Rosana Rodrigues

Divergência genética entre acessos de pimenta e pimentão utilizando técnicas multivariadas

Tecnicas multivariadas foram utilizadas para avaliar a divergencia genetica entre 56 acessos da colecao de germoplasma de Capsicum spp. da UENF. Foram utilizados onze descritores quantitativos propostos pelo International Plant Genetic Resources Institute, em um experimento conduzido em condicoes de campo, em Campos dos Goytacazes (RJ), no delineamento de blocos ao acaso com tres repeticoes e 10 plantas por parcela. A distância generalizada de Mahalanobis (D2) foi utilizada como medida de dissimilaridade. Foram aplicadas variaveis canonicas, metodo hierarquico do vizinho mais proximo, metodo de otimizacao de Tocher e projecao das distâncias no plano. As variaveis avaliadas foram comprimento e diâmetro do fruto, numero de sementes por fruto, peso medio do fruto, altura de planta, diâmetro da copa, peso de 1000 sementes, dias para florescimento, dias para frutificacao, numero de frutos por planta e peso de frutos por planta. Houve diferenca significativa entre os acessos para todos os descritores avaliados. Observou-se concordância entre todas as tecnicas multivariadas utilizadas e foi possivel separar os acessos em oito grupos distintos, indicando a existencia de variabilidade genetica entre os acessos. A maior distância generalizada de Mahalanobis foi 266,42. Observou-se que acessos tem potencial para serem utilizados como genitores em cruzamentos para obtencao de progenies com alta heterose. Pela analise das variaveis canonicas observou-se que os cruzamentos com maior potencial heterotico seriam 56x43, 34x08 e 59x41.

Variáveis multicategóricas na determinação da divergência genética entre acessos de pimenta e pimentão

Accessions of Capsicum maintained in germplasm banks are important not only for diversity preservation but also for plant breeding purposes. In this work the genetic divergence among Capsicum spp. accessions, were studied to verify the efficiency of dissimilarity measures and to discriminate genotypes in species, based on 13 multicategoric variables. The experiment was conducted in Campos dos Goytacazes, RJ, in randomized blocks with three replications testing 59 accessions, ten plants per plot, from November, 2001 to July, 2002. The following descriptors were considered: cotyledoneus leaf color; stem color, anther color; corolla color; number of flowers per axil; flower position; plant growth habit; fruit color at intermediate stage; fruit color at mature stage; fruit shape; fruit surface; seed color; number of locules; calyx annular constriction, and neck at base of fruit. The data were collected using mode of each descriptor following the IPGRI (1995) criteria. The data were analyzed according to Tocher optimization method, Nearest Neighbor, distance plotted in plain and discriminant analysis. Qualitative traits analyzed by Tochers method were efficient to differentiate among the species C. annuum var. annuum, C. annuum var. glabriusculum, C. chinense, and C. pubescens. This result confirms that qualitative descriptors considered essential for morphological and agronomic characterization must be used in germplasm bank management. Tochers method and Nearest Neighbor methods and distance plotted in plain showed resemblance and were efficient in clustering accessions with small genetic distance among them. Using functions of Andersons discriminant analysis it was possible to identify 100% of species and botanic variety used in this study.

Characterisation, immunolocalisation and antifungal activity of a lipid transfer protein from chili pepper (Capsicum annuum) seeds with novel α-amylase inhibitory properties

Lipid transfer proteins (LTPs) were thus named because they facilitate the transfer of lipids between membranes in vitro. This study was triggered by the characterization of a 9-kDa LTP from Capsicum annuum seeds that we call Ca-LTP(1) . Ca-LTP(1) was repurified, and in the last chromatographic purification step, propanol was used as the solvent in place of acetonitrile to maintain the proteins biological activity. Bidimensional electrophoresis of the 9-kDa band, which corresponds to the purified Ca-LTP(1) , showed the presence of three isoforms with isoelectric points (pIs) of 6.0, 8.5 and 9.5. Circular dichroism (CD) analysis suggested a predominance of α-helices, as expected for the structure of an LTP family member. LTPs immunorelated to Ca-LTP(1) from C. annuum were also detected by western blotting in exudates released from C. annuum seeds and also in other Capsicum species. The tissue and subcellular localization of Ca-LTP(1) indicated that it was mainly localized within dense vesicles. In addition, isolated Ca-LTP(1) exhibited antifungal activity against Colletotrichum lindemunthianum, and especially against Candida tropicalis, causing several morphological changes to the cells including the formation of pseudohyphae. Ca-LTP(1) also caused the yeast plasma membrane to be permeable to the dye SYTOX green, as verified by fluorescence microscopy. We also found that Ca-LTP(1) is able to inhibit mammalian α-amylase activity in vitro.

