Genetic diversity of Gossypium barbadense from the central Brazilian Amazon

The Amazon Basin is a center of diversity of Gossypium barbadense and the strategy for conservation of this genetic resource depends on the knowledge of the diversity maintained in Amazonas State. During two expeditions, in 2012 and 2014, plants were collected in ten municipalities in the state of Amazonas, in the central Brazilian Amazon region. The molecular diversity was estimated by SSR markers for 50 samples collected in 2012. The morphological diversity of 24 plants collected in 2014 was assessed ex situ and compared to that of 50 plants of the same and other cotton varieties from other Brazilian states. Most of plants evaluated in situ in Amazonas had purple petioles and veins (82%), associated to medicinal use, and kidney seeds (78%). The ex situ morphological analysies showed that G. barbadense plants from the Amazonas state: i) presented higher similarity to cotton plants from other northern Brazilian states, and ii) were grouped separately from those of other northern Brazilian states by descriptor analysis. Both the molecular (H=0.41) and morphological (H=0.38 +/- 0.02) diversity among the collected plants was considered intermediary. Our study indicates the distinctiveness of Amazon cottons, and contributes to demonstrate the discrimination power of multicategorical traits.