02333naa a2200205 a 450000100080000000500110000800800410001910000150006024501000007526000090017552016480018465000180183265300110185070000180186170000150187970000280189470000220192270000280194477301550197216556852009-01-15       2008    bl uuuu     u00u1 u    #d1 aGUERRA, M.  aMolecular characterization of chromosomes of Poncirus trifoliata using different DNA sequences.  c2008  aIn order to get a first molecular  cytogenetic map of each chromosome of Poncirus trifoliata, we localized by fluorescent in situ hybridization (FISH)  several different probes. Chromosomes were firstly stained with the fluorochromes CMA and DAPI which allow the identification of heterochromatin as CMA+/DAPI- bands, dividing the nine chromosome pairs into three groups: two chromosome pairs bearing a proximal and a terminal  band (B type), four having only a single terminal band (D type) and three others without any band (F type). Sequential CMA/DAPI staining and FISH using the 5S and 45S rDNA probes showed that these two probes were always adjacent to each other. The 45S rDNA probe co-located with the proximal band of all B type chromosome and with the single band of one D chromosome. A satelite DNA sequence isolated from Citrus sinensis, using primers based on the 181 bp satelite sequence of C. ichangensis described by Beridze et al. (1992), hybridzed at all CMA+ bands except the rDNA sites and a single terminal band in a B chromosome, suggesting that this is the main satelite sequence of Citrus and Poncirus. Further, 24 BACs from a P. trifoliata genomic library were selected and hybridized in situ, including four BACs from the Ctv resistance gene region. Seven out of the 24 probes gave disperse signals, four did not give any signal and 13 produced single copy homozygous signals in seven of the nine chromosome pairs (two D pairs were not labeled). The four BACs from the Ctv region were located very close to each other at the smallest F chromosome type, precisely in the interstitial region of the more distended arm.  aBiotecnologia  aCitros1 aMORAES, A. P.1 aMIRKOV, E.1 aBRASILEIRO-VIDAL, A. C.1 aSILVA, A. E. B. e1 aSOARES FILHO, W. dos S.  tIn: INTERNATIONAL CITRUS CONGRESS, 11., 2008, Wuhan,China. Program and abstracts... Wuhan: The International Society of Citriculture, 2008. p. 25. 19.