Divergência genética entre acessos de feijão-de-vagem de hábito de crescimento indeterminado

The search for snap bean cultivars presenting better production and quality is of crucial relevance due to the agricultural importance of this crop in the Rio de Janeiro State, Brazil. The determination of genetic divergence by multivariate analysis, through which several characters can be simultaneously dimensioned, is a rather advantageous technique since it allows to identify sources of variability, to evaluate the importance of characters for genetic divergence, and to identify genetic combinations with greater chances of success before crossings are performed. Multivariate analysis techniques allowed us to verify that common bean accessions presenting undetermined growth habits, originated from the UENF germplasm bank, show variability in relation to the evaluated traits. The Tocher optimization method allowed the formation of two groups; however, sub grouping by the same method has confirmed the occurrence of variability among group 1 accessions, from the formation of six subgroups. No relationship between genetic diversity and geographic origin of the accesses was found by using this method. The genetic divergence observed among the common bean accesses was quantified by three canonic variables, which explained around 79% of the total available variation. Discarding the variables of lower relative importance allowed us to identify the traits that have truly contributed to the determination of the genetic divergence: 100-seed weight, days for flowering, pod diameter, pod length, total number of beans and average number of beans. Accesses UENF-1429, UENF-1432, UENF-1442, UENF-1445 and UENF-1448 showed a good performance for the evaluated traits and genetic divergence, being indicated for use in breeding programs of snap beans.

Divergência genética em tomate estimada por marcadores RAPD em comparação com descritores multicategóricos

The estimation of genetic variability in a germplasm bank is important not only for the conservation of the genetic resources, but also for applications in plant breeding. The genetic divergence among 78 tomato accessions was studied, based on 74 RAPD markers. Also, a correlation between the molecular profile and 27 morphological and agronomic data was performed. Cluster analysis (UPGMA), used to study the data, resulted in 13 groups that were correlated with five descriptors (growth habit, leaf type, fruit color, locule number, and fruit shape). Some groups had particularities, such as group IV that assembled accessions with pear shape fruits; group VII, that clustered accessions with bacterial wilt resistance, and group IX, that gathered accessions with potato leaf type. Bootstrap analysis revealed few consistent clusters. The results showed a positive and significant correlation between the matrixes generated out of qualitative and molecular data (t = 14.02). Mantels correlation was highly significant, but with a low value (r = 0.39), which suggests that for a wise use of the germplasm bank accessions, both characterization, molecular and morphoagronomic, should be carried out.

Association between advanced generations and genealogy in inbred lines of snap bean by the Ward-Modified Location Model

The Ward-MLM strategy first proposed by Franco et al. (Crop Sci 38:1688–1696, 1998) is a useful method for analyzing genetic divergence for genealogical comparisons. However, this method has not yet been applied in conjunction with early generation testing (EGT) and single seed descent (SSD) procedures in autogamous plant species bred to advanced generations. In this study, we quantified the diversity of 120 recombinant snap bean lines from the F6:7 generation, advanced by SSD from the application of EGT in F2, to investigate the association between the grouping of lines and genealogy using the Ward-MLM method. Four F2 populations with high pod yields were selected from crosses among five genotypes. The segregating population was advanced to F6:7 by the SSD method. The traits of plant height, mean pod length, number of seeds per pod, mean number of days to flowering, mean pod fiber content and pod yield were evaluated. Based on the distribution of lines in the groups by the Ward-MLM approach, variability was verified in the four populations. Furthermore, the early selection in F2 did not limit the variability in the expression of genotypes with better agronomic performance. Thirty lines advanced by SSD for each population studied were sufficient to obtain superior genotypes. There was a relationship between the genealogy and groupings in F6:7, as evidenced by Group 1, G1, which contained the greatest number of lines from the crossing that were significantly enriched for their mean pod yield and Group 3, G3, which comprised the highest number of lines with a shorter plant type. These two traits, respectively, are the first and second most important traits for group stratification.

Aplicação de métodos de agrupamento na quantificação da divergência genética entre acessos de tomateiro

The quantification of the genetic divergence among accessions in a germplasm bank, based on descriptors for characterization, allows us to indicate promising parentals that can be used in breeding programs. In order to study the genetic divergence, multivariate analysis, including cluster methods has been used. The genetic divergence among tomato accessions was characterized and quantified, using cluster analysis. The experiment was carried out in 2001, in Rio de Janeiro State, Brazil, in field conditions. A randomized block design was used, with 70 accessions, three replications and 16 plants per plot. Twenty characterization and five evaluation descriptors were considered. There was significant difference among accessions for total number of fruits, total weight of fruits, mean number of fruits, mean weight of fruits, fruit length, fruit diameter, number of days for germination, days for fruit set, number of flowers per inflorescence, solid solubles, number of locules and days for flowering indicating the presence of genetic variability among accessions. Nearest neighbor method detected two groups, based on number of days for germination. Group 1 was formed by accessions with germination in 10 days while group 2 included accessions that germinated in seven days. Subgrouping from groups 1 and 2 detected seven and five subgroups for each group, respectively. Based on Tocher Method, ten groups were formed with agreement between Tocher and Nearest Neighbor.

