Abstract The expansion of cowpea (Vigna unguiculata (L.) Walp.) crop has created new demands for its breeding programs. Knowledge of its genetic base is fundamental for choosing progenitors when conducting crosses. This study aimed to estimate the genetic base of Brazilian cowpea cultivars released between 1960 and 2022, in addition to identifying the origin of their cytoplasmic genes. Seventy-three cultivars were released in this period; however, only 41 had information about their original crosses. The ancestors CNC0434, Pitiúba and Seridó were used more frequently in crosses. They have also contributed with the highest frequency to the cultivars’ cytoplasmic genes. Therefore, although we found that between 2005 and 2022 there was a 30.95% increase in the contribution of different genotypes, we conclude that the genetic base of cowpea is narrow, and it is necessary to avoid crosses involving CNC0434, Pitiúba and Seridó in future breeding programs of this legume in Brazil. Vigna L. L (L. Walp. Walp 196 genes Seventythree Seventy three period however 4 CNC0434 CNC Therefore 200 202 3095 30 95 30.95 genotypes narrow Brazil (L 19 CNC043 20 309 3 9 30.9 1 CNC04 2 30. CNC0

Abstract Spondias mombin L. (Anacardiaceae) is an arboreal and allogamous fruit tree native from southern Mexico to southeastern Brazil, with great potential for economic exploitation. This study aimed to evaluate the structure and genomic diversity of yellow mombin accessions collected in nine locations in Brazil using Single Nucleotide Polymorphisms (SNP) markers. Significant genetic structure was observed in the discriminant analysis of principal components (DAPC) and dendrogram construction, in accordance with our hypotheses. The Mantel test identified a highly positive and significant correlation between geographic and genetic distances. The locations from the Amazon biome presented higher genetic diversity values when compared to those from the Atlantic Forest and Cerrado, which is expected considering the higher vulnerability of these biomes. However, although presenting greater genetic diversity, the Amazon biome showed positive inbreeding coefficients (F IS ) in three of the four locations, ranging from 0.0855 to 0.2421, indicating a potential risk of genetic erosion, possibly related to the increased degradation of this biome in recent decades. The results obtained contribute to the understanding of the distribution of genetic variation and conservation status of yellow mombin in Brazil. They could also be used as a subsidy for developing conservation strategies and the genetic improvement of this species. L Anacardiaceae (Anacardiaceae exploitation SNP (SNP markers DAPC (DAPC construction hypotheses distances Cerrado biomes However F 00855 0 0855 0.085 02421 2421 0.2421 erosion decades species 0085 085 0.08 0242 242 0.242 008 08 0.0 024 24 0.24 00 0. 02 2 0.2

Abstract Cotton is an essential worldwide commodity, and Brazil ranks fourth in world production and second in export. The present work aimed to gather the genealogies and estimate the genetic base of 109 Brazilian cotton cultivars released from 1932 to 2021. Twelve of the 68 ancestors identified contributed with 52.03% of the genes, and 33% of the cultivars resulted from the direct selection from landraces or old cultivars, evidencing a narrow genetic base. Over time, especially after 1990, the increases in the number of cultivars released and number of ancestors added to the breeding programs were driven by the need to reduce the cultivars' cycle for coexistence with pests and to make them suitable for mechanized cultivation in the new agricultural frontiers. However, Brazilian cotton cultivars still have a narrow genetic base, with the important participation of the ancestors CNPA SRI3, CKR 100W, C-77 and Express. commodity export 10 193 2021 6 5203 52 03 52.03 genes 33 time 1990 frontiers However SRI3 SRI 100W W C77 C 77 C-7 Express 1 19 202 520 5 0 52.0 3 199 C7 7 C- 20 52. 2

Abstract Hancornia speciosaGomes, a native fruit tree, plays an important socio-economic role in Brazil's traditional communities. The objective was to estimate the genetic structure of 176 individuals from eight locations in the Cerrado, Caatinga and Atlantic Forest biomes, based on six microsatellite markers. The analyzes revealed the formation of five population groups: A- Pernambuco, Paraíba and Sergipe (Atlantic Forest), B- Maranhão (Cerrado); both, var. speciosa, C- Bahia (Caatinga / Cerrado transition zone) and Ceará (Caatinga), D- Goiás (Cerrado) and E- Minas Gerais (Cerrado,) being groups C, D and E possibly var. pubescens. Most of the genetic variation is within the groups (65.61%, Fst = 0.34, p <0.001). Although group A had the highest Ho (0.66), it had a negative fixation index (f = -0.02), while the other had positive values. Our results revealed high levels of genetic diversity and provide support the development of more efficient conservation strategies for H. speciosa.

