SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Santos,Mateus Figueiredo; Moro,Gustavo Vitti; Aguiar,Aurélio Mendes; Souza Jr.,Cláudio Lopes de.

This paper reports the effects of three cycles of reciprocal recurrent selection (RRS) on the means, genetic variances, and on the genetic correlations for several traits in the IG-1 and IG-2 maize (Zea mays L.) populations. Interpopulation full-sib progenies from cycle zero (C0) and from cycle 3 (C3) of RRS were evaluated in two locations. RRS was highly effective to improve the traits according the objectives of the program: grain yield and prolificacy increased significantly, while plant height, ear height, and ear placement decreased significantly. Genetic variances for all traits decreased significantly from C0 to C3, but the genetic correlations did not change consistently across the cycles of selection. The expected responses to the fourth cycle of...

Microsatellite-assisted backcross selection in maize

Palavras-chave: Maize; Responses to selection; Genetic variances; Genetic correlations.

Ano: 2005

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572005000500021

Benchimol,Luciana Lasry; Souza Jr.,Cláudio Lopes de; Souza,Anete Pereira de.

A microsatellite marker (SSR) was chosen to simulate a target allele and three criteria (02, 04 and 06 markers per chromosome) were tested to evaluate the most efficient parameters for performing marker-assisted backcross (MAB) selection. We used 53 polymorphic SSRs to genotype 186 BC1 maize (Zea mays L.) plants produced by crossing the inbred maize lines L-08-05 (donor parent) and L-14-4B (recurrent parent). The second backcross (BC2) generation was produced with 180 plants and screened with markers which were not recovered from the first backcross (BC1) generation. A total of 480 plants were evaluated in the third backcross (BC3) generation from which 48 plants were selected for parental genotype recovery. Recurrent genotype recovery averages in three...

Response to recurrent selection under small effective population size

Palavras-chave: Maize; Marker-assisted backcrossing (MAB); Marker-assisted selection; Microsatellites.

Ano: 2005

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572005000500022

Souza Jr.,Cláudio Lopes de; Geraldi,Isaias Olívio; Vencovsky,Roland.

A formula was derived for the prediction of the response to recurrent selection when the effective population size (Ne) is small. Usually, responses to selection have been estimated by Rs = icsigma²A/sigmaPh, where i, c, sigma²A, and sigmaPh stand for standardized selection differential, parental control, additive variance, and phenotypic standard deviation, respectively. This expression, however, was derived under the assumption of infinite population size. By introducing the effects of finite population size, the expression derived was Rs = [ic(sigma²A + deltaFD1)/sigmaPh] - DFID, where deltaF, ID and D1 are the changes in the inbreeding coefficient, the inbreeding depression, and the covariance of additive and homozygous dominance effects, respectively....

Genetic effects for maize traits in acid and non-acid soils

Ano: 2000

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572000000400023

Pérez Velásquez,Juan C.; Souza Jr.,Cláudio Lopes de; Narro,Luis A.; Pandey,Shivaji; De León,Carlos.

Breeding programs for acid-soil tolerance are desirable as a relatively inexpensive and permanent way for increasing maize (Zea mays L.) yield on these soils. Our objective was to compare the genetic effects controlling the expression of maize traits in acid and non-acid soils. Seven related and one unrelated inbred lines, with different levels of tolerance to acid soil, and their F1, F2, BC1, and BC2 generations were evaluated in four acid and two non-acid soils. Estimates of additive, dominance, and epistatic effects were computed for grain yield, plant height, days to mid-silk, and prolificacy, using the generation means analysis procedure. For all traits the major part of the variation was accounted for by additive and dominance effects, with dominance...

Comparison of similarity coefficients used for cluster analysis with dominant markers in maize (Zea mays L)

Palavras-chave: Acid soils; Additive; Dominant; Epistatic effects; Generation analysis.

Ano: 2008

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572008000100017

Meyer,Andréia da Silva; Garcia,Antonio Augusto Franco; Souza,Anete Pereira de; Souza Jr.,Cláudio Lopes de.

The objective of this study was to evaluate whether different similarity coefficients used with dominant markers can influence the results of cluster analysis, using eighteen inbred lines of maize from two different populations, BR-105 and BR-106. These were analyzed by AFLP and RAPD markers and eight similarity coefficients were calculated: Jaccard, Sorensen-Dice, Anderberg, Ochiai, Simple-matching, Rogers and Tanimoto, Ochiai II and Russel and Rao. The similarity matrices obtained were compared by the Spearman correlation, cluster analysis with dendrograms (UPGMA, WPGMA, Single Linkage, Complete Linkage and Neighbour-Joining methods), the consensus fork index between all pairs of dendrograms, groups obtained through the Tocher optimization procedure and...

Microsatellite-dense genetic map: towards genome coverage in a tropical maize (Zea mays L.) population

Palavras-chave: Genetic divergence; Heterotic groups; AFLP; RAPD; Multivariate analysis.

Ano: 2004

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572004000100014

Rev. Bras. Bot.

Lima,Milena De Luna Alves; Souza Jr.,Cláudio Lopes de; Souza,Anete Pareira de.

