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Hypochaeris is thought to have arrived in South America by dispersal over the Atlantic Ocean from NW Africa during the Pliocene or Pleistocene. We used amplified fragment length polymorphism (AFLP) to unravel specific limits and relationships in the South American group of Hypochaeris (c. 45 species). The Moroccan endemic Hypochaeris angustifolia, which is sister to the entire South American group, was used as outgroup. Our AFLP analysis comprises 415 individuals from 32 South American species and is based on six primer combinations with 670 fragments scored. It provides important information for the delimitation of species and detection of closely related species pairs or groups. Most species are monophyletic and supported with > 90% bootstrap proportion. Hybridization is suggested between Hypochaeris chillensis and H. microcephala in Brazil. The internal nodes (or "backbone") of the tree are not highly supported, but six major phylogenetic groups (also showing similarity in distribution and growth form) center around Hypochaeris apargioides, H. chondrilloides, H. microcephala, H. pampasica, H. sessiliflora, and H. tenuifolia. These results suggest that rapid migration into different geographical regions played an important role in the initial diversification of Hypochaeris in South America.

The genetic relationships among 81 maize accessions consisting 79 landraces and two improved varieties, maintained by farmers in southern Brazil were investigated using Random Amplified Polymorphic DNA (RAPD). Thirty-two highly informative primers amplified 255 markers of which 184 (72.2%) were polymorphics. Based on the RAPD markers, a dendrogram was constructed using the UPGMA method. The range of genetic similarity was from 0.78 to 0.91. The molecular data grouped the accessions into two main clusters, which were correlated according to kernel colors. Small clusters were seen associated to characteristics, such as kernel morphology. The analysis of the molecular data revealed that maize management adopted by small-scale farmers has contributed to the maintenance of genetic variability and since field isolation is a regular practice, variety identities have been preserved. These results will be useful to establish and maintain a germplasm collection of landrace maize and may guide us in designing strategies that maximize the utility of maize genetic resources.

In an attempt to delineate the area of origin and migratory expansion of the highly successful invasive weedy species Hypochaeris radicata, we analysed amplified fragment length polymorphisms from samples taken from 44 populations. Population sampling focused on the central and western Mediterranean area, but also included sites from Northern Spain, Western and Central Europe, Southeast Asia and South America. The six primer combinations applied to 213 individuals generated a total of 517 fragments of which 513 (99.2%) were polymorphic. The neighbour-joining tree presented five clusters and these divisions were supported by the results of Bayesian analyses: plants in the Moroccan, Betic Sierras (Southern Spain), and central Mediterranean clusters are all heterocarpic. The north and central Spanish, southwestern Sierra Morena, and Central European, Asian and South American cluster contain both heterocarpic (southwestern Sierra Morena) and homocarpic populations (all other populations). The Doñana cluster includes two homocarpic populations. Analyses of fragment parameters indicate that the oldest populations of H. radicata are located in Morocco and that the species expanded from this area in the Late Quaternary via at least three migratory routes, the earliest of which seems to have been to the southwestern Iberian Peninsula, with subsequent colonizations to the central Mediterranean area and the Betic Sierras. Homocarpic populations originated in the southwestern Iberian Peninsula and subsequently spread across north and central Spain, Central Europe and worldwide, where they became a highly successful weed.

Inter-simple sequence repeat (ISSR) markers were used to evaluate genetic divergence among eight Coffea species and to identify the parentage of six interspecific hybrids. A total of 14 primers which contained different simple sequence repeats (SSR) were used as single primers or combined in pairs and tested for PCR amplifications. Two hundred and thirty highly reproducible fragments were amplified, which were then used to estimate the genetic similarity and to cluster the Coffea species and hybrids. High levels of interspecific genetic variation were revealed. The dinucleotide motif (GA) 9 T combined with other di-tri-and tetra-nucleotides produced a greater number of DNA fragments, mostly polymorphics, suggesting a high frequency of the poly GA microsatellite motifs in the Coffea genomes. The genetic similarity ranged from 0.25 between C. racemosa and C. liberica var. dewevrei to 0.86 between C. arabica var. arabica and Hybrid N. 2. The C. arabica species shared most of its markers with five of the six hybrids suggesting that it is the most likely candidate as one of the progenitors of those hybrids. These results revealed that ISSR markers could be efficiently used for genetic differentiation of the Coffea species and to identify the parentage of Coffea interspecific hybrids.

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The genus Mikania, which belongs to the tribe Eupatorieae of the family Compositae , is a group of herbaceous plants comprising about 300 species distributed in the tropical and sub tropical areas of the American continent and Asia . Barroso (1958) has found 150 species of Mikania distributed along all the Brazilian regions , many of those species being endemic.No karyological studies of this genus are available , and in some species only chromosome number has been recorded (Mitra 1947, Gaiser 1954, Mangenot and Mangenot 1958 , 1962, Turner et al. 1962. Mitra and Datta 1967, Turner et al. 1967, Baquar 1967-1968 , Sharma and Sakar 1967-1968, Coleman 1968, Nevling 1969, Powell and King 1969, King et al . 1976, Turner et al. 1979, Nauman 1981, Mathew and Mathew 1983Strother 1983 andWaisman et al. 1984). The present paper gives a detailed karyomorphological study of six species of the genus Mikania. ResultsThe karyotype of six species are presented in Fig. 1. The chromosomes are classified in two groups on the basis of the secondary constriction.The first group consisted on one pair of chromosomes with a secondary constriction in the long arm of the longest pair in the com plement. This was observed in M. cordifolia, M. glomerata, M. laevigata, M. trinervis and M. viminea. M. micrantha has two pairs of chromosomes with a secondary constriction in the long arm. The second group consisted of chromosomes without a secondary constriction. In each group the chromosomes were classified in M, m, sm and st, following the nomenclature of