Searching for intraspecific chromosomic variation in Passiflora L. species.

Comparative cytogenetic studies are very useful in the characterization of different accessions of the same plant. The aimed of this study was search for intraspecific karyotypic variability in three species of the Passiflora genus using chromosomal conventional techniques (Giemsa staining and Fluorochromes base-specific) and molecular cytogenetic technique as Fluorescent in Situ Hybridization (FISH). The diploid character was observed in all plants analyzed by conventional staining being 2n = 18 as chromosomes number. The base-specific heterochromatin only showed GC-rich blocks on satellites and nucleolar organizer regions, but no intraspecific variation was found on CMA3+/DAPI− blocks, except for the two P. tholozanii accession, where the accession from Manaus showed five chromosomes with CMA3+/DAPI− separate blocks from where the blocks of the other accession were found. The CMA3+/DAPI− blocks showed relation to 45S rDNA located by FISH with variation only between P. tholozani accession. The other accessions from P. nitida and P. coccinea showed no quantitative differentiation on CMA3+/DAPI− blocks and 45S rDNA sites. Telomeric sites for all species were Arabidopsis-type and were limited to terminal sites suggesting chromosomal stability. The low intraspecific variation reinforces the need of developing other new chromosomal marker for cytogenetic mapping and increase the resolution on the chromatin visualization. [ABSTRACT FROM AUTHOR]