Validation and valorization of maize core collection, subgroup flint endosperm / ValidaÃÃo e valoraÃÃo da coleÃÃo nÃcleo de milho, subgrupo endosperma duro.

AUTOR(ES)

DÃa AlÃcia Martins Netto

DATA DE PUBLICAÇÃO

2003

RESUMO

The utilization efficiency of a maize core collection can be incremented by using molecular and morpho-agronomical characteristics, providing more detailed descriptions about these accessions. The objectives of this work were to validate and valorize maize core collection, sub-group flint endosperm of the Brazilian Agricultural Research Corporation (Embrapa), through the use of morphoagronomical descriptors and AFLP molecular markers. Fifty eight accessions from the core collection and a sample of 21 accessions of the whole collection were used. Twenty two morpho-agronomical descriptors and six AFLP primers combinations were tested to obtain the genetic patterns. Although morphoagronomical data of the whole collection sample had been obtained from different years and locals, through data base consulting, comparative tests were made between the two collections. There were significant differences for means, variances, and frequency distribution of the accessions in the two collections in relation to the majority of descriptors. The core collection validation study using morpho-agronomical data was not conclusive due the existence of genotypeenvironment interaction. Dendrograms of core collection and whole collection sample showed similar general structure, indicating a good fit among the cophenetic and genetic distance matrices. The genetic diversity of whole collection sample and core collection, based on AFLP markers, was 94,45% attributed to the diversity existing inside the collections and only 5,55% to the difference between the collections. Neiâs genetic identity was high, showing similar allelic frequencies between collections. The allelic frequency distribution did not present any significant difference for 79% of loci. The analysis of molecular variance did not show significant difference of genetic variability between the core collection and whole collection sample. Molecular characterization of accessions allowed to verify that the stratified sampling strategy using ecogeographic regions in the development of the maize core collection, subgroup flint, was adequate, indicating that the core collection genetic variability is representative of the whole collection.

ASSUNTO(S)

melhoramento genÃtico vegetal marcador molecular aflp plant breeding germoplasm agronomical characteristics milho molecular markers caracterÃstica agronÃmica maize aflp melhoramento vegetal germoplasma

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