Resumo O Brasil é um país reconhecido por sua rica biodiversidade, mas também pela rápida perda de parte significativa de seus recursos genéticos in situ. Entre centenas de espécies nativas que apresentam grande potencial de exploração econômica, muitas ainda não são reconhecidas ou ainda não foram descritas. A mangabeira (Hancornia speciosa Gomes) é uma árvore frutífera que se encontra no início do processo de domestificação e possui enorme potencial econômico. No entanto, está sendo afetada pela erosão genética. Neste trabalho, são descritas cinco populações de mangabeira localizadas em distintas unidades de conservação, nas regiões Centro-Oeste e Nordeste do Brasil, onde ocorrem as variedades pubescens (típica) e speciosa. Mostramos que, mesmo em áreas protegidas, plantas de mangabeira não estão nas melhores condições de conservação. Como as áreas estão localizadas em biomas e em condições ambientais diversas, essas populações oferecem oportunidade para aprimorar o conhecimento sobre a espécie e para mapear suas áreas de ocorrência. Destacamos a relevância de manter as populações de mangabeira como reservatórios de recursos genéticos, o que potencializa a utilização da variabilidade genética desta espécie. Essas descrições destacam a importância significativa da manutenção de áreas protegidas como uma estratégia adequada para a conservação in situ.

Abstract Brazil, a recognized country for its rich biodiversity, is also known for the rapid loss of a significant part of its in situ genetic resources. Among hundreds of native species that have great potential for economic exploitation, many are not yet acknowledged or are yet to be described. The mangabeira (Hancornia speciosa Gomes) is a fruit tree at the begging of the domestication process and has enormous economic potential. However, it is being affected by genetic erosion. In this communication, we describe five populations of mangabeira located in distinct protected areas in the Midwest and Northeast regions of Brazil, where the varieties speciosa and pubescens occur. We show that even in protected areas, mangabeira plants are not in the best situation for conservation. The areas are located in diverse biomes and environmental conditions; therefore, such populations provide an opportunity to improve the knowledge about the species and map its areas of occurrence. We highlight the relevance of maintaining mangabeira populations as reservoirs of genetic resources, which leverage the utilization of the genetic variability of this species. These descriptions highlight the significant importance of maintaining protected areas as a suitable strategy for in situ conservation.

Abstract Repetitive DNA is an important component of eukaryotic genomes, accounting for more than 90% of the genome size of some species, including mobile elements and satellite DNA sequences. The aim of study was to characterize the genome of Hancornia speciosa Gomes using C-value genome size estimate and repetitive DNA sequences analysis. The genome size estimate was obtained by flow cytometry and the repetitive DNA sequences were accessed using graph-based clustering. Evolutionary relationships among species of Apocynaceae was obtained using reads of Catharanthus roseus L., Rhayza stricta Decne, and Asclepias syriaca L. from the NCBI and analyzed by graph-based clustering. The genome size estimates in two botanical varieties showed 2C-values ranging from 0.88 to 1.08 pg, indicating small genome size. Clusters representing repeats making up at least 0.01% of the genome revealed the proportion of repetitive DNA ranging from 19.87% (H. speciosa) to 51.674% (A. syriaca), of which the mobile elements were more abundant. Satellite DNA sequences were not found in H. speciosa and R. stricta, while at least one satellite was detected in C. roseus and A. syriaca, suggesting that the LTR retrotransposon Ty3/Gypsy/Chromovirus may have replaced the satellite DNA in H. speciosa and R. stricta.

