Chromosome studies on Brazilian cerrado plants

Cerrado is the Brazilian name for the neotropical savanna, which occurs mainly in Brazilian Central Plateau, composed of herbaceous-subshrubby and shrubby-arboreal floras, both of which are heliophilous, highly diverse and regionally differentiated. Considering species distribution and chromosome numbers, some authors have proposed that the herbaceous-subshrubby flora of the neotropical savanna is quite old, while the shrubby-arboreal flora is derived from forests, a hypothesis that implies higher chromosome numbers in the savanna than in the forest. If, however, chromosome numbers are similar in the cerrado and in forests, both could be similarly old, indicating that bi-directional flow of flora occurred in the past. This paper presents data on chromosome numbers and microsporogenesis for 20 species in 13 families collected in the States of São Paulo, Goiás and Minas Gerais, providing previously unpublished data for Myrcia (Myrtaceae), Luxemburgia (Ochnaceae) and Hortia (Rutaceae). Meiosis proved to be normal, indicating regularity in the sexual reproductive process. Chromosome numbers varied from 2n = 18 (Allamanda angustifolia: Apocynaceae) to 2n = ca. 104 (Ouratea spectabilis: Ochnaceae), being low (20 < 2n < 30) in most of the species. Since similar numbers have been observed with forest species, it is not, at the moment, possible to support the hypothesis that cerrado species derived from the surrounding forests. Instead, we suggest the possibility of a bi-directional exchange of floristic elements between cerrado and forests during evolutionary time.Cerrado é a palavra que, no Brasil, designa a savana neotropical, com área nuclear no Planalto Central, constituída de uma flora herbáceo-subarbustiva e outra arbustivo-arbórea, ambas heliófilas, altamente diversificadas e regionalmente diferenciadas. Considerando a distribuição de espécies e de números cromossômicos, alguns autores propuseram que a flora herbáceo-subarbustiva da savanna neotropical seria bastante antiga, enquanto a flora arbustivo-arbórea seria derivada das florestas Atlântica e Amazônica, uma hipótese que implica na ocorrência de números cromossômicos mais altos no cerrado que nas florestas. Porém, se os números cromossômicos forem similares no cerrado e nas florestas, ambos os tipos de formação poderiam ser similarmente antigos, indicando que um fluxo florístico bidirecional entre o cerrado e as florestas teria ocorrido no passado. Este trabalho apresenta dados sobre números cromossômicos e microsporogênese de 20 espécies em 13 famílias, coletadas nos estados de São Paulo, Goiás e Minas Gerais, trazendo informações inéditas para Myrcia (Myrtaceae), Luxemburgia (Ochnaceae) e Hortia (Rutaceae). A meiose mostrou-se normal, indicando regularidade no processo reprodutivo sexual. Os números cromossômicos variaram de 2n = 18 (Allamanda angustifolia: Apocynaceae) a 2n = ca. 104 (Ouratea spectabilis: Ochnaceae), sendo baixos (20 < 2n < 30) na maioria das espécies. Como números cromossômicos similares têm sido encontrados também em espécies florestais, torna-se impossível, no momento, corroborar a hipótese de que espécies arbustivo-arbóreas do cerrado sejam derivadas de espécies das florestas limítrofes. Sugerimos que tenha havido uma troca bidirecional de elementos entre o cerrado e as florestas durante o tempo evolutivo.947955Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Gene Duplication in the Sugarcane Genome: A Case Study of Allele Interactions and Evolutionary Patterns in Two Genic Regions

Sugarcane (Saccharum spp.) is highly polyploid and aneuploid. Modern cultivars are derived from hybridization between S. officinarum and S. spontaneum. This combination results in a genome exhibiting variable ploidy among different loci, a huge genome size (~10 Gb) and a high content of repetitive regions. An approach using genomic, transcriptomic, and genetic mapping can improve our knowledge of the behavior of genetics in sugarcane. The hypothetical HP600 and Centromere Protein C (CENP-C) genes from sugarcane were used to elucidate the allelic expression and genomic and genetic behaviors of this complex polyploid. The physically linked side-by-side genes HP600 and CENP-C were found in two different homeologous chromosome groups with ploidies of eight and ten. The first region (Region01) was a Sorghum bicolor ortholog region with all haplotypes of HP600 and CENP-C expressed, but HP600 exhibited an unbalanced haplotype expression. The second region (Region02) was a scrambled sugarcane sequence formed from different noncollinear genes containing partial duplications of HP600 and CENP-C (paralogs). This duplication resulted in a non-expressed HP600 pseudogene and a recombined fusion version of CENP-C and the orthologous gene Sobic.003G299500 with at least two chimeric gene haplotypes expressed. It was also determined that it occurred before Saccharum genus formation and after the separation of sorghum and sugarcane. A linkage map was constructed using markers from nonduplicated Region01 and for the duplication (Region01 and Region02). We compare the physical and linkage maps, demonstrating the possibility of mapping markers located in duplicated regions with markers in nonduplicated region. Our results contribute directly to the improvement of linkage mapping in complex polyploids and improve the integration of physical and genetic data for sugarcane breeding programs. Thus, we describe the complexity involved in sugarcane genetics and genomics and allelic dynamics, which can be useful for understanding complex polyploid genomes

