Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

Fontes orgânicas e inorgânicas de zinco e cobre como melhoradores de desempenho em leitões desmamados Organic and inorganic source of zinc and cooper as growth promoters for weanling piglets

Foram conduzidos dois experimentos para avaliar fontes orgânicas e inorgânicas de zinco e cobre nas dietas e seus efeitos no desempenho de leitões desmamados aos 21 dias de idade. Em cada experimento, foram utilizados 90 leitões em delineamento experimental de blocos ao acaso, com cinco dietas, seis repetições e três animais por parcela. As dietas utilizadas nos experimentos 1 e 2 continham 120 ppm de zinco e 10 ppm de cobre na forma de sulfato. No experimento 1, foram suplementadas com 0, 300, 600 e 900 ppm de zinco na forma orgânica ou 2.400 ppm na forma de óxido (ZnO) e, no experimento 2, com 0, 50, 100 e 150 ppm de cobre na forma orgânica ou 240 ppm de cobre na forma de sulfato (CuSO4 H2O). No experimento 1, os níveis de zinco de fonte orgânica tiveram efeito linear no consumo de ração e no ganho de peso nos períodos de 0 a 15 dias e de 0 a 21 dias pós-desmame. O ganho de peso nas fases de 0 a 35 dias e de 0 a 42 dias pós-desmame e o consumo de ração dos leitões que receberam a dieta com 900 ppm de zinco de fonte orgânica não diferiram dos valores observados naqueles que receberam a dieta com 2.400 ppm de zinco na forma inorgânica. A suplementação da dieta com zinco na forma orgânica (900 ppm) ou inorgânica (2.400 ppm) aumentou o consumo de ração e o ganho de peso de leitões nas primeiras três semanas após o desmame. A suplementação da dieta com 2.400 ppm de zinco na forma inorgânica reduziu a incidência de diarreia nas primeiras três semanas pós-desmame. No experimento 2, os níveis de cobre de fonte orgânica tiveram efeito quadrático no consumo de ração dos leitões nos períodos de 0 a 31 e de 0 a 40 dias pós-desmame. A suplementação da dieta com cobre, tanto de fonte orgânica (90 ppm) como inorgânica (240 ppm), aumenta o consumo de ração e o ganho de peso de leitões nos primeiros 40 dias pós-desmame.<br>Two experiments were conducted to evaluate organic and inorganic sources of zinc and copper and their effects on performance of piglets weaned at 21 days of age. In each experiment, it was used 90 piglets in a randomized block experimental design with five diets and six replications and three animals per plot. The diets used in experiments 1 and 2 contained 120 ppm zinc and 10 ppm copper as sulfate. The diets of experiment 1 were supplemented with 0, 300, 600 or 900 ppm of zinc in organic form or 2,400 ppm as zinc oxide (ZnO) and in the experiment 2, the diets were supplemented with 0, 50, 100 and 150 ppm copper in organic form or 240 ppm copper as sulphate (CuSO4H2O). In the experiment 1, levels of zinc from the organic source linearly affected on feed intake and weight gain from 0 to 15 days and from 0 to 21 days post weaning. Weight gain in the 0 to 35 day phase and from 0 to 42 days post-weaning and feed intake of the piglets fed diet with 900 ppm zinc from organic source were not different from the values observed on those fed diet 2,400 ppm of zinc from the inorganic form. Supplementation of diet with zinc in the organic form (900 ppm) or inorganic form (2,400 ppm) increased feed intake and weight gain of piglets in the first three weeks after weaning. Supplementation of diet with 2,400 ppm of zinc in the inorganic form reduced the occurrence of diarrhea in the first three weeks post-weaning. In experiment 2, levels of copper from organic source had a quadratic effect on feed intake of piglets in the periods from 0 to 31 and from 0 to 40 days post-weaning. The supplementation of diet with copper in organic form (90 ppm) or inorganic form (240 ppm) increases feed intake and weight gain of piglets on the first 40 days post-weaning