In situ and genetic characterization of Gossypium barbadense populations from the states of Pará and Amapá, Brazil

Abstract

-The objective of this work was to characterize the populations of Gossypium barbadense in the states of Amapá and Pará, Brazil. In situ characterization was conducted through interviews with the owners of the plants and environmental observations. Leaf or petal tissue as well as seed samples were collected for genetic characterization by single sequence repeats markers and for storage in germplasm banks, respectively. The plants were maintained in dooryards and used mainly for medical purposes. The genetic analysis showed no heterozygous plants at the loci tested (f = 1), indicating that reproduction occurs mainly through selfi ng. The total genetic diversity was high (H e = 0.39); and a high level of differentiation was observed between cotton plants from the two states (F ST = 0.36). Conventional methods of in situ maintenance of G. barbadense populations are not applicable. The conservation of the genetic variability of populations present in the two states could be achieved through germplasm collection and establishing of ex situ seed banks.Index term: cotton, genetic diversity, germplasm, SSR markers. Caracterização in situ e genética de Gossypium barbadense dos Estados do Pará e do AmapáResumo -O objetivo deste trabalho foi caracterizar populações de Gossypium barbadense dos estados do Amapá e Pará. A caracterização in situ foi conduzida por meio de entrevistas com os proprietários das plantas e por observações sobre o ambiente. Tecidos de folhas ou de pétalas, além de sementes, foram coletados para a caracterização genética com marcadores SSR ("single sequence repeats") e para o armazenamento em bancos de germoplasma, respectivamente. As plantas eram mantidas em fundos de quintal e usadas, principalmente, para fi ns medicinais. As análises genéticas não mostraram plantas heterozigotas nos locos testados (f = 1), o que indica que a reprodução ocorre principalmente por meio de autofecundação. A diversidade genética total foi alta (H e = 0,39), e um alto nível de diferenciação foi observado entre as plantas de algodoeiro dos dois estados (F ST = 0,36). Métodos convencionais para a manutenção in situ das populações de G. barbadense não são aplicáveis. A conservação da variabilidade genética das populações presentes nos dois estados deve ser realizada pela coleta de germoplasma e pela constituição de bancos de sementes ex situ.Termos para indexação: algodoeiro, diversidade genética, germoplasma, marcadores SSR.

Genetic characterization of cotton landraces found in the Paraíba and Rio Grande do Norte states

“…They have not been previously reported (Menezes et al 2010) and can be used in studies of differentiations of population and, as verified by Petit et al (1998), in the choice of preferred genotypes or populations for preservation. A similar number of exclusive alleles was observed in Gossypium barbadense (Almeida et al 2009), an ancestor species of mocó cotton grown in the Northeastern Brazil. Low oscillations in allelic frequencies were observed between the two states.…”

“…As demonstrated in other works on genetic diversity of cotton population, the use of SSR markers has helped to design conservation strategies (Almeida et al 2009. The high diversity rate inside states and low genetic difference between them has showed that the conservation de cotton plants was given priority in one state in detriment of other.…”

“…Despite the maintenance of ex situ collections, an increased loss of diversity occurs in situ, caused by changes to economical and cultural habits (Almeida et al 2009, Menezes et al 2010, and preservation strategies must be constantly renewed. The knowledge of genetic diversity and structure may nowadays be applied both as a resource to improve genetic diversity of breeding populations and to establish conservation measures for in situ and ex situ preservation (Negri andTiranti 2010, Carvalho et al 2014).…”

“…Microsatellite or Simple Sequence Repeat (SSR) markers have been widely used to obtain genetic maps (Zhang et al 2014), genetic characterization of germplasm (Bertini et al 2005, Almeida et al 2009), genetic of nature populations (Alves et al 2013), detect gene flow (Dantas et al 2012), correlation between traits performance and SSR markers (Zhen et al 2009, Xiao et al 2010). …”

Biodiversity Measures in Agriculture Using DNA

“…For example, the traditional cotton Gossypium barbadense, which used to be cultivated by native South American inhabitants, was classified in different subspecies when the seed from the same boll were adhered to each other, forming the called kidney seeds. This trait is, presumably, controlled by a single locus (Almeida et al, 2009), but for some authors this single trait is not relevant enough to differentiate subspecies, and molecular markers could be used to explain this process. Population genetics has been markedly based on studies using neutral molecular markers, and the obtained genetic structure provides information individuals in a population are more related among themselves than with individuals of other populations.…”