Caroline Marques Castro

Genetic structure of annual ryegrass (Lolium multiflorum) populations estimated by RAPD

Annual ryegrass is a temperate climate annual foraging grass, grown mostly in the South of Brazil, especially in the state of Rio Grande do Sul. Despite its importance, little is known about its genetic diversity, both within and among the populations cultivated. This knowledge is of fundamental importance for developing breeding and conservation strategies. The aim of this study was to characterize the genetic diversity and structure of four populations of annual ryegrass. Three of the populations were located in Rio Grande do Sul and the fourth in Uruguay. RAPD markers were used to study the genetic diversity and structure of these populations. Analysis of 375 individuals sampled from the populations, using six RAPD primers, generated a total of 82 amplified bands. They included 73 polymorphic bands (89,02%). The value of the total genetic diversity index obtained, (0,71) was high, indicating the presence of wide genetic diversity in the four populations. Genetic structure analysis revealed that 98% of total diversity is intrapopulational, whereas interpopulational genetic diversity was only 2%. These results suggest that before these populations separated, they had gone through a period of gene exchange and, even after the separation event, gene frequency stayed at levels similar to the original levels, with no differential selection for these genes in the different cultivation areas.

Desempenho agronômico de clones elite de batata

The aim of this work was to verify the growth cycle, yield components and specific gravity of advanced potato clones as compared to the main varieties grown in Brazil. The experiment was carried on at the Embrapa Clima Temperado experimental field, in Pelotas, Rio Grande do Sul state, Brazil. Eight advanced potato clones developed by the Embrapa Potato Breeding Program, and two commercial cultivars were evaluated in the autumn season of 2011. A randomized complete block design with four replications was used, the plots being constituted by a line of 20 plants. Growth cycle was assessed 95 days after planting. Plants of each plot were harvested at 110 days, followed by evaluation of yield components and specific gravity. After checking for normality of error distribution, the data were submitted to analysis of variance and to means grouping by the Scott & Knott test. CL02-05, CL69-05, CL27-05 and 2197-15 clones showed higher commercial tuber number, percentage of commercial tubers and average tuber weight than the check varieties. CL02-05 clone showed, besides, the highest yield potential of commercial tubers of all four clones. CL69-05 and 2197-15 presented specific gravity and growth cycle similar to Asterix, but had higher yield potential and larger tuber size than it.

Molecular characterization of Butia capitata populations (Arecaceae) in Southern Brazil estimated by AFLP analysis

O genero Butia (Arecaceae) e um pequeno genero subtropical com especies no sul da America do Sul, considerado ornamental. Alem disso, seus frutos sao apreciados pelo sabor e aroma peculiares. Porem, no Rio Grande do Sul, as populacoes naturais sofrem com o avanco das atividades rurais e da construcao imobiliaria. O objetivo deste trabalho foi caracterizar oito populacoes de Butia capitata ocorrentes no Rio Grande do Sul atraves de marcadores moleculares do tipo AFLP. Pela analise molecular da variância, foi possivel verificar que 83,68% da variabilidade genetica sao atribuidos a variacao entre populacoes e 13,67% sao atribuidos a diferencas entre populacoes dentro de regioes. A analise comparativa entre as oito populacoes feita de duas a duas demonstrou que sao significativas as diferencas entre 15 populacoes, com media de 14,72% da variacao molecular atribuida as diferencas entre populacoes. Este resultado indica a presenca de variabilidade genetica distribuida entre todas as populacoes, sem subdivisao decorrente de isolamento geografico.

Genetic variability in surinam cherry populations originated from self-pollination and cross pollination, estimated by AFLP.

AFLP molecular markers were used aiming to study the genetic variability within and between Surinam cherry (Eugenia uniflora) populations, originated from self-pollination and open pollination of two selections (Pit 15 and Pit 52) of the Embrapa Clima Temperado collection. The objective was to achieve a better understanding about the reproduction mode of this species. Two progenies were obtained from each selection being one from self-pollination and another from open-pollination, resulting in four populations. The analysis was carried out in 18 individuals of each progeny and the two mother plants, totalizing 74 genotypes. Three AFLP primer combinations were used and the genetic similarity was calculated by Jaccard coefficient. Genetic variability within and between populations was estimated by AMOVA. The three primer combinations amplified 178 loci, of which 114 (64%) were polimorphic, considering all the genotypes. There was not a clear separation between the two progenies of the same mother plant. Larger polimorphism of AFLP markers was observed in the open-pollinated populations. The proportion of total genetic variability was significant, between populations from open-pollination, although smaller than the variability observed within populations. The Surinam cherry reproduction is based on both self-fertilization as well as cross-pollination. Nevertheless it is rather important to do further studies in order to determine which reproduction mode is the most efficient.

