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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.

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.

Brazil is the world's largest producer of common bean. Knowledge of the genetic diversity and relatedness of accessions adapted to Brazilian conditions is of great importance for the conservation of germplasm and for directing breeding programs aimed at the development of new cultivars. In this context, the objective of this study was to analyze the genetic diversity, population structure, and linkage disequilibrium (LD) of a diversity panel consisting of 219 common bean accessions, most of which belonging to the Mesoamerican gene pool. Genotyping by sequencing (GBS) of these accessions allowed the identification of 49,817 SNPs with minor allele frequency > 0.05. Of these, 17,149 and 12,876 were exclusive to the Mesoamerican and Andean pools, respectively, and 11,805 SNPs could differentiate the two gene pools. Further the separation according to the gene pool, bayesian analysis of the population structure showed a subdivision of the Mesoamerican accessions based on the origin and color of the seed tegument. LD analysis revealed the occurrence of long linkage blocks and low LD decay with physical distance between SNPs (LD half decay in 249 kb, corrected for population structure and relatedness). The GBS technique could effectively characterize the Brazilian common bean germplasms, and the diversity panel used in this study may be of great use in future genome-wide association studies.

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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

Ophrys iricolor and O. mesaritica are a pair of morphologically similar, closely related sexually deceptive orchids from the eastern Mediterranean. Ophrys iricolor is known to be pollinated by Andrena morio males and the specific pollinator of Ophrys mesaritica is determined as Andrena nigroaenea. Amplified fragment length polymorphism revealed O. iricolor and O. mesaritica to be genetically intermixed on the whole, although populations of O. iricolor and O. mesaritica in geographical proximity are strongly differentiated, suggesting that specific pollinators locally differentiate these taxa. Based on the available biological data and the system of pollinator attraction operative in Ophrys, we hypothesize that O. mesaritica may have arisen from O. iricolor by pollinator shift and that this is more probable than scenarios invoking hybridization as a result of mispollination by rare, non-specific flower visitors or specifically attracted insects.