Ricardo A. Lombello

Chromosomal studies and evolution in Sapindaceae

Summary Chromosome numbers and chromosomal ideograms were obtained for the Sapindaceae forest climbers Serjania caracasana, S. fuscifolia, S. meridionalis and Urvillea laevis (tribe Paulliniae) and the cerrado shrub Talisia obovata (tribe Melicocceae). Cytological preparations were obtained by Giemsa technique. Serjania and Urvillea showed 2n = 24, with chromosome length varying from 1.2 to 6.3I1m, large in relation to other Sapindaceae genera. Most chromosomes were submetacentric in Serjania and met acentric in Urvillea. The literature shows no interspecific variation of chromosome number in the genus Serjania, but it did occur in Urvillea. Talisia obovata showed 2n = 32, with small chromosomes (1.0 to 2.1I1m). A revision of chromosome numbers in 40 genera and 122 species showed great variation between species of Sapindaceae (2n= 14 to 2n=96). There is a small overlap of chromosome number between climbers and shrubs/trees: 74% of climbers so far studied have 2n=20, 22 and 24, and 82% of non-climbers have...

Malpighiaceae: correlations between habit, fruit type and basic chromosome number

A familia Malpighiaceae apresenta diferentes tipos de habito, frutos e caracteres citogeneticos. Em geral, especies lianas sao consideradas as mais derivadas, seguidas, respectivamente, pelas arbustivas e arboreas. O presente estudo propoe para Malpighiaceae uma relacao entre a variacao do numero cromossomico basico e a derivacao do habito trepador e da morfologia dos frutos. Para estabelecer esta relacao analisamos todas as contagens de cromossomos ja relatadas para a familia Malpighiaceae, sendo que a frequencia relativa destas contagens foi calculada para todos os generos estudados. Esta comparacao mostrou a predominância de numeros cromossomicos baseados em x=5 ou 10 na sub-familia Malpighioideae, predominantemente composta por lianas com frutos alados, enquanto que especies de outros habitos, com frutos nao alados, apresentaram contagens baseadas em x=6, considerado o numero basico menos derivado para a familia, predominante na sub-familia Byrsonimoideae. Baseados em consistentes dados estatisticos, e tambem na origem monofiletica da familia, admitimos a hipotese de que as derivacoes do habito e dos tipos de fruto estao diretamente relacionadas com a variacao do numero cromossomico na familia Malpighiaceae.

Heterochromatin and rDNA sites in Coffea L. chromo- somes revealed by FISH and CMA/DAPI II: C. canephora cv. Apoata ˜, C. salvatrix and C. sessiliflora

Abstract Cytogenetic studies in coffee species present a lack of information caused by some cytological characteristics, such as small chromosomes, symmetric karyotypes and the remarkable genetic homogeneity presented by the genus Coffea. Cytomolecular techniques based on in situ hybridization brought up new possibilities to improve the knowledge of cytogenetic characters and cytological processes involved in speciation of taxa with these cytological features. In the present work we analyzed one cultivar (C. canephora cv. Apoatã) and two wild diploid species (C. sal-vatrix and C. sessiliflora) of the Coffee Germplasm Bank of IAC attempting to cytogenetic characterization. Chromosome banding with fluorochromes DAPI and CMA3 and in situ hybridization with specific probes for rDNA sites 18S-5.8S-26S (probe pTa71) and 5S (probe pScT7) were carried out. For C. salvatrix and C. sessiliflora the CMA3 positive bands agreed with the in situ hybridized rDNA sites in number, size and position. The little variation in number and length of the rDNA sites between species of coffee is discussed.

Heterochromatin and rDNA sites in Coffea L. chromosomes revealed by FISH and CMA/DAPI. I: C. humilis, C. kapakata, C. sp. Moloundou and C. stenophylla

Abstract The study of coffee species with conventional cytological techniques have been facing problems caused by its similar karyomorphology. Moreover the genus Coffea L. presents a great genetic homogeneity. New possibilities were brought up by the employment of cytomolecular techniques, based on in situ hybridization. In the present work we analyzed four wild diploid species (C. humilis, C. kapakata, C. sp. Moloundou and C. stenophylla) of the Coffee Germplasm Bank of IAC attempting to cytogenetic characterization. Chromosome banding with fluorescent staining DAPI and CMA3 and in situ hybridization with specific probes for rDNA sites pTa71 and pScT7 were used. Only for C. stenophylla we observed positive DAPI band. For C. kapakata and C. stenophylla the CMA3 positive bands present resemblance with the in situ hybridized sites in number, size and position. Although we observed few variations in the number and size of the evidenced chromosomal regions, these data are sufficient for karyotype distinguishing in the four studied species. The present results reinforce the importance of chromosome mapping by banding techniques and in situ hybridization in order to characterize species with similar karyomorphology.

Reproductive biology and cytology of Hypericum brasiliense Choisy (Hypericaceae).

This is the first study of reproductive biology and cytology carried out with Hypericum brasiliense, a species with medicinal properties and potential agronomic interest. Three populations of H. brasiliense collected at Southeastern Brazil were studied. The results indicate that H. brasiliense is preferentially allogamous, self-compatible, facultative apomitic and anemophilous. Male sterility was observed in about 50% of individuals from the three populations. Anatomical studies evidenced structural abnormalities in anthers of male sterile flowers, showing enlarged tapetal cells and thick secretion deposits on the tapetal cell surfaces that may cause nutritional deficit for pollen mother cells. In cytogenetic studies several haploid chromosome numbers were observed like n = 4, 8, 9, 11, 16 and 17, including the presence of multivalents and micronuclei in tetrads, indicating the occurrence of abnormalities in the meiotic process of H. brasiliense. Despite these meiotic abnormalities the pollen viability and in vitro pollen germination rate observed in fertile flowers may be considered high. The diploid chromosome number 2n = 16 was observed, and the chromosomes in metaphase were small and similar. Fluorochrome staining techniques using DAPI and CMA3 were applied, with no positive bands observed.

Cytogenetics of twelve species of Malpighiaceae A. Juss. from Southeastern Brazil

Abstract The family Malpighiaceae shows a great chromosomal number diversity, with polyploidy and disploidy between and within species. Cytological studies have played an important role in the taxonomy of Malpighiaceae. In the present work we studied twelve species and present the chromosome numbers and for seven of them karyomorphological characters and chromosomal ideograms. The chromosomes are predominantly small and metacentric. No meiotic abnormalities were found, and they presented a high viable pollen index. We analyzed the relationship between the taxonomic distribution of taxa and the distribution of chromosomal numbers in Malpighiaceae species. The sub-family Malpighioideae presents chromosome numbers based on x=5 and the subfamily Byrsonimoideae presents numbers based on x=6. The basic number x=5 for Malpighiaceae is a new proposal, supported by some counts for the genera Banisteriopsis, Heteropterys, Peixotoa and Tetrapterys.