| Sumario: | The genomic constitutions of some Musa L. lines (bananas, plantains and artificial hybrids) were identified using molecular cytogenetic techniques. Double target in situ DNA:DNA hybridization to chromosome spreads using as probes, total genomic DNA isolated from diploid Musa lines of known AA (labelled with biotin-11-dUTP) and BB (labelled with digoxigenin-11-dUTP) genome constitution was carried out. The use of 60% acetic acid combined with heating over a flame gave high quality chromosome spreads free of cytoplasm for in situ hybridization. Total genomic A DNA labelled broad centromeric regions of all 22 chromosomes of the diploid line, Calcutta 4 ( M. acuminata Colla. ssp. burmanniccoides ; A genome) with some chromosomes showing stronger hybridization. Labelled DNA from the B genome hybridized strongly to the centromeric regions of all 22 chromosomes of Butohan 2 ( M. balbisiana Colla; B genome). The two satellited chromosomes of genome B labelled strongly with genomic A DNA. In situ hybridization of labelled A and B genomic DNA to metaphase chromosomes of triploid AAB and ABB cultivars discriminated between A and B genome chromosomes. The plantains Agbagba, Obino l'Ewai and Mbi Egome showed 22 genome A and 11 genome B chromosomes while the cooking bananas Bluggoe and Fougamou showed 11 genome A and 22 genome B chromosomes. Hybridization of labelled A and B genomic DNA to chromosomes of the hybrids showed that TMP2x 2829-62 has all 22 genome A chromosomes while TMPx 4698-1 has 33 genome A and 11 genome B chromosomes. In situ hybridization of labelled total genomic DNA to chromosomes has immense potential for identification of chromosome origin and can be used to characterize cultivars and hybrids produced in Musa breeding.
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