Escolha de descritores mínimos e estabelecimento de coleções nucleares em Capsicum spp.
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Data
2008-03-05
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Universidade Federal de Goiás
Resumo
The plant genetic diversity is a valuable guarantee for possible adversities that
can be risking the survival of biological species. Brazil is one of the richest countries in
biodiversity of plants, with about 20% of all the existing biodiversity on Earth and around
19% of the agricultural lands in the world. Genetic resources are studied in well-defined
stages, such as collecting or introduction, multiplication, preservation/conservation,
evaluation/characterization and use. In Brazil, the Empresa Brasileira de Pesquisa
Agropecuária manages a national system of curatorship of genetic resources in which more
than 250 thousand samples of plants, animals and microorganisms are preserved. The
plants of the genus Capsicum (chilli and sweet peppers) are found throughout the national
territory, presenting countless kinds, with a great phenotypic and genotypic diversity.
Practically all the brazilian states have their own cultivars, but some of them, can be in
fact, considered a mere duplicate because, sometimes, the same cultivar is known under
different names. Thus, the morphological characterization is a task of great importance to
this plant genus so, it is possible to avoid the conservation and maintenance of accessions
of similar genomic patterns in germplasm banks. Embrapa Hortaliças has a collection of
germplasm of sweet and chilli peppers (Capsicum spp.), which amounts to about 2,500
accessions. These mainly belong to the species C. annuum, C. baccatum, C. chinense and
C. frutescens. The morphological characterization of most of these acessions (893) have
been carried out in recent years for a series of characters (descriptors) which allow the
investigation of the structure of their genetic variability and, from then the proposition of
strategies to handle the collection. Considering the need of studies aiming to know, value
and use the accessions of the Capsicum spp. Embrapa Hortaliças collection, this research
was developed with the objective of describing the accessions and the descriptors available
in this collection, in order to search for minimum descriptors and propose core collections
for this germplasm bank. The study demonstrated that it is possible to reduce around 50%
the number of descriptors currently used in the characterization of the accessions, without
significant harm to the representation of the genetic variability of the collection. The
factorial correspondence analysis showed to be appropriate for the selection of minimum
descriptors, as well as to the proposition of core collections from germplasm banks,
characterized, predominantly, by qualitative data. Variables related to the fruit showed
great variability in all the germplasm collection, demonstrating that these attributes are
important in the genetic discrimination among the accessions. The study also showed that
the geographical origin, regardless of the species, is directly associated with the genetic
divergence among the accessions in Capsicum spp.
Descrição
Citação
SILVA, Waldir Camargos Júnior e. Choice of minimum descriptors and establishment of Capsicum spp.
core collections. 2008. 140 f. Tese (Doutorado em Ciências Agrárias) - Universidade Federal de Goiás, Goiânia, 2008.