Genetic studies of a male-sterile, female-fertile soybean mutant.

Studies on a new spontaneous male-sterile / female-fertile soybean mutant identified by the Embrapa Soybean breeding program were carried out in Londrina, PR. The mutant showing segregation for male-sterility (BR93-12879) was selected within F4 progeny lines derived from the IAS-5 (3) X OCEPAR 9-SS1 cross performed in 1993. The F1 , F2 and F3 generations of cross among heterozygous plants of the BR93-12879 line and recessive homozygous plants (male-sterile) of the T 266H (ms1ms1), T 259H (ms2ms2 ), T 273H (ms3ms3), T274H (ms4ms4), T 277H (ms5ms5) and T 295H (ms6ms6) lines were studied to identify whether the new mutationis conditioned by a new allele or by a mutation in one of the six loci already described in the literature. The F1, F2 and F3 plants from the crosses were visually classified as male-sterile or male-fertile. Results from the allele test and inheritance study among the mutant genotype and the recessive homozygous male-sterile lines (ms1, ms2, ms3, ms4, ms5 and ms6 ) showed that a single recessive gene controls the male-sterile trait of BR93-12879. This gene is allele to the already described ms1 -gene and resulted from a genetic mutation in the ms-loci

Cultivar de soja BRS Aroeira.

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Características agronômicas e morfológicas das cultivares de soja desenvolvidas para as regiões de baixas latitudes.

Disponível via Word Wide Web. http: www.cpatsa.embrapa.b

MA/BR 65 (Sambaiba): nova cultivar de soja adaptada para o Estado do Piaui.

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Photoperiodism and genetic control of the long juvenile period in soybean: a review.

Soybean (Glycine max (L.) Merrill)is a short day plant that flowers when days are shorter than the maximum critical value, and this period is specific for each genotype. Soybean sensitivity to photoperiodism determines the limits of the sowing period for a latitude and hinders adaptation to wider ranges of latitude. The long juvenile period (LJP), which delays flowering under short day condictions, has been identified in soybean cultivars. The introduction of the LJP characteristic in soybean has made its cultivation possible in regions with latitudes lower than 15 o . Knowledge of the controlling genetic mechanisms of this characteristic can help in the development of soybean genotypes for lower latitudes with greater adaptation to sowing periods within the same latitude. Some conclusions about the genetic LJP control in soybean were reached from the present review: a) plants with LJP have a lower development rate for flowering, resulting in the lengthening of the vegetative period; b) the LJP characteristic has a direct influence on plant photoreceptivity and flowering induction; c) the genetic control of flowering time in short days is determined by a different and independent genetic system from that which determines long day flowering time; d) late flowering under short day conditions is a quantitative characteristic controlled by recessive genes, and it is believed that one to five main genes control flowering. Genotypes with a single pair of recessive alleles did not have LJP

Melhoramento da soja para regiões de baixas latitudes.

Disponível via Word Wide Web. http: www.cpatsa.embrapa.br

Molecular markers linked to the resistance to race 3 of the soybean cyst nematode Heterodera glycines.

The objective of this study was to identify molecular markers associated with the resistance to race 3 of the SCN. Two Microsatellites (Satt187 and Satt309) and three RAPD markers (OPAG-05 946, OPF-04 1038 , and OPAQ-01 1987 ) were found which explained 31.3%, 28.9%, 13.8%, 11.4% and 9.9%, respectively, of the phenotypic resistance variation to race 3 of the SCN. However, by multiple regression analysis, with the elimination of markers which least contributed to an explanation of the resistance, the most significant combination occurred with the inclusion of the markers Satt187 and Satt309, which together explained 75.2% of the resistance. These markers were mapped in two distinct regions. One located in the linkage group G with the markers OPAG-05 846, OPF-04 1038 , OPAQ-01 1987 and Satt309 at an interval of 34.7 cM, and another located in the group A 2 with the marker Satt187. Inheritance studies have shown those two dominant genes control resistance to SCN, in the population analyzed

MA/BR 64 (Parnaiba): nova cultivar de soja adaptada para os cerrados do Meio-Norte do Brasil.

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BRS MA Babacu: cultivar de soja de ciclo tardio e resistente ao cancro da haste.

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