Programa de Pós-graduação em Agronomia
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Navegando Programa de Pós-graduação em Agronomia por Por Orientador "BRONDANI, Claudio"
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Item Caracterização agronômica e molecular da coleção nuclear de arroz da Embrapa(Universidade Federal de Goiás, 2010-08-31) BUENO, Luíce Gomes; OLIVEIRA, Jaison Pereira de; http://lattes.cnpq.br/7342298421214478; BRONDANI, Claudio; http://lattes.cnpq.br/4775600104554147The plant genetic resources stored ex situ are considered as a genetic repository, and are raw material for the development of the world agriculture. In rice, despite its high genetic variability, the lack of information of accessions to compose a databank prevents its use to help the choice of genitors for the breeding programs. The Embrapa Rice Core Collection (ERiCC) was developed from 10,000 accessions from Embrapa GeneBank, and it was set up by 550 accessions, divided in three subsets: 1) 94 lines and cultivars from Brazil (LCB); 2) 148 lines and cultivars from abroad (LCI); and 3) 308 traditional varieties (VT), obtained from germplasm collection expeditions in Brazil. This work aimed: 1) to evaluate the extension of genetic variability of 550 accessions from ERiCC by means of agronomic traits characterization using mixed models and multivariate statistics; 2) to perform a comparative analysis of the genetic divergence considering the agronomical and SSR markers characterizations; and 3) to identify the genotypes with higher genetic diversity and with the best agronomic performances, aiming to promote the most efficient use of such germplasm in breeding programs. The agronomic characterization of 550 accessions was performed in nine field experiments, evaluating 18 phenological-agronomic traits. The data were analyzed using the mixed linear and AMMI models. There was wide variation range of genotypical values for most evaluated traits. In different environments, it was observed VT accessions among the high-yielding materials, demonstrating the potential of this group of germplasm, particularly important due to its high genetic variability, to contribute to the development of cultivars regionally adapted. The AMMI approach allowed a good discrimination of ERiCC rice genotypes in relation to the adaptive performance, identifying the accessions CA880078, CA990001, CA870071 (subset VT), and CNA0009113 (LCI) as having good yield and broad adaptation to distinct environments. The comparative analysis of genetic diversity between agronomic and molecular data was performed using the 242 lines and cultivars accessions from ERiCC, which were characterized by 86 fluorescent SSR markers, and five agronomic traits with genotypic values predicted (values without from the effects of interaction genotypes x environment, from a joint analysis of nine experiments. The genetic divergence among accessions was estimated by the average Euclidian distance for phenotypical data, and by the Rogers modified by Wright (RW) genetic distance. The datasets were jointly analyzed by descriptive and multivariate statistics, using correlation analyses from hierarchical grouping of Ward and UPGMA methods. The phenotypical and molecular data showed a broad distribution of dissimilarity indexes, despite they showed different patterns of variation between them. Low molecular distances were associated to low phenotypical distances, however to high molecular distances, occurred a high broad range of phenotypical variation. The correlation between genetical and phenotypical dissimilarities was significant for both lowland and upland accessions, despite with different values (r=0.156 and r=0.409, respectively). Due to the low relation between phenotypical and molecular data, the analysis of genotypes to be used in breeding programs must include both evaluations to a better accession characterization. Considering the high yielding accessions, the higher molecular distances were identified among the accessions from lowland system of cultivation, among which BR IRGA 413 and CNA0005014, BR IRGA 413 and CNA0005853, and CNA0004552 and CNA0005014. Considering the upland accessions, maximum genetic distances were identified in CNA0000482 and CNA0006422, CNA0001006 and CNA0006422, and CNA0001006 and CNA0003490. The molecular analysis was able to identify accessions with reduced genetic relationship, that if used as genitors, will result in a progeny with a high probability to find new allelic combinations. On the other hand, the phenotypical characterization is important to identify accessions not just genetically divergent, but with superior agronomic trait performances for breeding programs. The results of this work will permit to increase the activities related to the characterization of accessions from rice Genebank, giving support of breeding programs to choose the best accessions to obtain new cultivars, with favorable traits, and broad genetic basis. In addition, a continuous program of phenotypical and molecular characterization of germplasm will be able to identify accessions to increase the genetic variability of ERiCC.Item Determinação da variabilidade genética nas populações de seleção recorrente de arroz CNA-IRAT 4 e CNA 12 utilizando marcadores microssatélites(Universidade Federal de Goiás, 2008-03-07) PINHEIRO, Letícia da Silveira; BRONDANI, Claudio; http://lattes.cnpq.br/4775600104554147Recurrent Selection is a population inbreed method that is not traditionally used in autogamous species as rice. However, it is still an interesting methodology to the implementation of recurrent selection populations, due to the possibility of obtaining genotypes with wide genetic base and adequate agronomical traits. It is even more attractive when a great genetic variability is easily available, as it is for rice and could be largely used in the development of more productive elite cultivars and with a better production stability even under low input agricultural systems. Two recurrent selection irrigated rice populations, developed by Embrapa Arroz e Feijão, were synthetized using different recombination methods. The CNA-IRAT 4 population was developed in field conditions using male-sterelity, while the CNA 12 population originated from manual crosses in a circulant partial diallel scheme. The aim of this work was the evaluation of the genetic variability among cycles of the two recurrent selection populations using fourteen SSR markers. Hundred and eighty genotypes of the cycles 1, 2 and 5 of CNA-IRAT 4 population and cycles 1 and 2 of CNA 12, were evaluated. The AMOVA did not indicate any genetic structure among the cycles of selection, meaning that the greater variation was attributed between individuals within cycles, in both studied populations. Unexpected alleles, which means alleles that not belong to the genetic pool of the genitors, were identified in both populations and in all cycles evaluated, mostly of these alleles were observed on CNA-IRAT 4 population. These alleles were probably a result of undesired crosses of genotypes which did not belong to both populations. Parameters Fis and Fit of Wright s statistics indicated that the genetic variability of the manually conducted population (CNA 12) were increased while the population using male-sterelity recombination (CNA-IRAT 4) were reduced. The mean reason for this particular situation was due to the directionally crosses that promoted a greater combination between the alleles of all genitors, while male-sterelity methodology pollination the alleles from plants with major height and more capable of producing more pollen were privileged. To avoid the genetic drift in CNA-IRAT 4, genotypes genetically divergent, with more General Capacity of Combination and with good agronomic attributes, should be introduced on this population.