Abstract Rice (Oryza sativa L.) is one of the most important crops in the world, and it is considered the primary source of nutritional layout in developing countries in Asia. The glutathione S-transferases (GSTs) superfamily confers to rice protection against biotic and abiotic stress, and herbicide resistance. However, the three-dimensional structure of a GST Tau class, is unsolved. The objectives of this work were to develop a reliable comparative model for the s-transferase glutathione class Tau 4 from rice, and simulate docking interactions, against herbicides bentazon and metsulfuron. Results showed that the predicted model is reliable and has structural quality. Ramachandran plot set 91.9% of the residues in the most favored regions. All complexes showed negative binding energies values; and metsulfuron docked to the glutathione tripeptide, and it represents a possible insilico evidence of glutathione conjugation with this herbicide.

RESUMO Para o aumento da produtividade em hortaliças de interesse agronômico, tem sido realizado o estudo da heterose, devido à superioridade dos híbridos, em relação aos genótipos de polinização livre. Objetivou-se estimar a heterose relativa em híbridos de melancia para os principais caracteres de interesse agronômico, visando ao desenvolvimento de futuras cultivares. Foram utilizados os genótipos 'JNY', 'ORA', 'KOD', 'SOL', 'CHG', 'PEA' e todos os híbridos possíveis entre eles, totalizando 36 tratamentos. Empregou-se o delineamento de blocos casualizados, com três repetições e parcelas com cinco plantas. Os genitores 'ORA', 'SOL', 'CHG' e 'PEA' apresentaram-se promissores para o desenvolvimento de híbridos de maior massa, enquanto 'JNY' e 'KOD' proporcionaram combinações com menor massa de fruto e sementes pequenas, indicando o seu potencial para o desenvolvimento de cultivares do tipo "mini". Os híbridos 'CHG x ORA' e 'ORA x CHG' foram promissores para atender a demanda de mercado por frutos maiores, enquanto 'KOD x JNY' e 'JNY x KOD' podem ser destinados à comercialização de frutos menores.

ABSTRACT In order to increase the yield of vegetables of agronomic interest, heterosis has been studied in view of the superiority of hybrids, if compared to genotypes obtained by free pollination. This study aimed to estimate the relative heterosis in watermelon hybrids, regarding the most important agronomic traits, in order to develop future cultivars. The genotypes 'JNY', 'ORA', 'KOD', 'SOL', 'CHG', 'PEA' and all hybrids among them were used, totaling 36 treatments. A randomized block design, with three replications and five-plant plots, was used. The genotypes 'ORA', 'SOL', 'CHG' and 'PEA' were promising for the development of watermelon hybrids with higher weight, whereas 'JNY' and 'KOD' provided combinations with lower fruit weight and smaller seeds, indicating their potential for the development of cultivars of the 'ice box' type. The hybrids 'CHG x ORA' and 'ORA x CHG' were promising to meet the market demand for larger fruits, while 'KOD x JNY' and 'JNY x KOD' could be targeted to the market of smaller fruits.

RESUMO: Psidium guineense Sw., conhecida popularmente como araçá, é uma fruteira pertencente à família Myrtaceae que tem ampla distribuição geográfica. Nos Estados do Nordeste Brasileiro ela ocorre principalmente na faixa litorânea e Zona da Mata. O fruto do araçazeiro tem sabor que lembra o da goiaba, ligeiramente mais ácido e de perfume mais acentuado, e sua exploração é feita de modo extrativista. As informações sobre esta espécie são escassas, o que dificulta a conservação dos recursos genéticos e sua exploração econômica. Neste trabalho foram estudadas a diversidade e estrutura genética de quatro populações de araçá, tendo sido avaliados um total de 114 indivíduos por meio de 18 loci isoenzimáticos que revelaram 28 alelos. A porcentagem de locipolimórficos () e o número médio de alelos por loco () nas populações foram 0,5 e 1,5, respectivamente. A heterozigosidade esperada (), que corresponde à diversidade gênica, variou entre 0,22 e 0,23, valores altos, principalmenteconsiderando-se que isoenzimas acessam a porção funcional do genoma. O índice médio de diferenciação () entre as populações foi de 0,015, portanto, as populações basicamente não diferem entre os locais amostrados. O índice de fixação () variou de -0,549 a -0,794 indicando ausência de endogamia e excesso de heterozigosidade nas populações. O fluxo gênico (Nm) estimado para os pares de populações variou de 3,23 a 20,77, valores que corroboram com a ausência de diferenciação observada entre estas.