Cariotipo e sua analise numerica como subsidio a estudos taxonomicos e evolutivos de Phaseolus L. Vigna savi e Macroptilium (Bentham) urban-Leguminosae, Papalionoidacae

Orientador : George J. SheperdTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Foram feitos estudos citotaxonômicos em 18 espécies de Hacroptilium (Bentham) Urban, Phaseolus l. e Vigna Savi (leguminosae, P~pilionoideae): M. atropurpureum (D.C.) Urban, M. bracteatum (Nees & Mart.) Maréchal & Baudet,CBentham) CHoehne)Urban, M. lath~roides (l. ) Urban,M.M.er~throloma sabaraense V.P. Barbosa Fevereiro, P. acutifolius A. Gra~, P.anisotrichus Schlecht., P. coc~ineus l., P. filiformis Bentham,P. lunatus l. , P. vulgaris l., V. adenantha CG.F. Me~er)Marécha I , Mascherpa & Stainier, V. candida (Vellozo) Marécha 1,Mascherpa & Stainier, V. luteola CJacq.) Bentham, V. peduncularis CH.B.K.) Fawcet & Rendle, V. radiata (l.) Wilczek, V. umbel1ata (Thunb.) Ohwi & Ohashi e V. unguiculata Cl.> Walpers. Ideograma,cariótipo, fórmulas cariotípicas, comprimento total de cromatina (CTC) e índice TF% (simetria cariotípica) são apresentadas para cada espécie. ... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digitalAbstract: data, only 5.08n o, the average values showed high coe'icients o,variation (higher than 20n). There were a greõt overlapping o,TCl and TFn values among the species o, a genus and even among different genera. Evolutive tendencies were discussed basing on these data, concluding that there must have had an enlargement o, TCl and diminution of TFn for this group. The application of statistical tests. such as principal component anal~sis, linear discriminant anal~sis, and cluster anal~sis, did not allow the individualization of species or genera. Hacroptilium and Vigna showed some leveI of karyotype sfmilarity (KSI) both among species of each genus and between the two genera. ... Note: The complete abstract is available with the full electronic digital thesis or dissertations. ... Note: The complete abstract is available with the full electronic digital thesis or dissertationsDoutoradoDoutor em Ciências Biológica

Chromosome studies on Brazilian cerrado plants

Cerrado is the Brazilian name for the neotropical savanna, which occurs mainly in Brazilian Central Plateau, composed of herbaceous-subshrubby and shrubby-arboreal floras, both of which are heliophilous, highly diverse and regionally differentiated. Considering species distribution and chromosome numbers, some authors have proposed that the herbaceous-subshrubby flora of the neotropical savanna is quite old, while the shrubby-arboreal flora is derived from forests, a hypothesis that implies higher chromosome numbers in the savanna than in the forest. If, however, chromosome numbers are similar in the cerrado and in forests, both could be similarly old, indicating that bi-directional flow of flora occurred in the past. This paper presents data on chromosome numbers and microsporogenesis for 20 species in 13 families collected in the States of São Paulo, Goiás and Minas Gerais, providing previously unpublished data for Myrcia (Myrtaceae), Luxemburgia (Ochnaceae) and Hortia (Rutaceae). Meiosis proved to be normal, indicating regularity in the sexual reproductive process. Chromosome numbers varied from 2n = 18 (Allamanda angustifolia: Apocynaceae) to 2n = ca. 104 (Ouratea spectabilis: Ochnaceae), being low (20 < 2n < 30) in most of the species. Since similar numbers have been observed with forest species, it is not, at the moment, possible to support the hypothesis that cerrado species derived from the surrounding forests. Instead, we suggest the possibility of a bi-directional exchange of floristic elements between cerrado and forests during evolutionary time