Dense molecular genetic maps are used for an efficient quantitative trait loci (QTL) mapping and in the marker-assisted selection programs. A dense genetic map was generated with 139 microsatellite markers using 256 F2 plants generated by the crossing of two tropical maize inbred lines (L-02-03D and L-20-01F). This map presented 1,858.61 cM in length, where 10 linkage groups were found spanned, with an average interval of 13.47 cM between adjacent markers. Seventy seven percent of the maize genetic mapping bins were covered, which means an increase of 14% coverage in relation to the previous tropical maize maps. The results provide a more detailed and informative genetic map in a tropical maize population representing the first step to make possible the...

Phenotypic recurrent selection to improve protein quality in non-opaque maize populations

Palavras-chave: Dense genetic map; Genome coverage; Microsatellites; Tropical maize; Zea mays L..

Ano: 2009

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-84042009000300009

Garcia,Antonio Augusto Franco; Souza Jr.,Cláudio Lopes de.

Maize (Zea mays L.) protein is considered to be of low quality due to low levels of the essential lysine and tryptophan amino acids. An alternative to solve this problem is to use the opaque-2 gene, which improves the level of these amino acids, but has negative pleiotropic effects on agronomic characters. A phenotypic recurrent selection scheme was carried out in two non-opaque maize populations to verify the possibility of improving their protein quality without using this gene. Four cycles were completed and a 20% selection intensity for tryptophan content in the kernels was used in two populations, IG-1 and IG-2. The original and the four-cycle populations were evaluated in three locations for agronomic traits. For protein and tryptophan content, a...

Combining ability of inbred lines of maize and stability of their respective single-crosses

Palavras-chave: Tryptophan; Correlated response; Maize breeding.

Ano: 2002

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162002000400018

Aguiar,Aurélio Mendes; Carlini-Garcia,Luciana Aparecida; Silva,Adelmo Resende da; Santos,Mateus Figueiredo; Garcia,Antonio Augusto Franco; Souza Jr.,Cláudio Lopes de.

The utilization of diallel crosses for identification of superior combinations is a common practice in maize (Zea mays L.) breeding programs. This methodology allows the estimation of the combining ability of genotypes being evaluated. In this work, five inbred lines were evaluated as to their general (GCA) and specific (SCA) combining abilities, by using a complete diallel scheme. The single-crosses produced between these inbred lines were evaluated in seven environments, along with two checks, by using a randomized complete block design. Traits analized were: grain yield, plant height, ear height, ear placement, and prolificacy. A diallel analysis was carried out, following an adaptation of Griffing's method IV, in addition to hybrid stability and...

Alocação de linhagens de milho derivadas das populações BR-105 e BR-106 em grupos heteróticos

Palavras-chave: Diallel crosses; Genotype vs. environment interaction; Grain yield; Adaptability.

Ano: 2003

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162003000100013

Pinto,Rogério de Melo Costa; Garcia,Antonio Augusto Franco; Souza Jr.,Cláudio Lopes de.

Os grupos heteróticos são importantes no melhoramento de milho, pois permitem o uso mais eficiente do germoplasma. Assim, o objetivo deste trabalho foi alocar linhagens de milho em grupos heteróticos a partir de estimativas da capacidade específica de combinação. Oito linhagens S3 da população BR-105 e dez da BR-106, foram cruzadas ao nível interpopulacional seguindo um sistema dialélico. Oitenta híbridos simples foram obtidos e avaliados em látices em três ambientes. Foram avaliados os caracteres produção de grãos (PG), altura da planta (AP) e altura da espiga (AE). As estimativas das capacidades geral (CGC) e específica (CEC) de combinação foram obtidas segundo o método 4, modelo I de Griffing. A partir das estimativas de CEC, as linhagens foram alocadas...

Performance of maize single-crosses developed from populations improved by a modified reciprocal recurrent selection

Palavras-chave: Zea mays; Cruzamento dialélico; Capacidade de combinação.

Ano: 2001

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162001000300016

Souza Jr.,Cláudio Lopes de; Barrios,Sanzio Carvalho Lima; Moro,Gustavo Vitti.

Maize (Zea mays L.) elite inbred lines developed from pedigree programs tend to be genetically related. Therefore, it is necessary to incorporate unrelated inbreds to those programs to allow the continued release of outstanding single-crosses. The objectives of this research were to compare the usefulness of a modified reciprocal recurrent selection procedure (MRRS) to improve populations to be used as sources of elite inbreds and outstanding single-crosses to integrate pedigree programs, and to investigate the effects of selection on the relative contribution of general (GCA) and specific combining (SCA) abilities to the single-crosses variation. Eight and six S3 lines from populations IG-3-C1 and IG-4-C1, respectively, selected from the first cycle of...

Isoenzymatic variability in tropical maize populations under reciprocal recurrent selection

Palavras-chave: Diallel design; Maize improvement; Combining ability.

Ano: 2010

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162010000200011

Pinto,Luciana Rossini; Vieira,Maria Lúcia Carneiro; Souza Jr.,Cláudio Lopes de; Silva,Rainério Meireles da.

Maize (Zea mays L.) is one of the crops in which the genetic variability has been extensively studied at isoenzymatic loci. The genetic variability of the maize populations BR-105 and BR-106, and the synthetics IG-3 and IG-4, obtained after one cycle of a high-intensity reciprocal recurrent selection (RRS), was investigated at seven isoenzymatic loci. A total of twenty alleles were identified, and most of the private alleles were found in the BR-106 population. One cycle of reciprocal recurrent selection (RRS) caused reductions of 12% in the number of alleles in both populations. Changes in allele frequencies were also observed between populations and synthetics, mainly for the Est 2 locus. Populations presented similar values for the number of alleles per...