Karyotyping Melandrium album, a dioecious plant with heteromorphic sex chromosomes

Abstract

and NEGRUTIU, I. 1990. Karyotyping Melandrium album, a dioecious plant with heteromorphic sex chromosomes. Genome, 33: 556-562. Mitotic metaphase chromosomes of Melandrium album obtained from root protoplasts were studied. Morphologically, the chromosomes were either metacentrics or submetacentrics. They were classified into three distinct groups: group A comprising six pairs of autosomal metacentrics, group B comprising five pairs of autosomal submetacentrics, and the sex chromosomes: X and Y. The X chromosome is a metacentric (r = 1.44), which accounts for more than 14% of the genome. The Y chromosome is a metacentric with, virtually, equal arms (r = 1.09) and accounts for 21 % of the genome, being the largest of the complement. The Y:X ratio was 1.4. Ethidium bromide, caffeine, and vinblastine were used to obtain a better resolution and higher frequency of satellited chromosomes 7q and 9p. The proposed karyotype of M. album is 2n = 24, XX, s(7q;9p) for female and 2n = 24, XY, s(7q;9p) for male plants. Nucleolus organizer regions (NORs) were present at the telomeric sites of three chromosome pairs: 7q, 9p, and lop. The NORs were polymorphic, particularly between the nonhomologous chromosomes. The in situ hybridization technique localized the rRNA genes on four chromosome pairs: 5p, 7q, 9p, and lop. The discrepancy between the NORs and the hybridization signals was probably due to the fact that NORs were restricted only to transcriptionally active rRNA genes. It was concluded that for a complete description and characterization of rRNA genes, both NOR detection and in situ hybridization techniques, as cpplementary methods, shouldfie e m p l y d . J I / J Key words: Melandrium album, karyotype, satellites, idiogram, nucleolus organizer regions, in situ hybridization. CIUPERCESCU, D. D., VEUSKENS, J., MOURAS, A., YE, D., BRIQUET, M., et NEGRUTIU, 1. 1990. Karyotyping Melandrium album, a dioecious plant with heteromorphic sex chromosomes. Genome, 33 : 556-562. Les chromosomes en metaphase mitotique de Melandrium album ont ete etudies dans des protoplastes de racines. Morphologiquement, ces chromosomes sont soit metacentriques, soit submetacentriques. 11s ont ete classes en trois groupes distincts : un groupe A comprenant six paires d'autosomes metacentriques, un groupe B constitue de cinq paires d'autosomes submetacentriques, et les chromosomes du sexe X et Y. Le chromosome X est un metacentrique (r = 1,44) representant plus de 14% du genome. Le chromosome Y est metacentrique avec bras virtuellement egaux (r = 1,09); il represente 21010 du genome, etant le plus gros du complement. Le ratio de X:Y est de 1,4. Du bromure d'ethidium, de la cafeine et du vinblastine ont ete utilises pour obtenir une meilleure resolution et une frequence plus elevee des chromosomes 7q et 9p, porteurs de satellites. Le caryotype propose pour le M. album femelle est 2n = 24, XX, s(7q;9p) et, pour le miile, 2n = 24, XY, s(7q;9p). Les regions organisatrices de nucleoles (RONs) ont occupe des sites telomeriques chez trois paires de chromoso...

Cytological Analyses in Melandrium album: Genome Size, C.hromosome Size and Fluorescence in situ Hybridization.

“…The locations of large rRNA genes completely agreed with those determined by in situ hybridization with a radioactive probe (Ciupercescu et al 1990). Sites of 5S rRNA genes were firstly detected in chromosomes of M. album.…”

Cytogeneticss of Some Aneupoloid Mutant forms ofSilene Latifolia L

“…3) and reguraly 11 and 13 bivalent configurations in diakinesis, metaphase and anaphase i ( Table 1). it is well known that from 99 studied specis of the genus Silene, 92 possessed 24 chromosomes in their somatic cells and only two species possessed 20 chromosomes (2). the results obtained by cytological investigations and in situ hzbridization -FiSh (Table 1 and Fig.…”

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Short Communication: Cytological studies on black orchid hybrid (Coelogyne pandurata Lindley)

“…The plates were considered for the karyotype analysis in each species in the present investigation Chromosome size can be determined by measuring the length of the chromosome arm. The chromosome shape was established on the recommendation for varying values of r (Ciupercescu et al 1990). …”