MOLECULAR CYTOGENETIC CHARACTERIZATION OF THE NATIVE FORAGE GRASS TRICHLORIS CRINITA

FLORENCIA GALDEANO; PATRICIA ELDA NOVO; FRANCISCO ESPINOZA; CARRIZO, JULIO MARTIN; CAMILO LUIS QUARIN

Foz do Iguaçu

Congreso; XXII International Congress of Genetics; 2018

Brazilian Genetics Society (SBG), Latin American Association of Genetics (ALAG), International Genetics Federation (IGF)

The Southamerican grass, Paspalum chaseanum, is a multiploid species with a sexual self-incompatible diploid (2n=2x=20) cytotype and a tetraploid (2n=4x=40) cytotype which reproduces by apomixis, speudogamy and self-compatibility. Sexual plants have never been found in the tetraploid cytotype. The induction of autoploidy from diploid seedlings was aimed at obtaining sexual tetraploid plants that can be used as female parents in crosses with plants of the tetraploid cytotype, or other apomictic, tetraploid, close related congeneric species. A total of 230 diploid seedlings were soaked in a solution of colchicine (0.2%) and dimethyl sulfoxide (2%) during 2, 4 and 6 hours. Flow cytometry analysis was performed in 135 surviving plants. Only one induced 4x plant was recovered, which arose from the treatment of 6 hours with colchicine. The result was confirmed by traditional chromosome counts in root-tip cells. Embryological analysis of 120 mature ovaries, conducted by differential interferential contrast (DIC) microcopy showed the typical structure of the meiotic embryo sac revealing that this induced tetraploid individual reproduced sexually. The induced 4x plant failed to set seed following self-pollination, maintaining the self-incompatibility system of the diploids. However, the plant produced seed after crosses with pollen of the wild apomictic tetraploid cytotype. The sexual self-incompatible 4x plant constitutes a novel suitable female parent in crosses with plants of the apomictic tetraploid cytotype or other apomictic tetraploids from related species. The results suggest that it is possible to break apomixis in natural tetraploids opening the possibility for using their genes in a plant improvement program.This work was supported by the Secretaría General de Ciencia y Técnica, Universidad Nacional del Nordeste (UNNE), Argentina (PI 17A012); Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT), Argentina (PICT 2015-0158); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina (PIP 11220150100105CO).