Gitai et al. 2015 (Conference Paper) Cryptanthus

Cytogenetic diversity, banding patterns and B Chromosomes in Cryptanthus

Author(s):—Jaílson Gitai, Geyner Cruz, R. Souza Paes, Ana Brasileiro-Vidal, Elton Leme & Ana Benko-Iseppon in Benko-Iseppon, A.M.; Alves, M. & Louzada, R. (2015) An overview and abstracts of the First World Congress on Bromeliaceae Evolution. Rodriguésia 66(2): A1-A66.

Publication:— (2015).

Abstract:—Bromeliaceae are generally known for conservation in chromosome numbers, with a prevalence of 2n=50, considered the diploid level, and different ploidy levels or still associated dysploid numbers as 2n=48. The genus Cryptanthus is an exception, since it presents lower numbers that are not multiples of the base number x=25 and is supposed to occupy a basal position within the family, being classified in the Bromelioideae subfamily. The unusual chromosome numbers 2n=34 and 36 are observed and in some species the presence of B chromosomes has been reported. In the present study, chromosome counts are presented for 10 species and first reports using fluorochrome staining CMA/DAPI (Chromomycin A3 and 4´,6-Diamidino-2-Phenylindole) and also FISH (Fluorescent In Situ Hybridization) with 45S rDNA probes is reported for the first time for the genus. The chromosome numbers found were: 2n= 32 in C. dineae and C. marginatus; 2n= 34in C. accaulis, C. bahianus, C. burle-marxii, C. aff. correia-araujoi, C. schwakeanus and Cryptanthus sp.09/2013, while B chromosomes were observed in C. bahianus (2n=34 + 1?3B) and C. praetextus (2n= 32+ 1?2B). Fluorochrome staining was carried out in C. burle-marxii, C. aff. correia-araujoi, C. dianae and Cryptanthus sp. 09/2013, evidencing CMA+/DAPI (GC-rich) terminal bands in two chromosome pairs and in one pair of Cryptanthus sp. 4972. FISH with 45S was performed in Cryptanthus sp. 4972 and (differentfrom the observation with fluorochrome staining) revealed two pairs associated with the NOR regions. For some species genome sizes were also estimated: [i] 2n=34: C. acaulis = 0.69 pg, C. bahianus = 0.38 pg, C. burle-marxii = 0.66 pg, C. aff. correia-araujoi = 0.83 pg, C. schwakeanus = 0.36 pg; [ii] 2n=32: C. dianae = 0.68 pg and C. marginatus = 0.70 pg; [iii] 2n=34 with B-chromosomes: C. praetextus (2n=32 + 1?2 B) = 0.68 pg. No association between genome size and chromosome number was evident. Considering the low content of satellite DNA (based on CMA/DAPI staining) the observed genome size variation (from 0.36 up to 0.83) is probably due to dispersed repetitive sequences. Variation in chromosome number and also in the number of NOR-bearing chromosomes indicate that dysploidy (possibly associated with hybridization processes) may be important processes in the evolution of the genus. Financial Support: CNPq and CAPES.

Keywords:—DNA Content; B Chromosome; Chromosome Banding.