Algoritmo de Gower na estimativa da divergência genética em germoplasma de pimenta

The estimation of genetic variability in germplasm collections is important not only for the conservation of genetic resources, but also for plant breeding purposes. Accessions in a germplasm bank are studied based on quantitative and qualitative descriptors. However, these data are rarely considered simultaneously in joint analyses. This work aimed to study the genetic diversity among 56 Capsicum chinense accessions coming from the Germplasm Collection of the Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF). We used 44 morpho-agronomic descriptors, 37 qualitative and seven quantitative, and the Growers algorithm for the joint analysis. We used a completely randomized design with three replications and three-plant plots. Plants grew in 5 L pots. There was phenotypic variability among the chili accessions studied, mainly in fruits. Marked differences were observed in size, shape, color and total soluble solids and vitamin C contents of fruits. We used UPGMA to perform the clustering, since it was the method with the higher cophenetic correlation coefficient (r = 0.82). Accessions felt into six classes. Gowers algorithm was more efficient in clustering when qualitative instead of quantitative data were considered. It indicates that qualitative data played a crucial role in explaining the observed groupings. Joint analysis of quantitative and qualitative data resulted in greater efficiency in the determination of genetic divergence among the accessions evaluated. Therefore, such analysis is definitely a viable and important tool for understanding the variability within germplasm banks.

Sources of resistance against the Pepper yellow mosaic virus in chili pepper

The Pepper yellow mosaic virus (PepYMV) naturally infects chili and sweet pepper, as well as tomato plants in Brazil, leading to severe losses. This work reports the reaction to the PepYMV of 127 Capsicum spp. accessions, aiming at identifying resistance sources useful in breeding programs. The experiment was carried out in a completely randomized design, with eight replications, in greenhouse conditions. Plants were protected with an insect-proof screen to avoid virus dissemination by aphids. Leaves of Nicotiana debneyi infected with the PepYMV were used as the inoculum source. Plants were inoculated with three to four fully expanded leaves. A second inoculation was done 48 hours later to avoid escapes. Only the youngest fully expanded leaf was inoculated. Two plants were inoculated only with buffer, as negative control. Symptoms were visually scored using a rating scale ranging from 1 (assymptomatic plants) to 5 (severe mosaic and leaf area reduction). Nine accessions were found to be resistant based on visual evaluation. Their resistance was confirmed by ELISA. Two resistance accessions belong to the species C. baccatum var. pendulum, while the seven other were C. chinense. No resistant accessions were identified in C. annuum var. annuum, C. annuum var. glabriusculum, and C. frutescens.

Antifungal and Other Biological Activities of Two 2S Albumin-Homologous Proteins Against Pathogenic Fungi

The aim of this study was to determine whether 2S albumins from Passiflora edulis f. flavicarpa and Capsicum annuum seeds inhibit growth, induce plasma membrane permeabilization and induce endogenous production of nitric oxide in different pathogenic and non-pathogenic yeasts. The 2S albumin from P. flavicarpa (Pf-Alb) inhibited the growth of Kluyveromyces marxiannus, Candida albicans and Candida parapsilosis. The membranes of these yeast strains were permeabilized in the presence of Pf-Alb. The Pf-Alb also inhibited the glucose-stimulated acidification of the medium by Saccharomyces cerevisiae and C. albicans cells, which indicates a probable impairment of fungal metabolism because the inhibition of acidification occurred at various Pf-Alb concentrations and pre-incubation times. The 2S albumin from C. annuum (Ca-Alb) inhibited the growth of the yeasts K. marxiannus, C. tropicalis, C. albicans and S. cerevisiae. These yeast strains exhibited NO induction in the presence of Ca-Alb and displayed cellular agglomeration, elongated cells and the induction of pseudohyphae. Pf-Alb and Ca-Alb at various concentrations also inhibited the glucose-stimulated acidification of the medium by S. cerevisiae cells. Our results indicate that the ability of antimicrobial plant proteins such as 2S albumins to induce microbial inhibition could be an important factor in determining pathogen virulence. Therefore, 2S albumins might be targets for the design of new antifungal drugs.