The heterochromatin banding patterns in the karyotypes of 17 species belonging to 15 genera of Rutaceae subfamily Aurantioideae (= Citroideae) were analyzed with the fluorochromes chromomycin (CMA) and 4'-6-diamidino-2-phenylindole-2HCl (DAPI). All species were diploids, except one tetraploid (Clausena excavata) and two hexaploids [Glycosmis parviflora agg. (aggregate) and G. pentaphylla agg.]. There are only CMA/DAPI bands, including those associated with the nucleolus. Using recent cpDNA (chloroplast DNA) sequence data as a phylogenetic background, it becomes evident that generally more basal genera with rather plesiomorphic traits in their morphology, anatomy, and phytochemistry exhibit very small amounts of heterochromatin (e.g., Glycosmis, Severinia, Swinglea), whereas relatively advanced genera from different clades with more apomorphic characters display numerous large CMA bands (e.g., Merrillia, Feroniella, Fortunella). Heterochromatin increase (from 0.7 to 13.7%) is interpreted as apomorphic. The bands are mostly located in the larger chromosomes and at telomeric regions of larger arms. However, one of the largest chromosome pair has been conserved throughout the subfamily with only very little heterochromatin. The heterochromatin-rich patterns observed in different clades of Aurantioideae appear quite similar, suggesting a kind of parallel chromosomal evolution. In respect to the current classification of the subfamily, it is proposed to divide Murraya s.l. (sensu lato) into Bergera and Murraya s.s. (sensu stricto) and to place the former near Clausena into Clauseneae s.s. and the latter together with Merrillia into Citreae s.l. The subtribes recognized within Clauseneae s.s. and Citreae s.l. appear heterogeneous and should be abandoned. On the other hand, the monophyletic nature of the core group of Citrinae, i.e., the Citrus clade with Eremocitrus, Microcitrus, Clymenia, Poncirus, Fortunella, and Citrus, is well supported.

Most species of Citrus and related genera display a similar karyotype with 2n = 18 and a variable number of terminal heterochromatic blocks positively stained with chromomycin A(3) (CMA(+) bands). Some of these blocks are 45S rDNA sites, whereas others may correspond to the main GC-rich satellite DNA found in several Citrus species. In the present work, the distribution of the 45S rDNA and the main satellite DNA isolated from C. sinensis (CsSat) were investigated by in situ hybridization in seven species of Citrus, two species of closely related genera (Fortunella obovata and Poncirus trifoliata) and four species of the subfamily Aurantioideae, which were less related to Citrus (Atalantia monophylla, Murraya paniculata, Severinia buxifolia, and Triphasia trifolia). In Citrus, Fortunella, and Poncirus, most CMA(+) bands colocalized only with CsSat sites, whereas others colocalized only with rDNA sites. However, some of these species displayed a few CMA(+) bands that colocalized with sites of both probes and other CMA(+) bands that did not colocalized with any of the probes. On the other hand, in the four species less related to Citrus, no CsSat signal was found on chromosomes. On Southern blot, the CsSat probe hybridized with genomic DNA from Citrus, Fortunella, and Poncirus at high stringency only, while under the less stringent conditions, it also hybridized with distantly related species. Therefore, CsSat sequences are the principal component of the heterochromatic blocks of Citrus, Poncirus, and Fortunella, whereas CsSat-like sequences seem to be widespread in the subfamily Aurantioideae. These data further suggest that the variable number of terminal CMA(+) bands observed on chromosomes of Citrus and related genera are probably the consequence of amplification or reduction in the number of CsSat-like sequences distributed on chromosome termini, paralleled by mutation and homogenization events, as proposed by the library hypothesis.

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RESUMO -(Citogenética de Angiospermas coletadas em Pernambuco -V).Foram analisadas 33 espécies. entre nativas e introduzidas, pertencentes a 20 famílias de angiospermas ocorrentes no Estado de Pernambuco. A caracterização cariotípica da maioria das espécies foi baseada no número e morfologia cromossômica, padrão de condensação de cromossomos profásicos e estrutura de núcleo interfásico. Cinco espécies tiveram seus números cromossômicos determinados pela primeira vez. sendo e las: Cereus jWl/acoru (2n =22). Clitoria fairchildiana (2n=22), Eugel/ia luschl/athial/a (2n=22 ), Lical/ia tOlllel/tosa (2n =22) e Sl'olldias IIIhemsa (n= 16). No caso de Licania tOlllelllosa esta é a primeira citação de número cromossômico para o gênero. Das outras 28 espécies, três (Cecropia cf palma ta. 2n=26: Cril/ulII erubescel/s, 2n=70: e Schil/us terebelllifolius. 2n=28) apresentaram números cromossômicos diferentes dos registrados previamente na literatura.Palavras-chave -número cromossômico, núcleo interfásico. angiospermas ABSTRACT -(Cytogenetics of Angiosperms coll ected in the state ofPernambuco -V). Thirty three native and introduced species from 20 families of angiosperms collected in the State of Pernambuco were analysed. The karyotype description of the majority of the species was based on chromosome number and morphology. condensation pattern of prophase chroll1osoll1es as well as interphase nuclear structure. ln five species (Cereusjalllacaru, 2n=22; C/itoriafairchildial/a. 2n=22: Eugel/ia lusc!lIlathial/a, 2n=22; Lical/ia tomeI/tosa, 2n=22: and Spondias ruberosa , n=16) the chromosome number is reported here for the first time. ln the case of Licallia tOl/lel/to.m. this is also the first report for the genus. All10ng the other 28 species, three (Cecropia cf palmata, 2n=26: Crilllllll eruhescel/s, 2n=70; and Schil/llS terebelllifolius. 2n=28) showed chromosoll1e nllmbers different from what has previollsly been reported. Kcy words -chromosome nllmber. interphase nucleus. angiosperll1sIntrodução o número cromossômico é um dos parâ-metros mais utilizados para a caracterização citológica de uma espécie. Aliado a outros caracteres citológicos, auxilia no entendimento das I Auxílios BNB . FACEPE e CNPq alterações genéticas envolvidas na evolução do grupo, assim como na delimitação taxonômica das espécies. No caso de espécies cultivadas, a análise citogenélica, tanto com técnicas convencionais quanto moleculares, pode ser muito útil em

