Agronomic Evaluation of 324 Intraspecific Hybrids of \u3cem\u3eBrachiaria decumbens\u3c/em\u3e in Brazil

Brachiaria decumbens cv. Basilisk is the most planted pasture grass in the tropics owing to its adaptation to poor and acid soils, typical of the tropics, plus good animal performance. This cultivar was responsible for a radical change of scenario in central Brazil in the early 1970s and is the only cultivar available commercially. Efforts to breed this species have been recent, as the successful somatic chromosome duplication of sexually reproducing diploid plants of B. decumbens was accomplished only in 2009 (Simioni and Valle 2009). Subsequently, intraspecific crosses with natural apomictic tetraploid accessions were carried out. Breeding is needed since cv. Basilisk is susceptible to grassland spittlebugs, which limit its widespread use. A recurrent selection scheme has been devised to improve the species and the first progeny are now under evaluation. This paper reports the preliminary results of the agronomic evaluation of 324 intraspecific hybrids of B. decumbens

Reciprocal Recurrent Selection in the Breeding of \u3cem\u3eBrachiaria decumbens\u3c/em\u3e

Pastures of Brachiaria decumbens cv. Basilisk radically changed the scenario of livestock production in central Brazil in the early 1970s and in fact, promoted the development of this vast region. However, despite the reasonable biomass yields and nutritional value when grown on these tropical acid soils, its susceptibility to grassland spittlebugs has limited its use. The breeding of B. decumbens in Brazil has been restricted to interspecific crosses using cv. Basilisk as a pollen donor due to the lack of compatible sexual ecotypes within this species. Recently, the successful chromosome duplication of a sexually reproducing diploid accession produced 3 successful events (Simioni and Valle 2009), enabling intraspecific crosses. This paper reports the onset of the research to obtain superior apomictic hybrids in B. decumbens using reciprocal recurrent selection (RRS), a cyclic breeding strategy

Agronomic and Nutritional Evaluation of Intraspecific Crosses in \u3cem\u3eBrachiaria decumbens\u3c/em\u3e

Brachiaria decumbens cv. Basilisk is the single most important forage grass used for pastures in the tropics. This cultivar has exceptional adaptation to acid soils, vigorous growth, ease of establishment, and good forage value throughout the year, but these favourable characteristics are counteracted by its susceptibility to insect pests such as spittlebug. Breeding to produce improved cultivars within this species was impossible until 2009 due to the lack of compatible sexual ecotypes. With the success of somatic chromosome duplication of sexually reproducing diploid plants of B. decumbens (Simioni and Valle 2009), intraspecific crosses with natural apomictic tetraploid accessions were finally possible. This paper reports the results of the agronomic and nutritional evaluation of 50 preselected intraspecific hybrids of B. decumbens

Effect of Season and Year of Evaluation in the Selection of \u3cem\u3eBrachiaria humidicola\u3c/em\u3e Hybrids

Brachiaria humidicola is well adapted to infertile and acid soils with poor drainage or temporary flooding (Keller-Grein et al. 1996). It is widely used in Brazil in wetlands and areas of marginal land characterised by waterlogged soils. During the evaluation stages of the breeding program of this species, genotypes are generally tested using consecutive cuts within different seasons for at least 2 years. The ‘Cerrado’ region, where most animal production takes place in Brazil, has 2 well defined seasons: spring-summer with warm weather and rain; and autumn-winter with cooler, dry weather. Thus, owing to environmental variation, especially related to climate, it is important to investigate the main effects of environmental factors (years and seasons), as well as interactions between genotypes and environmental factors in order to have greater confidence in the selection of superior hybrids of B. humidicola on the basis of agronomic and nutritional traits

Breeding Strategies for \u3cem\u3eBrachiaria\u3c/em\u3e spp. to Improve Productivity–An Ongoing Project

Two strategies have been used in the breeding of Brachiaria (syn. Urochloa) to produce new cultivars. The first involves exploring the natural variability existing in nature, which is the selection of ecotypes, mostly apomicts, from the diversity in germplasm banks. This strategy proved efficient originally and the cultivars in use in Brazil were derived in this way, but progress with this strategy is limited in the medium to long term

Obtenção de anticorpos policlonais contra proteínas presentes em plantas afetadas pela anomalia declínio dos citros Production of antibodies against proteins expressed in plants affected by citrus blight

O declínio dos citros, uma anomalia de etiologia desconhecida, continua sendo um dos entraves para o setor citrícola, uma vez que não existem medidas de prevenção e controle para as plantas acometidas pela anomalia. Para a caracterização e estudo da anomalia, muita ênfase tem sido dada à mudança na expressão gênica de plantas afetadas, que culmina no acúmulo de proteínas. Proteínas totais extraídas dos vasos do xilema de raízes de plantas afetadas pela anomalia, quando separadas por eletroforese no sistema SDS-PAGE 12,5%, apresentam um perfil eletroforético contendo proteínas com massas moleculares de cerca de 21, 23, 31 e 42 kDa, sendo que plantas consideradas sadias apresentam proteínas de 21, 31 e 42 kDa. Com este trabalho objetivou-se obter anticorpos contra essas proteínas, bem como a titulação adequada para os mesmos. Duas inoculações subcutâneas foram realizadas em coelhos, espaçadas de 15 dias, ambas usando cerca de 120 µg de proteína isolada, sendo que cada coelho recebeu uma proteína específica, visando à produção de anticorpos. A primeira sangria foi realizada aos 21 dias após a primeira inoculação e as demais semanalmente. A técnica Western Blotting foi realizada para a confirmação da especificidade dos anticorpos, bem como para determinação das respectivas titulações. O título 1:1500 foi aquele que proporcionou maior especificidade para as proteínas de 21, 23 e 31 kDa. Para a proteína de 42 kDa a melhor titulação foi de 1:3000. Estes anticorpos poderão ser utilizados em estudos para caracterização dessas proteínas.<br>Citrus blight, an abnormality of unknown etiology, is a major problem in citrus production, since there are no prevention and control measures to be taken. In order to characterize this abnormality, changes in genetic expression of the affected plants have exhaustedly been studied. Crude proteec extract obtained from the root xylem of the abnormal plants, when separated by SDS-PAGE 12,5%, display a profile with 21, 23, 31 and 42 kDa proteins. This work aimed the production of antibodies against those proteins, as well as their ideal dilution for use. Two subcutaneous inoculations were done in rabbits, within a 15-day interval, both with approximately 120mg of the isolated protein, with each rabbit receiving shots with a specific protein, for the production of the antibodies. A First bleeding was performed 21 days after the first inoculation and afterwards, weekly. Western blotting was carried out to confirm the presence of the antibodies and their respective dilutions. The 1:1500 dilution provided the best specificity for the 21, 23 and 31 kDa proteins, whereas for the 26 and 42 kDa proteins, the best dilution was at 1:3000