BRS Ana: cultivar de batata de duplo propósito

The genotype BRS Ana is a new potato cultivar adequate for French fries, with potential for processing into frozen French fries and flakes, released in 2007. It was developed by the Embrapa Potato Breeding Program (Embrapa Temperate Agriculture, Pelotas-RS; Embrapa Transference of Technology, Office of Canoinhas-SC; and Embrapa Vegetables, Brasilia-DF), based on tuber appearance and yield, specific gravity and French fries quality. Tubers are red-skinned, lightly rough, oval shaped with shallow eyes. The pulp is white. Cultivar BRS Ana has high yield potential. In the subtropical ecosystem, cultivar BRS Ana showed higher yield (31.2 t ha-1) than the most used cultivars in Brazil when grown in autumn, and did not differ from them in the spring. In the tropical ecosystem, under irrigation, BRS Ana did not differ from both control cultivars. It produced higher percentage of marketable tubers (55.6%) and average tuber weight (108.4 g) than the controls in the fall crop of subtropical ecosystem. In both ecosystems, cultivar BRS Ana presented high specific gravity (1.086) and dry matter content (19.7%). The sensorial analysis showed that cultivar BRS Ana is adequate for home made French fries as well as for industrial processing. It is moderately susceptible to late blight (Phytophthora infestans) and presents good resistance to early blight (Alternaria solani). The reaction to the tuber soft rot (Pectobacterium sp.) is similar to the most used cultivars. It has low seed degeneration conferred by moderate resistance to PVY and low incidence of PLRV. Susceptibility to tuber physiological disorders has not been observed. It seems that BRS Ana has lower fertilizer and water requirements than the most planted cultivars, meaning reduction of crop cost and risk. In the subtropical ecosystem, tuberization starts later in spring, therefore BRS Ana should be planted earlier in the season.

Tolerância ao frio do amendoim forrageiro

The yield of tropical perennial forages in temperate climate areas depends on its cold tolerance. The exposure of genotypes to temperatures below 2oC, under controlled conditions is an efficient methodology to predict cold tolerance, since it maintains homogeneous levels of cold. Due to absence of information related to cold tolerance of tropical forages, this experiment was developed aiming to evaluate the behavior of forage peanut exposed to temperatures below 2oC. The design adopted was completely randomized with 15 replications and two treatments: exposed and not exposed to cold. The traits measured were: number of leaves per stolon; thickness of stolon and number of new shoots. The results showed that the exposition of the forage peanut to a range of temperature from -1.0 to 1.3 °C, for 3 hours, causes cold stress in the plants, resulting in a reduction of the number of leaves per solon and stimulating the emergency of new shoots, but did not kill the plants.

Caracterização molecular de variedades crioulas de pimentas (Capsicum baccatum) com marcadores microssatélites

Currently, many landraces of C. baccatum are grown by farmers in Brazil. These populations are sources of genes for resistance or tolerance to abiotic and biotic stresses. However, most of these landraces are being lost due to genetic erosion caused by substitution of cultivars. In order to characterize and conserve landraces, since 2002 Embrapa Temperate Agriculture maintains an Active Germplasm Bank of Capsicum. This work has the objective to characterize landraces of C. baccatum using microsatellite markers. 20 accessions from the Active Germplasm Bank of Capsicum of Embrapa Temperate Agriculture were analyzed. DNA was extracted individually from young leaves collected from five plants of each accession. Eight microsatellite loci were analyzed. All loci were polymorphic. Molecular analysis of variance showed values of genetic diversity as 51.37% among accessions and 48.63% within the accessions. This fact showed the existence of segregation in many of these pepper landraces. The groups obtained by cluster analysis did not correlate with morphological fruit traits. Most of the genetic variability is found among different landraces, although there is also genetic variability within each accession.

