Genetic diversity is essential for crop breeding and one way to estimate it is through the concept of genetic base, which can be defined as the number of ancestors and their relative genetic contributions (RGC) to each cultivar. indicated that there has been an increase in the number of ancestors over time, but the four main ancestors were the same over all periods, and their cumulative RGC increased from 46.6% to 57.6%, indicating a narrowing of the genetic base. Bragg, Davis, and Lee. With the growing importance of soybean, breeders began crossing these cultivars among themselves and with other sources, obtaining the first Brazilian cultivars, such as Industrial, Santa Rosa and Campos Gerais. The frequent crossing of a small number of cultivars can lead to a reduction in genetic diversity. One way to measure the genetic diversity of a crop is usually through the concept of genetic base, which can be defined as the number of ancestors and their relative genetic contribution (RGC) to a specific group (Cui is the COP between two cultivars X and Y; A and B are the parents of cultivar X and C and D are parents of cultivar Y. We started by assembling the complete pedigrees of the Brazilian soybean cultivars, and traced them back to the ancestors, estimating the probability of the contribution that each ancestor made to each cultivar, that is, the COP between an ancestor and a cultivar. The following assumptions were made: (i) all the ancestors are impartial, in other words, the COP between pairs of Rabbit Polyclonal to HMGB1 ancestors Glycitein is usually = 0; (ii) in a cross, each parent contributes 50% of the genes; (iii) the cultivars, ancestors, and lines are all homozygous and homogenous; (iv) the COP between a herb selection and its antecedent was considered to be = 1; (v) the COP between a mutant and the original genotype was considered to be = 1. Glycitein The calculations were performed using the computer software Microsoft Excel? (2003). The relative genetic contribution (RGC) of different ancestors to a given selection was calculated by partitioning the genetic constitution of each cultivar, using the COP as an estimate. The mean RGC of the ancestors was calculated by averaging the RGC of that ancestor from all cultivars. The accumulated genetic contribution (AGC) is the sum, in decreasing order of importance, of the ancestral RGCs. The presence of an ancestor in a pedigree was decided as its frequency. The mean number of ancestors was determined by averaging the number of ancestors each cultivar had. The ancestor/cultivar ratio was also decided. The cultivars were subdivided into groups according to the 12 months of release or 12 months of registration (when available) in Brazil. The timeframe was divided into five periods: before 1971, 1971C1980, 1981C1990, 1991C2000 and 2001C2009. The cultivars were also subdivided according to origin: public or private. The few cultivars that were developed abroad were excluded from this analysis. For each subgroup, all the above mentioned parameters were also calculated. Results and Discussion Pedigrees Although over 700 cultivars were officially registered in Brazil in 2010 2010, according to CultivarWeb, the database for the National Cultivar Registry from the Ministry of Agriculture, Livestock and Food Supply, we were only able to obtain the pedigrees for 444 cultivars. Due to the Variety Protection Act of 1997, many breeders have not made public the pedigrees of released cultivars, especially more recent ones. A few pedigrees deserve special attention. First, the cultivar FT-Cristalina originated from a natural cross between UFV-1 and an unknown parent. But based on morphological data, some breeders suggest that the unknown parent was Davis (Hiromoto and Vello, 1986), so this pedigree was used in the Glycitein present work. The same authors reported that cultivar BR-9 (Savana) originated from the bulk LoB 74-2, with a probable pedigree being Davis x (Hill x PI 240664). Another important observation made is usually that morphological and molecular marker data have not backed the pedigree from the cultivar Lincoln (Gizlice (1994), for testing options because of the lacking ancestor. For the very best 20 ancestors, just two are unavailable (PI 60406 and Mogiana). Normally, there have been 10.52 ancestors for every cultivar, which range from 2 to 23. Nevertheless, this increase should be used with caution, because it is because of the incorporation of low-contribution ancestors mainly. For instance, the mean quantity.