New wild diploids in Paspalum notatum Flügge (Poaceae): potential accessions for use in breeding.

Juliana Maria Fachinetto,Miguel Dall’Agnol,Carine Simioni,Maria Teresa Schifino-Wittmann,Mariana Rockenbach Ávila

doi:10.1590/1984-70332018v18n4n63

Abstract

Abstract Paspalum notatum is a polymorphic species with two accepted varieties, according to the ploidy level. The ploidy level is closely related to the reproductive mode of this species. Usually, diploid cytotypes have sexual reproduction, and tetraploid cytotypes have an apomictic reproduction. Apomixis limits genetic recombination, hindering the development of new cultivars. The identification of sexual plants represents many possibilities in breeding programs. This study aimed to analyze the chromosome number in P. notatum accessions under agronomic evaluation. Ploidy level was determined in 25 accessions. Two ploidy levels were detected, resulting in 21 tetraploid and four diploid accessions. The four diploid accessions originate from Argentina and Uruguay, in a region close to the origin of Pensacola, which is a diploid sexual cultivar of P. notatum. These new diploid accessions may be useful in the development of breeding programs of Paspalum species.

Highlights

Paspalum L. comprises about 350 species distributed in tropical and subtropical American natural pastures (Zuloaga and Morrone 2005)
In the genus Paspalum, polyploidy is associated with apomixis (MoraesFernandes et al 1974, Delgado et al 2014), which is defined as an asexual mode of reproduction by seeds (Martinez et al 2007)
This reproduction mode is an obstacle to the genetic breeding because it hinders genetic recombination and cultivars protection (Huber et al 2016)

Summary

Introduction

Paspalum L. comprises about 350 species distributed in tropical and subtropical American natural pastures (Zuloaga and Morrone 2005). Brazil has no native diploid varieties of this species, only tetraploids (2n=2x=40 chromosomes), which occur in pastures in the Americas, from Central Mexico to Uruguay (Quarin et al 1984). In the genus Paspalum, polyploidy is associated with apomixis (MoraesFernandes et al 1974, Delgado et al 2014), which is defined as an asexual mode of reproduction by seeds (Martinez et al 2007). This reproduction mode is an obstacle to the genetic breeding because it hinders genetic recombination and cultivars protection (Huber et al 2016).

Objectives

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Results