ABSTRAT: Psidium guineense Sw, popularly known as araçá, is a fruit tree there is widely distributed in Brazil and belongs to the Myrtaceae family. In northeastern Brazil, araçá occurs along coast and in the Zona da Mata; its fruit looks like guava but is more acidic and has a stronger smell. There is a little information about this species, which increases the difficulty of conserving its genetic resources and exploiting araçá as an economic resource. The objective of this research was the evaluation of the genetic diversity and genetic structure of P. guineense from Pernambuco's Zona da Mata. One hundred and fourteen individuals and 18 isozyme loci were evaluated, showing 28 alleles. The percentage of polymorphic loci () and the average number of alleles per locus () were 0.5 and 1.5, respectively, in this population. The expected heterozygosity, which corresponds to the genetic diversity, ranged from 0.22 to 0.23, a high value when considering that isozymes mark access from the functional genome. The differentiation index among the population was () = 0.015; therefore, the populations were not different among the sampled places. The inbreeding values () ranged from -0.549 to -0.794, indicating an absence of inbreeding and a greater-than-expected heterozygosity in all the studied populations. The estimated gene flow (Nm) for a pair of this population ranged from 3.23 to 20.77, sufficient to avoid genetic differentiation among the population and in accordance with the values of genetic divergence found in this study.

O presente trabalho teve por objetivo estimar a base genética de cultivares brasileiras de arroz irrigado liberadas comercialmente no período de 1965 a 2012. As genealogias das cultivares foram obtidas com base em informações de folders de divulgação de cultivares, sites de internet, livros de registros de cruzamentos e artigos científicos. Os seguintes fatores foram calculados: contribuição genética relativa (RGC), contribuição genética acumulada (AGC), frequência (em porcentagem) de cada ancestral na genealogia (FAG), número de ancestrais que constitui cada cultivar (NAC), número de ancestrais responsáveis por 60%, 70%, 80% e 90% da base genética (NAGB) e número médio de ancestrais por cultivar (ANAC). As cultivares foram também agrupadas baseando-se no período de lançamento (1965-1980, 1981-1990, 1991-2000 e 2001-2012); para cada agrupamento, os fatores previamente citados também foram estimados. Um total de 110 cultivares foi estudado. Concluiu-se que a base genética das cultivares brasileiras de arroz irrigado é estreita.

The aim of this study was to estimate the genetic base of Brazilian irrigated rice cultivars released in the period from 1965 to 2012. The genealogies of the cultivars were obtained based on information from marketing folders, websites, crossings records, and scientific articles. The following factors were calculated: relative genetic contribution (RGC), accumulated genetic contribution (AGC), frequency (in percentage) of each ancestor in the genealogy (FAG), number of ancestors that constitute each cultivar (NAC), number of ancestors responsible for 60%, 70%, 80% and 90% of the genetic base (NAGB), and average number of ancestor per cultivar (ANAC). The cultivars were also grouped based on the period of release (1965-1980, 1981-1990, 1991-2000 and 2001-2012). For each grouping, the previously described factors were also estimated. A total of 110 cultivars were studied and it was concluded that the genetic base of Brazilian irrigated rice cultivars is narrow.

