. brachyantherum or H. procerum and H. brachyantherum) are marginal, nucleolar dominance is more pronounced in hybrids involving H. vulgare or H. bulbosum as one of the parents and is invariably associated with the disappearance of the secondary constriction(s) from the NOR(s) contributed by one of the parents, and the number of nucleoli is appropriately reduced.
Similar content being viewed by others
References
Anastassova-Kristeva M., Nicoloff H., Kunzel G. & Rieger R., 1977. Nucleolus formation in structurally reconstructed barley karyotypes with six satellite chromosomes. Chromosoma 62: 111–117.
Darvey N. L. & Driscoll C. J., 1972. Nucleolar behaviour in Triticum. Chromosoma 36: 131–139.
Doerschug E. B., 1976. Placement of genes for ribosomal RNA within the nucleolar organising body of Zea mays. Chromosoma 55: 43–56.
Doerschug E. B., Miksche J. P. & Stern H., 1976. DNA variation and ribosomal-DNA constancy in two Crepis species and the interspecific hybrid exhibiting nucleolar-organiser suppression. Heredity 37: 441–450.
Flavell R. B. & O'Dell M., 1979. The genetic control of nucleolus formation in wheat. Chromosoma 71: 135–152.
Givens J. F. & Phillips R. L., 1976. The nucleolus organiser region of maize (Zea mays L.): Ribosomal RNA gene distribution and nucleolar interactions. Chromosoma 57: 103–117.
Heitz E., 1931. Die Ursache der gesetzmäßigen Zahl, Lage, Form und Größc pflanzlicher Nukleolen. Planta 12: 775–884.
Keep E., 1962. Satellite and nucleolar number in hybrids between Ribes nigrum and R. grossularia and in their backcrosses. Can. J. Genet. Cytol. 4: 206–218.
Lange W. & Jochemsen G., 1976. Karyotypes, nucleoli and amphiplasty in hybrids between Hordeum vulgare L. and H. bulbosum L. Genetica 46: 217–233.
McClintock B., 1934. The relation of a particular chromosomal element to the development of the nucleoli in Zea mays. Z. Zellforsch. 21: 294–328.
Navashin M., 1934. Chromosome alterations caused by hybridization and their bearing upon certain general genetic problems. Cytologia (Tokyo) 51: 169–203.
Nicoloff H., Anastassova-Kristeva M., Rieger R. & Kunzel G., 1979: Nucleolar dominance' as observed in barley translocation lines with specifically reconstructed SAT chromosomes. Theor. appl. Genet. 55: 247–251.
Rajhathy T. & Morrison J. W., 1959. Cytogenetic studies in the genus Hordeum IV. Hybrids of H. jubatum, H. brachyanthcrum. H. vulgare and a hexaploid Hordeum species. Can. J. Genet. Cytol. 1: 124–132.
Rajhathy T., Morrison J. W. & Symko S., 1964. Interspecific and intergeneric hybrids in Hordeum. Barley Genetics I: 195–212.
Rieger R., Nicoloff H. & Anastassova-Kristeva M., 1979. ‘Nucleolar dominance’ in interspecific hybrids and translocation lines—A review. Biol. Zbl. 98: 385–398.
Subrahmanyam N. C., 1977. Haploidy from Hordeum interspecific crosses I. Polyhaploids of H. parodii and H. procerum. Theor. appl. Genet. 49: 209–217.
Subrahmanyam N. C., 1979. Haploidy from Hordcum interspecific crosses 2. Dihaploids of H. brachyantherum and H. depressum. Theor. appl. Genet. 55: 139–144.
Subrahmanyam N. C., 1980. Haploidy from Hordeum interspecific crosses 3. Trihaploids of H. arizonicum and H. lechleri. Theor. appl. Genet. 56: 257–263.
Subrahmanyam N. C., 1982. Species dominance in chromosome elimination in barley hybrids. Curr. Sci. 51: 28–31.
Subrahmanyam N. C. & AzadA. A., 1978a. Trisomic analysis of ribosomal RNA cistron multiplicity in barley (Hordeum vulgare L.). Chromosoma 69: 255–264.
Subrahmanyam N. C. & AzadA. A., 1978b. Nucleoli and ribosomal RNA cistron numbers in Hordeum species and interspecific hybrids exhibiting suppression of secondary constriction. Chromosoma 69: 265–273.
Subrahmanyam N. C. & Kasha K. J., 1973. Selective chromosomal elimination during haploid formation in barley following interspecific hybridisation. Chromosoma 42: 111–125.
Tsuchiya T., 1960. Cytogenetic studies of trisomics in barley. Jap. J. Bot. 17: 177–213.
Wallace H. & Langridge W. H. R., 1971. Differential amphiplasty and the control of ribosomal RNA synthesis. Heredity 27: 1–13.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Jessop, C.M., Subrahmanyam, N.C. Nucleolar number variation in Hordeum species, their haploids and interspecific hybrids. Genetica 64, 93–100 (1984). https://doi.org/10.1007/BF00120259
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00120259