The mitotic chromosomes of 51 citrus accessions from the Centro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, Cruz das Almas, BA, Brazil, were analyzed. The sample included representatives of 20 Citrus species, one of Poncirus and seven hybrids. All accessions showed 2n = 18 without any evidence of numerical variation. The most clearly variable karyotype feature was the number and position of secondary constrictions (SECs). In 19 accessions the SECs were not identified, mainly due to the degree of chromatin condensation. In the remainder they varied in number from one to three per karyotype. They were found in the proximal region of one of the three largest chromosome pairs, in the terminal/subterminal region of a smaller chromosome or, more seldom, terminally in a larger chromosome. Only in a few cases were such constrictions observed simultaneously in both homologues of the same chromosome pair. The high variability of this karyotype feature may be due to the activation of this region in the previous interphase but may also indicate a high structural variability and heterozygosity of citrus germplasms
Foram analisados 51 acessos de citros do banco ativo de germoplasma do Centro Nacional de Pesquisa de Mandioca e Fruticultura Tropical (CNPMF/EMBRAPA), em Cruz das Almas, Bahia. A amostra incluiu representantes de 20 espécies de Citrus, uma de Poncirus e sete híbridos interespecíficos. Todos os acessos mostraram 2n = 18 sem nenhum indício de alteração numérica. A característica cariotípica mais claramente variável foi o número e posição das constrições secundárias (SECs). Em 19 acessos não foi possível localizar as SECs devido principalmente ao grau de condensação cromossômica. Nos demais acessos elas variaram em número de um a três e estavam localizadas na região proximal de um dos três maiores pares cromossômicos, na região terminal-subterminal de um dos pares de tamanho médio ou, mais raramente, em um dos cromossomos maiores. Em apenas uns poucos casos essas constrições foram observadas simultaneamente em ambos os homólogos de um par cromossômico. A alta variabilidade dessa característica cariotípica pode em parte ser devida à ativação diferencial dessa região na interfase anterior, mas pode também estar relacionada à grande heterozigosidade estrutural cromossômica conhecida em espécies de citro

Mitotic and meiotic chromosomes of several populations of Eurysternus caribaeus (Coleoptera: Scarabaeidae) were analysed through conventional staining, C-banding, base-specific fluorochromes, silver nitrate staining and fluorescent in situ hybridization (FISH). All specimens showed 2n = 8 in their karyotypes, with a neo-XY sex system (Y is a submetacentric and X a metacentric) and three pairs of submetacentric autosomes. The analysis of constitutive heterochromatin (CH) revealed small blocks located in the centromeric region of all chromosomes which do not present positive staining under the fluorochromes CMA 3 and DAPI. Silver nitrate staining revealed that the nucleolar organizer region (NORs) is associated with the sex chromosomes. The FISH technique revealed that rDNA sites in the X and Y are different in size. Data from different populations indicate that the diploid number reduction (2n = 8) observed in E. caribaeus is established and presumably has preceded the dispersion of this species. Moreover, this reduction occasioned the translocation of rDNA sites to the sex chromosomes, X and Y, an uncommon pattern in Scarabaeidae that was observed for the first time by the FISH in this work.

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Determination of the chromosome base number of a taxon is fundamental to understanding karyotypic variation and its implications for the evolution of that group. This usually requires careful evaluation of cytological literature and robust phylogenetic support. The base number for the family Rutaceae (x = 9 or x = 18) has long been the subject of debate. Here, we analyzed the banding pattern, rDNA sites, and genome size of Dictyoloma vandellianum, subfamily Cneoroideae, the sister group of the remaining Rutaceae, and revised critical points about the chromosome base number of the family. We found that this species has n = 9, which differs from the n = 18 possessed by other cytologically known Cneoroideae species. Thus, n = 9 occurs in the main clades of Rutaceae and is the most probable base number of the family. The hypothesis of x = 18 as the base number is no longer sustainable, although n = 18 is very common in Rutaceae. Moreover, the fluorescent banding pattern and the relatively large genome size (1C = 1.3 pg) of D. vandellianum suggest that its chromosomal organization is highly divergent from Aurantieae, the only large Rutaceae clade where species with n = 9 are greatly dominant.