Hancornia speciosa Gomes é uma árvore frutífera nativa do Brasil, pertencente à família Apocinaceae, e é conhecida popularmente como Mangabeira. Seus frutos são amplamente consumidos in natura ou processados como sucos, sorvetes e geleias. O extrativismo e a intensa atividade antrópica no ambiente de ocorrência natural da Mangabeira, no Nordeste do Brasil, têm causado erosão genética na espécie e pouco se conhece sobre a estrutura genética das populações desta espécie. O objetivo deste trabalho foi avaliar a diversidade e a estrutura genética de populações naturais de H. speciosa var. speciosa. Utilizando 11 locos isoenzimáticos, avaliaram-se 164 indivíduos, amostrados em seis populações naturais localizadas nos Estados de Pernambuco e Alagoas, Nordeste do Brasil. Os resultados mostraram um alto nível de diversidade genética dentro da espécie (<img border=0 id="_x0000_i1032" src="/img/revistas/rbf/v34n4/a23img01.jpg">e = 0,36), sendo verificado que a maior parte da variabilidade genética se encontra dentro das populações, com pequena diferenciação entre as mesmas (<img border=0 id="_x0000_i1033" src="/img/revistas/rbf/v34n4/a23img02.jpg" align=absmiddle> = 0,081). A endogamia dentro das populações (<img border=0 id="_x0000_i1034" src="/img/revistas/rbf/v34n4/a23img03.jpg" align=absmiddle> = - 0,555) e entre elas (<img border=0 id="_x0000_i1035" src="/img/revistas/rbf/v34n4/a23img04.jpg" align=absmiddle > ou = -0,428) foi baixa, evidenciando ausência de endogamia e excesso de heterozigotos. O fluxo gênico estimado (<img border=0 id="_x0000_i1036" src="/img/revistas/rbf/v34n4/a23img05.jpg" align=absmiddle>) foi elevado, variando de 2,20 a 13,18, valores considerados suficientes para evitar os efeitos da deriva genética e a diferenciação genética entre as populações. As análises multivariadas indicam que há relação entre distância genética e espaço geográfico, hipótese esta que foi confirmada por uma análise de padrão espacial,utilizando o teste de Mantel (r = 0,3598; p = 0,0920) com 1.000 permutações aleatórias. O alto índice de diversidade genética nas populações indica potencial para a conservação genética in situ.

Hancornia speciosa Gomes is a fruit tree native from Brazil that belongs to Apocinaceae family, and is popularly known as Mangabeira. Its fruits are widely consumed raw or processed as fruit jam, juices and ice creams, which have made it a target of intense exploitation. The extractive activities and intense human activity on the environment of natural occurrence of H. speciosa has caused genetic erosion in the species and little is known about the ecology or genetic structure of natural populations. The objective of this research was the evaluation of the genetic diversity and genetic structure of H. speciosa var. speciosa. The genetic variability was assessed using 11 allozyme loci with a sample of 164 individuals distributed in six natural populations located in the States of Pernambuco and Alagoas, Northeastern Brazil. The results showed a high level of genetic diversity within the species (<img border=0 id="_x0000_i1026" src="/img/revistas/rbf/v34n4/a23img01.jpg" align=absmiddle>e= 0.36) seeing that the most of the genetic variability of H. speciosa var. speciosa is within its natural populations with low difference among populations ( <img border=0 id="_x0000_i1027" src="/img/revistas/rbf/v34n4/a23img02.jpg" align=absmiddle > or = 0.081). The inbreeding values within (<img border=0 id="_x0000_i1028" src="/img/revistas/rbf/v34n4/a23img03.jpg" align=absmiddle> = -0.555) and among populations (<img border=0 id="_x0000_i1029" src="/img/revistas/rbf/v34n4/a23img04.jpg" align=absmiddle> =-0.428) were low showing lacking of endogamy and a surplus of heterozygotes. The estimated gene flow ( <img border=0 id="_x0000_i1030" src="/img/revistas/rbf/v34n4/a23img05.jpg" align=absmiddle>m ) was high, ranging from 2.20 to 13.18, indicating to be enough to prevent the effects of genetic drift and genetic differentiation among populations. The multivariate analyses indicated that there is a relationship between genetic and geographical distances, which was confirmed by a spatial pattern analysis using Mantel test (r = 0.3598; p = 0.0920) with 1000 random permutations. The high genetic diversity index in these populations indicates potential for in situ genetic conservation.

The agro-morphological characterization is fundamental in order to provide information for plant breeding programs. The aim of the present study was to characterize 146 accessions of upland rice (Oryza sativa L.), based on qualitative and quantitative agro-morphological descriptors. The experiment was conducted in Recife, state of Pernambuco, Brazil, using a randomized block design with three replicates. Polymorphism was observed among 12 of 14 qualitative characters evaluated, whereas significant differences (p < 0.05) were observed for 11 of the 14 analysed quantitative traits. Genetic variance was higher than environmental variance and the average inheritability coefficients were above 80 % for all characters, which ensures the predominance of the genetic components in the differences observed among accessions. On the cluster analysis for qualitative traits the accessions were classified in two groups with a total of 18 duplicates, whereas for the quantitative traits three groups were obtained with few subgroups. The principal component analysis for quantitative traits showed great dispersion of the accessions. The most divergent group of accessions included the genotypes Mitsukasane, Mie, Tomoe mochi, Ooba kirishima and Nourin mochi 6, which showed a higher number of spicklets per plant. There is high variability among the rice accessions from the germplasm collection studied, which presents great importance for breeding programs or for genetic studies on this species.

