Tribe Cestreae is monophyletic with three genera: Cestrum, Sessea, and Vestia. Karyotypically, it is outstanding within Solanaceae by several features: (1) basic number x = 8, (2) large chromosome sizes, (3) complex heterochromatin patterns, (4) occurrence of B-chromosomes (Bs) in Cestrum with particular banding patterns and rDNA sites distribution, and (5) absence of Arabidopsis-type telomeres. Seventeen South American Cestreae species from the three genera were studied using fluorescence in situ hybridization (FISH) with ribosomal DNA regions (5S and 18-5.8-26S) as probes, with the aim of recognizing specific or group-specific chromosomal markers and analyzing karyotype diversity in a systematic and evolutionary context. The first chromosome number report for Cestrum euanthes, C. kunthii, C. lorentzianum, and C. tomentosum is included. Variation in number and distribution of rDNA loci was observed among the species, concerning both As and Bs chromosomes. Despite the constancy of the karyotype and numbers of rDNA loci, the mapping of 18-5.8-26S and 5S rDNA loci allowed to differentiate Cestreae genera and species groups within Cestrum, highlighting the importance of these markers as cytotaxonomic character in this tribe.

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A karyotypic study on South American representatives of the Morelloid and Dulcamaroid clades of Solanum was conducted to contribute to a better understanding of their relationships. Mitotic chromosomes of 26 species were examined (13 of which were previously unknown). All taxa presented 2n = 2x = 24 and had small chromosomes (less than 4 μm long) with the exception of S. crispum. Most species displayed symmetrical karyotypes, being 78% and 69% m, 19% and 25% sm and 3% and 6% st for the Morelloid and Dulcamaroid clades, respectively. Solanum crispum (Dulcamaroid clade) was unique by having mostly sm chromosomes and S. sinuatirecurvum (Morelloid clade) stood out with four st pairs and an exclusive pair of satellites in long arms. Solanum tripartitum was the sole entity exhibiting an sm pair with satellites. Most examined species of these clades resulted karyologically indistinguishable, based on conventionally stained mitotic chromosomes. Molecular analyses are needed to gain a better knowledge of the possible karyoevolutionary trends of both clades.

L. STIEFKENS & G. BERNARDELLOMitotic chromosome numbers and karyotypes of species in two sections of Lycium (Solanaceae) from the American continent were determined in 23 populations. Both species in the small South American section Schistocalyx were examined: Lycium ciliatum and three varieties of L. chilense had diploid (2n=24) as well as tetraploid (2n=48) populations. Lycium ameghinoi from the small American section Sclerocarpellum was diploid with 2n=24. The basic number x=12 for the genus was confirmed. The karyotypes of these taxa were highly symmetrical: the chromosomes were metacentric or submetacentric with the formula: 11 m + 1 sm. Microsatellites were present in chromosome pair no. 1 and were attached to the short arms. As in other Lycium taxa already investigated, karyotypic features suggest that morphological differentiation in the group has not been accompanied by karyotype divergence.

Lycium is the only member of tribe Lycieae (Solanoideae, Solanaceae), and it has a cosmopolitan distribution with its greatest diversity in southern South America, southern Africa, and southwestern North America. To date, there has been no attempt to synthesize and evaluate the significance of the available cytogenetical data from a phylogenetic perspective, which is the objective of this study. Firstly, new data on 27 taxa from all its range of distribution (FISH in all of them, banding in 23, Feulgen technique in 14) were provided to fill gaps in the information. The chromosome numbers of L. australe, L. humile, and L. repens were recorded for the first time. Species showed x = 12 with different ploidy levels (mostly diploid or tetraploid), small chromosomes, and symmetrical karyotypes. Lycium fremontii and L. repens were outstanding for having the highest numbers reported for the genus: 10x and 11x, respectively. North American species showed comparatively longer chromosomes. Secondly, cytogenetical traits were mapped on a phylogenetic tree, using character mapping and ancestral states reconstruction, to understand the dynamics of the evolutionary changes. The main cytotaxonomical features were included: chromosome number, presence of polyploidy, total length of the haploid chromosome set, mean chromosome length, karyotype formula, A 1 and A 2 asymmetry indices, percentage of heterochromatin, number of CMA + /DAPI − NORs bands, and number and position of 5S and 18S-5.8S-26S sites. The mean chromosome length, total haploid chromosome length, number of 18S-5.8S-26S loci, number of CMA + /DAPI − NORs bands underwent comparatively few transitions compared with the ploidy level and number of 5S loci. The mapping of the characters on the phylogenetic tree showed that the most probable ancestral chromosome number was 2n = 24 with several independent polyploidization events and one pair of each rDNA locus. The most likely ancestral condition for the genus would be: diploid, with small chromosomes, scarce heterochromatin, asynteny of rDNA loci, and one pair of both 18S-5.8S-26S and 5S loci.

-Chromosomal analyses of several southern African Lycium species resulted in diploid (2n=24: L. amoenum, L. bosciifolium, L. ferocissimum, L. oxycarpum, L. tenue), tetraploid (2n=48: L. gariepense, L. strandveldense, L. hantamense), and hexaploid (2n=72: L. tetrandrum) counts. Chromosomes in all species were short (mean length = 2.00 μm; mean haploid genome length = 23.77 μm). Further, all species shared a highly symmetrical karyotype formula with 10 m pairs and 2 sm pairs, except L. bosciifolium with only one sm pair. The fi rst m pair had a terminal microsatellite on the short arms. Fluorescent chromosome banding patterns with CMA/ DAPI staining in the diploid species showed NOR-associated heterochromatin in the fi rst satellited pair. The tetraploids L. gariepense and L. hantamense had two chromosome pairs with a CMA + /DAPI -terminal band. Phylogenetic studies have shown that the southern African species are included in a monophyletic group including all Old World Lycium; these species are likely of recent origin and, despite ploidy differences, karyotypes are remarkably similar among species. Available data for South American, Asian, and southern African Lycium indicate that there is a common pattern of mostly m chromosomes in which a few cryptic chromosomal rearrangements may have occurred, suggesting that karyotypic orthoselection has preserved similar patterns among species. Thus, these data imply that speciation in Lycium was not accompanied by changes in chromosomal morphology.