Diversidade genética de Cucurbita pepo, C. argyrosperma e C. ficifolia empregando marcadores microssatélites

Genetic diversity of Cucurbita pepo, C. argyrosperma and C. ficifolia accessions evaluated through microsatellite markers Landraces of five domesticated species of Cucurbita are cultivated in southern Brazil. Among them C. argyrosperma and C. ficifolia are the least studied. Microsatellite markers are important for the molecular characterization of these two species, but there is a need for specific primers, not yet available. The aim of this study was to evaluate the transferability of primers and optimize the amplification of SSR loci in C. pepo, C. argyrosperma and C. ficifolia and also evaluate genetic diversity in different accessions of germplasm in these species. We used ten accessions of C. pepo, nine of C. argyrosperma and five of C. ficifolia from the Genebank of Cucurbitaceae from Embrapa Temperate Agriculture. DNA was extracted in bulk from the leaves of five individuals of each accession. 40 SSR primers developed for C. pepo were used. In C. pepo 35 primers (87.5%) amplified, in C. argyrosperma, 34 primers (85%), and in C. ficifolia , 32 primers (80%). The transferability of SSR loci in C. pepo to C. argyrosperma and C. ficifolia was 85 and 80% respectively. The transferability of SSR loci from C. pepo to C. argyrosperma and C. ficifolia was 85 and 80% respectively. Thus, the transferability rate of SSR loci developed for C. pepo to C. argyrosperma and C. ficifolia was high, indicating that they can be used in molecular characterization of these species.

Caracterização molecular de variedades crioulas de abóboras com marcadores microssatélites

Dentre as cinco especies de aboboras domesticadas, Cucurbita pepo apresenta a maior variabilidade para caracteristicas de fruto, como cor, formato e tamanho. O Banco Ativo de Germoplasma de Cucurbitaceas da Embrapa Clima Temperado conta com 61 acessos desta especie, todos estes, variedades crioulas cultivadas no sul do Brasil. Estas variedades crioulas fazem parte da cultura regional, na gastronomia, no artesanato e na ornamentacao de ambientes. O objetivo deste trabalho foi avaliar a variabilidade genetica entre e dentro de variedades crioulas de C. pepo cultivadas no Rio Grande do Sul, utilizando marcadores microssatelites. Foram avaliados 10 acessos de variedades crioulas de C. pepo. que apresentavam diferentes formatos e tamanhos de fruto, cores e texturas da casca. O DNA genomico foi extraido individualmente de cinco plantas de cada acesso. Foram analisados 40 locos de microssatelites. Destes, 34 amplificaram, identificando 100 alelos (variacao de um a cinco alelos por loco). Dos locos analisados 85,3% foram polimorficos, evidenciando a variabilidade genetica entre os acessos. A analise molecular da variância mostrou que 45,39% da variabilidade genetica e atribuida a variacao dentro dos acessos e 54,60% a diferencas entre acessos. Assim, apesar de haver variabilidade genetica dentro dos acessos, a maior proporcao da variabilidade em C. pepo encontra-se distribuida entre as diferentes variedades crioulas. A variacao dentro dos acessos e explicada pela alogamia da especie, pelo intercâmbio de sementes das variedades crioulas entre os agricultores e tambem pelos mesmos cultivarem mais de uma variedade de Cucurbita na mesma area.

Breeding for Fungus Resistance

Late blight, caused by the oomycete Phytophthora infestans, is a serious disease in potato and tomato crops throughout the world. It cuts yields by destroying leaves and rotting tubers during growth, development, and storage. Under favorable weather conditions, late blight is capable of destroying a potato crop in a matter of days. The development of potato varieties resistant and acceptable in the market could offer a number of advantages on the control of the disease. This chapter discusses breeding for resistance to P. infestans, but the majority of examples and strategies mentioned in relation to this pathogen can be applied to breeding for resistance to fungi in general. First, the aspects of plant physiological responses, pathogen-host interaction, vertical x horizontal resistance, co-evolution of the pathogen, and the host wild species are reviewed. Then, the germplasm and genetic variability, inheritance of resistance, trait relationships, stress induction and intensity, and duration of the disease, strategy and selection methods, and biotechnology applied to the breeding for fungus resistance are discussed. Also, considerations about the effects of the possible climate change on plant responses to the disease are made. Finally, closing remarks of the chapter are presented.