A espécie S. mombin L. é uma árvore frutífera de origem americana pertencente à família Anacardiaceae . No Brasil, é encontrada nos mais variados tipos de vegetação, porém é mais freqüente na Mata Atlântica e na Floresta Amazônica. Destaca-se economicamente por seus frutos serem amplamente consumidos in natura ou utilizados na indústria, principalmente para fabricação de polpas, geléias, sucos e sorvetes. As folhas têm grande importância para a indústria farmacêutica, por possuírem propriedades antibacterianas. No Estado de Pernambuco, a cajazeira encontra-se amplamente distribuída na Zona da Mata, ocorrendo com menos freqüência no Agreste e Sertão. Neste trabalho, estudaram-se a diversidade e a estrutura genética de populações de cajazeiras na Zona da Mata do Estado de Pernambuco, Nordeste do Brasil, por meio da análise do polimorfismo isoenzimático obtido por eletroforese. Os resultados revelaram 100 % de polimorfismo para nove alelos, sendo que o número médio de alelos por loco<img src="/img/revistas/rbf/v31n1/a24car02.jpg" align="absmiddle"> foi de 2,4. A heterozigosidade esperada <img src="/img/revistas/rbf/v31n1/a24car01.jpg" align="absmiddle">variou de 0,530 a 0,574, e a heterozigosidade observada <img src="/img/revistas/rbf/v31n1/a24car03.jpg" align="absmiddle">variou de 0,572 a 0,735. Não se verificou endogamia nas populações, sendo que o valor médio de F IT foi de -0,175, intrapopulacional ( f ) variou de -0,08 a -0,37. A diferenciação entre as populações (F ST) variou de 0,006 a 0,028, sendo que o valor médio de 0,026 e, o fluxo gênico estimado entre as populações (Nm) foram altos (5,27). A população CG-IPA, que constitui a Coleção de Germoplasma do IPA, apresentou acima de 96% de identidade genética com as demais populações e, portanto, tem alta representatividade na diversidade existente na região.

Spondias mombin L. is a fruit tree from the American continent from the Anacardiaceae family. In Brazil it is common in different vegetation types but is more frequent in the Atlantic and Amazonian rainforests. It is economically important because of its fruits, which are widely consumed raw or processed as fruit jellies, juices and ice creams. The leaves have great importance in the pharmaceutical industry because of their antibacterial properties. In the state of Pernambuco, cajá tree is widely distributed in the Zona da Mata region and less frequently in the Agreste and Sertão areas. In this work diversity and genetic structure were studied in four populations of cajá tree from Pernambuco's Zona da Mata, Northeast Brazil, using isozymes polymorphism analyses from electrophoreses. The result showed 100% of polymorphism (P) for nine alleles <img src="/img/revistas/rbf/v31n1/a24car02.jpg" align="absmiddle"> and the average of alleles per locus s was 2.4. The expected heterozygosity <img src="/img/revistas/rbf/v31n1/a24car01.jpg" align="absmiddle">ranged from 0.530 to 0.574 and the observed heterozygosity <img src="/img/revistas/rbf/v31n1/a24car03.jpg" align="absmiddle">, from 0.572 to 0.735. It was not observed inbreeding and the average F IT was -0.175, whereas within population inbreeding (f) varied from -0.08 to- 0.37. The genetic divergence among the populations (F ST) ranged from 0.006 to 0.028 and the average was 0.026. The average of estimated gene flow (Nm) was high (5.27). The CG-IPA population, corresponding to the germplasm collection of IPA, showed more than 96% of genetic similarity with other populations; therefore, it is a good representative of the existent genetic diversity in the Zona da Mata region.

Visando caracterizar a diversidade genética entre espécies e populações de arroz selvagem da América do Sul, foram avaliadas 11 populações de Oryza glumaepatula, sete de O. grandiglumis, quatro de O. latifolia e uma população de O. alta, originárias do Brasil e Argentina. Foi conduzido um experimento em casa-de-vegetação em blocos ao acaso com 23 tratamentos. Vinte caracteres agro-morfológicos foram avaliados. Análises univariadas foram realizadas para 16 caracteres quantitativos, desdobrando-se o efeito de populações dentro de espécies. Diferenças significativas (p<0,001) entre espécies foram observadas para todos os caracteres bem como entre populações dentro de espécies. A mais variável foi O. glumaepatula seguida de O. latifolia. Análises de agrupamento e discriminante canônica confirmaram a separação das populações de O. glumaepatula das espécies tetraplóides, e a grande variação genética entre populações de O. latifolia. Diferenças morfológicas entre as três espécies tetraplóides parecem suficientes para classificá-las como espécies pelo menos na condição statu nascendi.

To characterize the genetic variability among species and populations of South American wild rice, eleven populations of Oryza glumaepatula, seven of O. grandiglumis, four of O. latifolia and one of O. alta, from Brazil and Argentina, were evaluated. A greenhouse experiment was conducted in completely randomized blocks with 23 treatments. Twenty morphoagronomic traits were assessed. Univariate analyses were performed with 16 quantitative traits with the partitioning of populations within species. Significant differences (p<0.001) between species were observed for all the traits as well as among populations within the species. The most variable was O. glumaepatula followed by O. latifolia. Multivariate discriminant canonical and cluster analyses confirmed the separation of the highly diverse O. glumaepatula populations from the tetraploid species, and the high genetic variation among O. latifolia populations. Morphological differences among the three tetraploid species seemed to be enough to ascribe them at least the condition of species in statu nascendi.

O arroz (Oryza sativa L.) é uma espécie autógama com taxa de cruzamento natural de até 3%, sendo as variações influenciadas pelos genótipos e ambientes. O objetivo deste trabalho foi avaliar a taxa e a distância de cruzamento natural entre as cultivares de arroz-de-sequeiro Guarani e IAC 201. O estudo foi desenvolvido nos municípios de Carpina e do Recife, no Estado de Pernambuco nos anos agrícolas de 2001 e de 2002 respectivamente. Na cultivar Guarani observa-se pilosidade nas folhas condicionada por alelos dominantes HLHL e essa característica foi utilizada como marcador morfológico. Já na cultivar IAC 201 não, por ser portadora dos alelos recessivos (hlhl). Os experimentos foram compostos por quatro blocos, constituídos de dez linhas circunscritas da cultivar em estudo, espaçados a 50 cm entre si, e no centro de cada bloco plantou-se a cultivar Guarani. A taxa e a distância de cruzamento natural foram avaliadas nas plantas provenientes das sementes da cultivar IAC 201, oriundas do cruzamento natural, expressando pilosidade nas folhas. Após a avaliação das plantas referentes às duas primeiras linhas do experimento desenvolvido em Carpina e das três primeiras linhas do experimento de Recife, constatou-se que apenas na primeira linha (0,5 m) houve plantas resultantes de cruzamento natural. Nessa distância, verificou-se que a taxa média de cruzamento natural de 0,30% em Carpina e de 0,35% no Recife.

Rice (Oryza sativa L.) is an autogamous species that shows natural crossing rates of up to 3%, where the variations are influenced by genotypes and environments. The present work aimed to evaluate the rates and distances of natural crossing between the upland rice cultivars Guarani and IAC 201. The study was done in the counties of Carpina and Recife, in the State of Pernambuco during the agricultural years of 2001 and 2002, respectively. The Guarani cultivar presents leaf pilosity conditioned by the dominant alleles HLHL and this character was used as a morphologic tracer. On the other hand, the IAC 201 cultivar does not show pilosity because it carries the recessive alleles (hlhl). The experiments were composed of four blocks, constituting of ten circunscribed rows of the cultivar under study, spaced 50 cm between themselves, and in the center of each block the Guarani cultivar was planted. The natural crossing rate and distance were evaluated in the plants resulting from the seeds of the IAC 201 cultivar from natural crossing, expressing pilosity in the leaves. After the evaluation of the plants arising from the first two rows of the experiment carried out in Carpina and the first three rows of the experiment done in Recife, it was concluded that in the first row (0.5 m) there were plants resulting from natural crossing. At this distance, the average crossing rate in Carpina was 0.30% while that in Recife was 0.35%.